1998 Spring Meeting Special Session Descriptions

UNION Section
ATMOSPHERIC SCIENCES Section
GEODESY Section
GEOMAGNETISM AND PALEOMAGNETISM Section
HYDROLOGY Section
MINERALOGICAL Society
     OCEAN SCIENCES Section
PLANETOLOGY Section
SEISMOLOGY Section
SPACE PHYSICS AND AERONOMY Section
     SPA - AERONOMY Subsection
     SPA - HELIOSPHERIC PHYSICS Subsection
     SPA - MAGNETOSPHERIC PHYSICS Subsection
TECTONOPHYSICS Section
VOLCANOLOGY, GEOCHEMISTRY, AND PETROLOGY Section

U01   Integrated Spatial Information for Earth System Science
THIS SPECIAL SESSION HAS BEEN CANCELED.

Convener: Alan Gaines, NSF, Div. Earth Sciences, Rm. 785, 4201 Wilson Blvd., Arlington, VA 22230, Phone: +1-703-306-1553, Fax: +1-703-306-0382, E-mail: againes@nsf.gov

U02   Catastrophic Glacier Outburst Floods and Environmental Change
Given the recent catastrophic glacier outburst flood in Iceland (November, 1996) triggered by subglacial volcanism and the new emerging datasets and interpretations of such events, this session seeks to bring together scientists from around the world in a forum concerned with the impact of these extremal hydrologic (and geomorphic) events on regional to global environments. The November, 1996 jokulhlaup in Iceland demonstrated a flood discharge rate over five times that of the 1993 Mississippi flood and the landscape altering and environmental consequences are only being understood now. New modeling and remote sensing perspectives now allow scientists to better understand these truly catastrophic events, and the natural hazards associated with jokulhlaups in such places as Washington state, South America is emerging as an important human consideration.

Conveners: Jim Garvin, NASA/GSFC, MC 921, Greenbelt, MD 20771, Phone: +1-301-286-6565, fAX: +1-301-286-1616, E-mail: garvin@denali.gsfc.nasa.gov; Richard S. Williams, Jr., U.S. Geological Survey, Woods Hole Field Center, 384 Woods Hole Road, Woods Hole, MA 02543-1598, Phone: +1-508-457-2347, Fax: +1-508-457-2310, E-mail: rswilliams@usgs.gov; and Dr. Dorothy Hall, NASA Goddard Space Flight Center, Mail Code 974, Greenbelt, MD 20771, Phone: +301-286-6892

U03    The Geodynamo: Numerical Simulations, Laboratory Experiments and Geophysical Observations
Recent advances on many fronts make this an ideal time to integrate progress in understanding the geodynamo. The purpose of this session is to facilitate fruitful integration of results from various numerical simulations employing different simplifying assumptions and boundary conditions, from laboratory experiments and seismological observations of relevant core properties and processes, from space probes of other planetary dynamos, and from historic and paleomagnetic observations of the geomagnetic field.

Conveners: Rob Coe, Earth Sciences Dept., University of California, Santa Cruz, CA 95064, Phone: +1-408-459-2393, Fax: +1-408-459-2127, E-mail: rcoe@rupture.ucsc.edu; and Gary Glatzmaier, Institute of Geophysics and Planetary Physics, Los Alamos National Laboratory, MSC305, Los Alamos, NM 87545, Phone: +1-505-667-7647, Fax: +1-505-665-3107, E-mail: gag@lanl.gov

U04   Geographic Information Systems in Earth Sciences
Geographic Information Systems (GIS) and organized databases are becoming increasingly more important in earth science community for both research and teaching purposes. As we enter into the information age, interdisciplinary research fields are becoming increasingly important. A goal of this session is to bring together researchers from different fields in the earth sciences to discuss their scientific GIS applications. Additionally, this session is intended to act as a forum to discuss future requirements anticipated to handle the exponentially increasing volume of digital data available to the community, distribution methods, interactive manipulation of the data over the Web, and documentation requirements for such data. Special focus will be on discussing current research and scientific results obtained through the use of GIS and organized database systems.

Conveners: Dogan Seber, Department of Geological Science, Cornell University, Snee Hall, Ithaca, NY 14853, Phone: +1-607-255-1159, Fax: +1-607-254-4780, E-mail: seber@geology.cornell.edu; and David Steer, Department of Geological Science, Cornell University, Snee Hall, Ithaca, NY 14853, Phone: +1-607-255-1159, Fax: +1-607-254-4780, E-mail: steer@geology.cornell.edu

U05   Incorporating Human Dimensions in Earth System Models
From the perspective of Global Change, the Earth System can be divided into physical climate, biogeochemical, and human components. While there are strong and growing links between physical climate and biogeochemical research, the links to the human dimension have largely been ignored. The reasons for this are partly because the social, economic, and political sciences comprise a different scholarly community than the physical and biogeochemical sciences, and partly because modeling the complexities of modern human society is an exceedingly difficult task, particularly when future projections are involved. However, anthropogenic activity is a major (and perhaps dominant) driver for global change. In order to develop prognostic biogeochemical models, it is critical to accurately account for changes in the driving forces stemming from human activity. While this is not yet possible, some socio-economic models exist now, and others are currently being developed. Their development in a way which can be coupled to physical climate and biogeochemical models will ultimately enable the modeling community to make reliable estimates of future impact of global change on the basis of evolving drivers to the system. This special session represents an preliminary attempt to bring together researchers from the physical, biogeochemical, and human dimensions arenas to explore the way ahead.

Conveners: Dork Sahagian, IGBP/GAIM, EOS University of New Hampshire, Phone: +1-603-862-3875, Fax: +1-603-862-0188, E-mail: gaim@unh.edu; and Larry Kohler, IHDP, University of Bonn, Nusallee 15a, D-53115 Bonn, Germany, Phone: +49-228-739-050, Fax: +49-228-739-054, E-mail: kohler.ihdp@uni-bonn.de

U06   Special Session in Commemoration of Dr. Jurgen Rahe
Dr. Jurgen Rahe, science program director for exploration of the solar system at NASA Headquarters, died tragically June 18 in the Washington, DC area. Rahe had a distinguished career in NASA and in the fields of astronomy and space science. During his time at NASA Headquarters he served as discipline scientist, chief scientist for planetary astronomy and Director of the Solar System Exploration Division. He was a program scientist for Clementine, Rosetta and NEAR, was a co-investigator on ESA's Giotto mission, and prior to his time at NASA and JPL was Director of the Astronomical Institute of the University Erlangen-Nuremberg in Germany. Jurgen's ability to work with a broad spectrum of the planetary community, his kindness and intelligence, were well known in the United States and around the world. This half-day special session will feature invited papers honoring Jurgen's contributions toward furthering the planetary exploration endeavors of the United States and Europe, as well as his research contributions in astronomy. Jurgen's sincerity, perceptiveness and intellect will be sorely missed.

Conveners: Carl Pilcher, NASA Headquarters, Code SR, Washington, DC 20546, Phone: +1-202 358-0291, Fax: +1-202-358-3097, E-mail: carl.pilcher@hq.nasa.gov; and Jonathan Lunine, University of Arizona, Tucson, AZ, 85721, Phone: +1-602-621-2789, Fax: +1-602-621-4933, E-mail: jlunine@lpl.arizona.edu

U07   Successful Mentoring Relationships: What is Required of Mentor and Mentee
Major changes in career opportunities, research funding, methods of science education, and a sense of scientists' responsibility to society are generating confused expectations about the future of geosciences students. Attempts to attract the broadest spectrum of students to the geosciences are another source of change and confused expectations. Amidst this confusion, students need guidance and assistance. A mentoring relationship can best provide this support, but to be successful its responsibilities must be accepted by both mentor and mentee. Members of an invited panel will, first, give oral presentations of how mentors and mentees may develop a successful relationship, and they, then, will be available for informal concurrent discussions around the session room.

Conveners: Dean A. McManus, School of Oceanography, University of Washington, Box 357940, Seattle, WA 98195-7940, Phone: +1-206-543-0587, Fax: +1-206-543-6073, E-mail: mcmanus@ocean.washington.edu; and Janet Herman, Department of Environmental Sciences, University of Virginia, Charlottesville, VA, 22903, Phone: +1-804-924-7761, Fax: +1-804-982-2137, E-mail: jherman@virginia.edu

U08   Preparing Future Geosciences Faculty
Some geosciences departments have a history of preparing their graduate students for faculty careers, particularly by providing them with opportunities to improve their teaching ability. Other departments have developed such programs more recently. In this session, several of these programs will be described, with emphasis on the expectations of faculty and students, methods used, and assessment of results. Advice for beginning and implementing a program will be included.

Conveners: Dean A. McManus, School of Oceanography, University of Washington, Box 357940, Seattle, WA 98195-7940, Phone: +1-206-543-0587, Fax: +1-206-543-6073, E-mail: mcmanus@ocean.washington.edu; and Heather Macdonald, Department of Geology, College of William and Mary, Williamsburg, VA 23187-8795, Phone: +1-757-221-2443, Fax: +1-757-221-2093, E-mail: rhmacd@facstaff.wm.edu

U09   Geophysics and the Military: Historical Perspectives
This session examines historical interactions between the geophysical community and its military patrons. Scientists seeking support for basic geophysical research have frequently found generous military patrons. On the other hand, the needs of modern warfare have often called for increasingly sophisticated geophysical knowledge. These trends have been magnified, but certainly did not originate, in the twentieth century. Papers from all eras are solicited that provide critical, historical perspectives on the ways military relationships enhance or distort the scientific process.

Conveners: James R. Fleming, Science, Technology, and Society Program, Colby College, Waterville, ME 04901, Phone: +1-207-872-3548, Fax: +1-207-872-3074, E-mail: jrflemin@colby.edu; and Bruce Hevly, Department of History, Box 35356, University of Washington, Seattle, WA 98195, Phone: +1-206-543-9417, Fax: +1-206-543-9451, E-mail: bhevly@u.washington.edu

U10   Technology in the Earth and Space Science Classroom: What Works?
There are many reasons to bring state-of-the-art multimedia software, CD-ROMs, the World Wide Web, video, digital imaging, etc., into the classroom, and many of us have done so. Clearly, just as no one teaching style works for all students, no one technology works best for all students. Still, what are some of our success stories or failures? Do we know why some technology applications have worked while others have failed? We invite contributions of successful (and unsuccessful!) applications of technology in the classroom, especially those tested for some measure of effectiveness. What are some of the challenges of using technology in large introductory classes versus small courses for majors? Are there applications that allow students to work with large data sets? Access will be provided for computers and other multimedia presentations. Please note that AGU policy for this meeting permits a second contributed first-author abstract to a special session with an educational theme such as this one.

Conveners: Randall M. Richardson, Department of Geosciences, University of Arizona, Tucson, AZ 85721-0077, E-mail: rmr@U.Arizona.edu; and Steve Semken, Navajo Dryland Environmental Laboratory, Dine College, Shiprock, Navajo Nation, NM, E-mail: scsemken@shiprock.ncc.cc.nm.us

U11   Earth System Science Education: Shared Learning Resources
Helping students understand the Earth as a system has been the challenge of educators at all levels. In this session we invite papers that share content, methods, and tools that have been developed at all grade levels (K-12 through graduate) to facilitate the learning of Earth System Science and help us understand how students learn about the Earth as a system. Topics include but are not limited to the use of visualizations (satellite pictures or graphical) in Earth System Science education at all grade levels, the development of Earth System Science courses and specialized learning resources and modules, the development of informal programs and exhibits in museums for the public, and the use of technology to facilitate the learning of Earth System Science. Also encouraged are papers that address Earth system learning resources and programs designed for pre-service teachers and education majors.

Conveners: Tamara S. Ledley, TERC, 2067 Massachusetts Ave., Cambridge, MA 02140, Phone: +1-617-547-0430, Fax: +1-617-349-3535, E-Mail: Tamara_Ledley@terc.edu; and Donald R. Johnson, USRA, 1225 W. Dayton, Madison, WI 53706, Phone: +1-608-262-2538, Fax: +1-608-262-5974, E-Mail: donj@ssec.wisc.edu

A01   Pre-Quaternary Paleoclimate Model-Data Discrepancies: Potential for Reconciliation (Joint with OS)
The purposes of the session will be to (1) define outstanding discrepancies between paleoclimate models and conditions inferred from climatically sensitive records, (2) identify most-likely causes of these discrepancies, and (3) discuss potential solutions to the problem. The models can be improved when we know better where they fail to reproduce reliable climate interpretations based on the proxy records, while the quality of the interpretation of climate indicators can be improved when they are viewed in the context of a global, physically consistent system. The session will be an opportunity for those interested in diverse paleoclimate modeling approaches, data sources, and climate change issues to interact.

Conveners: Mark T. Gibbs, Center for Climatic Research, Univ. of Wisconsin-Madison, 1225 W. Dayton St., Madison, WI 53706, Phone: +1-608-265-5279, Fax: +1-608-263-4190, E-mail: gibbs@meteor.wisc.edu; and Karen L. Bice, Earth System Science Center, Pennsylvania State Univ., 248 Deike Building, University Park, PA 16802, Phone: +1-814-863-3673, Fax: +1-814-865-3191, E-mail: kbice@essc.psu.edu

A02   Ozone-Alkene Reactions: Mechanisms, Radical Generation, and Atmospheric Implications
Reactions between ozone and unsaturated hydrocarbons may be a significant source of radicals at urban and regional scales. However, the magnitude of this source and the underlying chemical mechanism behind it remains uncertain. This session will explore both the reliability of laboratory experiments showing evidence for radical production and the significance of these radical sources in the urban and regional atmosphere. Abstracts are encouraged in three areas (1) Laboratory studies exploring the yields of various radicals (OH, HO2, thermal Criegee radicals, etc.) in ozonolysis reactions, (2) Theoretical studies of the radical production mechanism, and (3) Modeling studies focusing on the significance of and uncertainties in the radical production.

Conveners: Neil M. Donahue, Dept. of Chemistry, Harvard University, Cambridge, MA 02138, Phone: +1-617-495-5922, Fax: +1-617-495-4902, E-mail: Neil_Donahue@huarp.harvard.edu; and Geert K. Moortgat, Max Planck Inst. Chemistry, Atmospheric Chemistry Div., P.O. Box 3060, D-55020 Mainz, Germany, Phone: +49-6131-305-476, Fax: +49-6131-305-436, E-mail: moo@diane.mpch-mainz.mpg.de

A03   The Role of Vegetation in Biosphere-Atmosphere Interactions (Joint with H)
The state of vegetation reflects the two-way interactions between the atmosphere and the terrestrial biosphere. In one direction, the large-scale distribution of vegetation plays an important role in regulating the patterns of the fluxes of heat, moisture, momentum, and carbon at the land-atmosphere boundary. In the other direction, the same vegetation distribution is largely determined by the history of climatic conditions describing incoming solar radiation, as well as temperature, and humidity in the atmosphere and the soil. Papers describing theoretical, observational, or modeling studies are solicited concerning the issue of biosphere-atmosphere interactions, including: representation of vegetation in climate models, regional and global feedbacks and responses, impact of land cover change (e.g., deforestation) on climate, representation of vegetation dynamics in climate models, two-way biosphere-atmosphere interactions, and the role of vegetation in paleoclimates.

Conveners: Elfatih Eltahir, Room 48-207, MIT, Cambridge, MA 02139, Phone: +1-617-253-6596, Fax: +1-617-253-7462, E-mail: eltahir@mit.edu; and Jonathan A. Foley, Institute for Environmental Studies, Univ. of Wisconsin, 1225 West Dayton Street, Madison, WI 53706, Phone: +1-608-265-5144, Fax: +1-608-263-4190, E-mail: jfoley@facstaff.wisc.edu

A04   Water Vapor in the Upper Troposphere and the Stratosphere
Water vapor is an important radiative constituent in the upper troposphere and the stratosphere, and it is the main source of hydrogen radicals (and hence of importance for ozone photochemistry). Furthermore, water vapor provides information on transport in this region, including characteristics of mixing and stratosphere-troposphere exchange. We solicit papers on analysis and interpretation of water vapor observations from aircraft, balloon and satellite data. This includes observations of the seasonal and interannual variability in global data (such as long-term trends or the observed effects of the 1997-98 El Ni±o), and studies of mechanisms which maintain the observed distributions. We also welcome model studies of the radiative and chemical effects of water vapor variations, in particular those related to the recent observed trends.

Conveners: William J. Randel, National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, Phone: +1-303-497-1439, Fax: +1-303-497-1492, E-mail: randel@ucar.edu; Samuel J. Oltmans, NOAA, Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80303, Phone: +1-303-497-6676, Fax: +1-303-497-6290, E-mail: soltmans@cmdl.noaa.gov; and Eric Hintsa, Department of Chemistry, Harvard University, 12 Oxford St., Cambridge, MA 02138, Phone: +1-617-495-5922, Fax: +1-617-495-4902, E-mail: hintsa@bottesini.harvard.edu

A05   Biogeochemical Cycles and Air-sea Exchange
The fluxes of trace species between the atmosphere and the ocean exert a strong influence on the biogeochemical cycles of various substances important to climate. Atmospheric deposition of trace metals, nutrients and other trace species modulates oceanic productivity and affects the carbon and sulfur cycles. The ocean emits several trace species important for marine atmospheric chemistry with implications for the global oxidative and radiative balance. We solicit contributions on experimental, observational and theoretical studies of air-sea exchange, with a focus on how these fluxes may have responded to changes in biogeochemical cycles over the last several decades. Papers addressing the couplings between global-scale systems are particularly desired.

Conveners: David J. Erickson, III, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, Phone: +1-303-497-1424, Fax: +1-303-497-1400, E-mail: erickson@acd.ucar.edu; and Richard Arimoto, Carlsbad Environmental Monitoring and Research Center, New Mexico State University, 1400 University Drive, Carlsbad, NM 88220, Phone: +1-505-234-5503, E-mail: arimoto@cemrc.nmsu.edu

A06   Beginning the Future in Atmospheric Sciences
The goals of this session are to highlight research efforts of students in the atmospheric sciences and to provide students with an overview of career options available upon graduation. All contributed talks will be short research presentations by students (undergraduate or graduate) involved in any area of atmospheric science. Invited talks will focus on identifying and defining career options available for students with a strong research background in atmospheric science. These talks will be given by key members of the research community whose careers span academics, government laboratories, contract research, and granting agencies.

Conveners: Jane Van Doren, Dept. of Chemistry, College of the Holy Cross, 1 College St., Worcester, MA 01610-2395, Phone: +1-508-793-3376, Fax: +1-508-793-3530, E-mail: jvandoren@holycross.edu; and Douglas R. Worsnop, Aerodyne Research, 45 Manning Road, Billerica MA 01821-3976, Phone: +1-508-663-9500, Fax: +1-508-663-4918, E-mail: Worsnop@aerodyne.com

A07   Hydrological and Biogeochemical Controls on Atmosphere-Biosphere Exchange with Boreal Soils (Joint with H)
The cycling of biogeochemical species and their subsequent exchange between soils and the atmosphere is controlled by a complex set of interactions involving soil hydrology, biogeochemistry, climate and ecology. Many field and modeling studies are now looking at explaining such exchanges from a fundamental understanding of the underlying production, consumption and transport of gaseous or dissolved forms of globally significant compounds. For this session we are calling for papers that illustrate via observational and/or modeling studies the interactions among processes controlling the biogeochemistry of soils of forested and wetland boreal ecosystems.

Conveners: Patrick Crill, Complex Systems Research Center, Inst. for the Study of Earth, Oceans and Space, Univ. of New Hampshire, Durham, NH 03824, Phone: +1-603-862-3519, Fax: +1-603-862-0188, E-mail: patrick.crill@unh.edu; and Nigel Roulet, Dept. of Geography and Centre for Climate and Global Change Research, McGill Univ., 805 Sherbrooke St. West, Montreal, QC H3A 2K6, Canada, Phone: +1-514-398-4945, Fax: +1-514-398-1381, E-mail: roulet@felix.geog.mcgill.ca

A08   Hydrometeorological Data Assimilation (Joint with H)
Data assimilation is the application of the set of mathematical techniques that provide physically consistent estimates of spatially distributed environmental variables. The estimates are based on merging scattered and/or indirect observations (e.g. remote sensing) of states and parameters with dynamic models that impose physical consistency constraints. This special session is focused on the emerging applications of advanced data assimilation techniques to hydrometeorological and hydrological estimation problems. Both methodological papers on the mathematical formulation and solution procedure and application papers are included. The special session begins with introductory tutorials, followed by technical contributions, and ending with extensive participant discussion.

Conveners: Dennis McLaughlin, MIT, 48-209, Cambridge, MA 02139, Phone: +1-617-253-7176, Fax: +1-617-258-8850, E-mail: dennism@mit.edu; and Dara Entekhabi, MIT, 48-331, Cambridge, MA 02139, Phone: +1-617-253-9698, Fax: +1-617-258-8850, E-mail: darae@mit.edu

A09   Atmospheric Studies in the Mexico City Basin
In the past six years a number of research programs have been conducted in the Mexico City Basin to study its regional meteorology, photochemistry, and particle formation mechanisms. This session will focus on ascertaining the present state of our understanding of how local meteorology impacts the transport of gases and particles in and out of Mexico City; the spatial and temporal evolution of photochemical species; and the origin and evolution of aerosols in this region. Abstracts are encouraged that address these or related issues.

Conveners: Graciela Raga, Centro de Ciencias de la Atmosfera, UNAM, Ciudad Universitaria, 04510 Mexico DF, Mexico, phone: +525-622-4085, Fax: +525-616-0789, E-mail: raga@servidor.dgsca.unam.mx; Greg Kok, Research Aviation Facility, National Center for Atmospheric Research, Boulder, CO 80307, Phone: +1-303-497-1070, Fax: +1-303-497-1092, E-mail: greg@raf.atd.ucar.edu

A10   Diagnosing Atmospheric Transport: The Age of Air
The transport of atmospheric constituents between two points is best described by a distribution of transit times, the "age spectrum." Although the age spectrum itself is not directly observable, characteristics of it have been inferred from tracer measurements. For example, the stratospheric lags of SF₆ and CO₂ from their tropospheric trends are good estimates of the "mean age" (the mean of the age spectrum) of stratospheric air with respect to the surface sources. In this session, we invite observational and modeling studies of global transport timescales, both in the troposphere and stratosphere.

Conveners: Timothy Hall, NASA Goddard Inst. for Space Studies, 2880 Broadway, New York, NY 10025, Phone: +1-212-678-5592, Fax: +1-212-678-5552, E-mail: thall@giss.nasa.gov; and Kristie Boering, Dept. Earth and Planetary Sciences, Harvard University, 20 Oxford St., Cambridge MA 02138, Phone: +1-617-495-5361, Fax: +1-617-495-2768, E-mail: kab@io.harvard.edu

A11   Seasonal and Interannual Variability, and Trends, in Stratospheric Trace Gases and Aerosol From UARS and Other Space-Based Platforms
The Upper Atmosphere Research Satellite (UARS) 6+ year data base on stratospheric ozone and aerosols augments data provided by TOMS, SAGE, and SBUV. In addition, UARS data indicate trends in H₂O, CH₄, HF, ClO, and other critical trace species, and they contain unique information on the effects of a massive volcanic eruption on lower stratospheric chemistry and radiative balance. Papers are solicited on seasonal and interannual variability and trends in ozone, stratospheric trace gases, and aerosols, as revealed by the UARS and other global data bases. Papers on stratospheric trace gas/aerosol climatologies based on the satellite observations also are welcome.

Conveners: Aidan E. Roche, Lockheed Martin Palo Alto Research Lab., Dept.H1-11, B255, 3251 Hanover St., Palo Alto, CA 94304, Phone: +1-650-424-2109, Fax: +1-650-424-3333, E-mail: roche@claes.space.lockheed.com; and Richard S. Stolarski, Code 916, NASA Goddard Space Flight Center, Greenbelt Rd., Greenbelt, MD 20771, Phone: +1-301-286-9111, Fax: +1-301-286-1754, E-mail: stolar@polska.gsfc.nasa.gov

A12   Atmospheric Effects of Aviation
Recent assessments indicate that the current and future aircraft fleet, including possible high-speed civil transport aircraft, may significantly affect the atmosphere, but the uncertainties in the impacts are large. Studies of the atmospheric effects of aviation have produced a better understanding of the chemistry, particle microphysics, and dynamics of the atmosphere along with knowledge of the processes by which aircraft emissions interact with the background atmosphere. We solicit papers pertaining specifically to the atmospheric effects of aviation at cruise altitudes, including observations and model studies, as well as laboratory studies and emission characterization. Effects of subsonic aircraft on tropospheric chemistry will be emphasized, but contributions on all aspects are welcome.

Conveners: S. Randolph Kawa, NASA Goddard Space Flight Center, Code 916, Building 21, Room 245A, Greenbelt, MD 20771, Phone: +1-301-286-5656, Fax: +1-301-286-1662, E-mail: kawa@maia.gsfc.nasa.gov; and Donald E. Anderson, The Johns Hopkins University, Applied Physics Lab, Johns Hopkins Rd, Laurel, MD 20723, Phone: +1-301-953-6174, Fax: +1-301-953-6670, E-mail: don.anderson@jhuapl.edu

A13   Modeling Stratospheric Ozone
This session will explore the strengths and weaknesses of models which calculate the concentration of stratospheric ozone. Papers should focus on observations as the key to model evaluation. We request papers which a) calculate ozone change on seasonal, interannual or decadal time scales, b) calculate ozone change on global or limited spatial scales (e.g., midlatitude, polar), or c) explore the importance of model resolution and representation of subscale processes to modeled ozone change. The session will provide an opportunity to define outstanding issues in ozone modeling.

Conveners: Anne R. Douglass, Code 916 NASA Goddard Space Flight Center, Greenbelt, MD 20771, Phone: +1-301-286-2337, Fax: +1-301-286-1754, E-mail: douglass@persephone.gsfc.nasa.gov; and Richard S. Stolarski, Code 916, NASA Goddard Space Flight Center, Greenbelt, MD 20771, Phone: +1-301-286-9111, Fax: +1-301-286-1754, E-mail: stolar@polska.gsfc.nasa.gov

A14   Trends in the Ozone as a Function of Altitude
This session will consider the evidence for ozone change over the last few decades as a function of altitude. Several invited presentations will highlight results of the recent Stratospheric Processes And their Relation to Climate (SPARC) ozone trends review. Analyses including data from satellites (SAGE and SBUV), Umkehr and ozonesondes will be presented. We solicit further papers which examine various aspects of trend analysis of ozone data including variability associated with the QBO, solar cycle, aerosols, ENSO and changes in dynamics/transport and also the agreement between the deduced profile trends and column ozone changes.

Conveners: Richard S. Stolarski, Code 916, NASA Goddard Space Flight Center, Greenbelt, MD 20771, Phone: +1-301-286-9111, Fax: +1-301-286-1754, E-mail: stolar@polska.gsfc.nasa.gov; and William Randel, Atmospheric Chemistry Division, NCAR Boulder, CO 80307, Phone: +1-303-497-1439, Fax: +1-303-497-1492, E-mail: randel@acd.ucar.edu

A15   Summer 1997 Ozone Photochemistry Experiment
Continuous measurements of CO, O₃, PANs, UV, and meteorological parameters began in 1997 through the Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET). Measurements of RO_x, peroxides, carbonyl compounds (e.g., isoprene and its oxidation products), isoprene fluxes, other NMHCs, NO, NO₂, NO_y, and aerosol number and vertical profiles were added during one or both short summer intensives. The session will focus on the photochemical and transport processes contributing to the production of ozone in air reaching the site during the summer of 1997, a preliminary climatology, and implications for the export of ozone and/or its precursors to the northeastern United States and Canada.

Conveners: Mary Anne Carroll, Dept. of Atmospheric, Oceanic, and Space Sciences, Univ. of Michigan, 2455 Hayward St., Rm. 1518 SRB, Ann Arbor, MI 48109-2143, Phone: +1-313-763-4066, Fax: +1-313-764-5137, E-mail: mcarroll@umich.edu; and Paul B. Shepson, Purdue Univ., Depts. of Chemistry, and Earth and Atmospheric Sciences, 1393 Brown Building, West Lafayette, IN 47907-1393, Phone: +1-765-494-7441, Fax: +1-765-494-0239, E-mail: pshepson@cv3.chem.purdue.edu

A16   Early Results from the CRISTA (CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere) Experiment
The CRISTA instrument flew on board the space shuttle in November 1994 and again in August 1997. Global temperature and trace gas measurements of unprecedented horizontal resolution (300 km) were made using a three-telescope observing system. Gases measured include passive tracers such as methane, CFC11 and N₂O as well as chemically active species such as ozone and HNO₃. This session will present analyses of middle atmospheric dynamical and chemical processes using these important new data.

Conveners: Julio T. Bacmeister, Code 7641, Naval Research Lab, Washington, DC 20375, Phone: +1-202-767-2821, Fax: +1-202-404-8090, E-mail: julio@ismap5.nrl.navy.mil; and Dirk Offermann, Physics Dept., Wuppertal Univ., Gauss-str. 20, 42119 Wuppertal, Germany, Phone: +49-202-439-2604, Fax: +49-202-439-2680, E-mail: offerm@wpos2.physik.uni-wuppertal.de

G01   The Impact of El Niño and Other Low-Frequency Signals on Earth Rotation and Global Earth System Parameters (Joint with A, OS)
The El Niño signal that began in early 1997 promises to be a major global phenomenon with impacts on many aspects of the climate and Earth dynamic systems. Responses to earlier El Niño/Southern Oscillation signals have included fluctuations in global and regional atmospheric angular momentum, in ocean temperature and mass signals, and in Earth rotation rate, reckoned as length-of-day series. Polar motion can also be affected by the strong El Niño signals, and mass redistributions in oceans and atmosphere may noticeably impact the gravitational field as well. Other variations in these geodetic parameters are occurring on interannual time scales, and understanding seasonal signatures related to motions of the geophysical fluids is important too. Here we seek contributions of both long- and short-term studies of Earth rotation and related parameters, including the influence of the recent El Niño event. Precise TOPEX/Poseidon and other altimetric measurements of mean sea level variations during this El Niño event will be very useful in all these studies.

Conveners: David A. Salstein, Atmospheric and Environmental Research,Inc., 840 Memorial Drive, Cambridge, MA 02139, Phone: +1-617-547-6207, Fax: +1-617-661-6479, E-mail: salstein@aer.com; and Barbara Kolaczek, Space Research Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland, Phone: +48-22-403766, Fax: +48-22-403131, E-mail: kolaczek@cbk.waw.pl

G02   Geoid Determination Over Global and Regional Scales
Global and regional high resolution and high accuracy geoid determination has been a central topic of geodetic research for several years. Its importance is well appreciated by the geodetic, oceanographic and geophysical communities. This topic is receiving continuing and renewed interest as a result of its implications on rapid orthometric height determination (based on GPS positioning), dynamic ocean topography determination (based on spaceborne altimetry) and future Satellite Laser Altimeter missions, aiming to map the Earth's topography (such as VCL and GLAS). New satellite systems are being developed and proposed (CHAMP, GRACE, GOCE) to improve the global geoid model. Other, more indirect approaches are also being considered, such as oceanic geoid improvement using Ocean Circulation Model information, altimeter data and global geopotential model information in a simultaneous adjustment. Common to all geoid determination approaches is the need for reliable error estimation. We solicit presentations discussing current and future (global or regional) geoid modeling capabilities and their apparent limitations, with emphasis on the accuracy assessment and verification of the resulting models (e.g., using independent data).

Conveners: Nikolaos K. Pavlis, Hughes STX Corporation, 7701 Greenbelt Road, Suite 400, Greenbelt, MD 20770, Phone: +1-301-441-4121, Fax: +1-301-441-2432, E-mail: npavlis@geodesy2.gsfc.nasa.gov; and Christopher Jekeli, Dept. of Civil and Environmental Engineering and Geodetic Science, The Ohio State University, 2070 Neil Avenue, Columbus, OH 43210, Phone: +1-614-292-7117, Fax: +1-614-292-2957, E-mail: jekeli.1@osu.edu

GP01   Long-Core Cryogenic Magnetometers
Automated, high-resolution, long-core cryogenic magnetometers are about to revolutionize the way that paleomagnetists study the paleomagnetic, mineral magnetic and environmental magnetic properties of sedimentary cores. With throughputs that are twenty to fifty times faster than conventional magnetometers, these instruments make it reasonable to consider making magnetic measurements at a 1-cm interval on cores that are tens of meters or even a few hundred meters long. The purpose of this session will be to highlight the different types of studies that have already been undertaken using these instruments and to point the way to new types of studies that have not yet been done. Papers that deal with advances in technology associated with these magnetometers or with the acquisition, processing and analysis of the massive datasets generated by these instruments are also welcome.

Conveners: Kenneth L. Verosub, Dept. of Geology, University of California, Davis, CA 95616, Phone: +1-916-752-6911, Fax: +1-916-752-0951, E-mail: verosub@geology.ucdavis.edu; and Andrew P. Roberts, Department of Oceanography, University of Southampton, Southampton SO14 3ZN, United Kingdom, Phone: +44-1703-593786, Fax: +44-1703-593059, E-mail: Andrew.P.Roberts@soc.soton.ac.uk

GP02   The Geodynamo: Numerical Simulations, Laboratory Experiments and Geophysical Observations (Joint with P, T)
Recent advances on many fronts make this an ideal time to integrate progress in understanding the geodynamo. The purpose of this session is to facilitate fruitful integration of results from various numerical simulations employing different simplifying assumptions and boundary conditions, from laboratory experiments and seismological observations of relevant core properties and processes, from space probes of other planetary dynamos, and from historic and paleomagnetic observations of the geomagnetic field.

Conveners: Rob Coe, Earth Sciences Dept., University of California, Santa Cruz, CA 95064, Phone: +1-408-459-2393, Fax: +1-408-459-2127, Email: rcoe@rupture.ucsc.edu; and Gary Glatzmaier, Institute of Geophysics and Planetary Physics, Los Alamos Natl Laboratory, MSC305, Los Alamos, NM 87545, Phone: +1-505-667-7647, Fax: +1-505-665-3107, Email: gag@lanl.gov

GP03   Paleomagnetism and Paleoclimate
Magnetic properties of soils, sediments and dusts provide powerful tools for resolving key environmental problems. Therefore we invite papers which link rock magnetic signatures with aspects of environmental change such as palaeoclimatic or sediment source variability throughout geological time, soil formation processes or anthropogenic pollution. Studies of interdisciplinary quantification, calibration and/or modelling of the magnetic proxy records based on orbital, geochemical, pedological, botanical or fauna changes etc. will be especially appreciated.

Conveners: Friedrich Heller, Institut fur Geophysik, ETH-Honggerberg CH-8093 Zurich, Switzerland, Phone: +41-1-633-2625 or +41-1-261-1864, Fax: +41-1-633-1065, Email: frieder@mag.geo.phys.ethz.ch; Jim Channell, Department of Geology, University of Florida, 1112 Turlington Hall, Gainesville, FL 32611, Phone: +1-352-392-2231, Fax: +1-352-392-9294, Email: jetc@nervm.nerdc.ufl.edu; and Andrew P. Roberts, Department of Oceanography, University of Southampton, Southampton Oceanography Centre European Way, Southampton SO14 3ZN, U.K., Phone: +44-1703-593786, Fax: +44-1703-593059, Email: Andrew.P.Roberts@soc.soton.ac.uk

GP04   Tectonics and Magmatism of the Arctic Region: Cretaceous to Present (Joint with T)
The Arctic region remains one of the least understood regions in terms of its tectonic and magmatic development. Papers are solicited which present new data and models on the all aspects of Arctic geologic evolution, the nature of large scale magmatism and the relationship between Arctic tectonism and climate.

Conveners: John Tarduno, Department of Geological Sciences, Hutchison Hall, University of Rochester, Rochester, NY 14267, Phone: +1-716-275-2410, Fax: +1-716-244-5869, E-mail: john@skyline.earth.rochester.edu; and Bernard Coakley, Lamont Doherty Earth Observatory, 107 Oceanography, Palisades, NY 10964, Phone: +1-914-365-8156; E-mail: bjc@lamont.ldeo.columbia.edu

GP05   Microbial Biomineralization of Magnetic Iron Minerals
The suggestion that magnetite and other magnetic minerals in a Martian meteorite are of bacterial origin highlights the need for reliable criteria to distinguish biogenic from non-biogenic minerals and a better understanding of the occurrence of bacterially-related magnetic minerals in terrestrial environments. Papers are solicited which discuss all aspects of microbial biomineralization of magnetic iron minerals, including its occurrence in terrestrial environments, new recognition techniques, newly discovered phases and crystal morphologies, its recognition and preservation in ancient environments, and magnetic properties including the ability to record natural remanent magnetization.

Conveners: Bruce M. Moskowitz , Dept. of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, Phone: +1-612-624-1547, Fax: +1-612-625-7502, E-mail: bmosk@maroon.tc.umn.edu; and Richard B. Frankel, Physics Dept., California Polytechnic State University, San Luis Obispo, CA 93407, Phone: +1-805-756-1666, Fax: +1-805-765-1670; E-mail: rfrankel@oboe.aix.calpoly.edu

GP06   The Role of Precession, Solid Earth Tides, and Solid Core Motions in Core Dynamics and the Geodynamo
Although considerable success has been achieved in explaining the geodynamo based on thermal and compositional convections, questions remain. These models assume, for example, that the solid core increases in size at a rate marginally adequate for maintaining the magnetic field over paleo- magnetic time scales. Other models based on observable energy abundant earth-sun-moon dynamics have been proposed, criticized, and re-investigated. This session will explore these alternative mechanisms, their ability to induce core flows needed for known geodynamo models, and their energy adequacy for maintaining the magnetic field, global heat loss, mantle convection, and other Earth phenomena.

Conveners: James Vanyo, Department of Mechanical Engineering/Department of Geological Sciences, University of California, Santa Barbara, Santa Barbara, CA 93106, Phone: +1-805-687-7838, Faz: +1-805-893-8651, E-mail: vanyo@engineering.ucsb.edu; and Richard Kerswell, School of Mathematics, University Walk, Bristol University, BS8 1TW, U.K., Phone: +44-(0)117-928-9126, Fax: +44-(0)117-928-7999; E-mail: R.R.Kerswell@Bris.ac.uk

GP07   Symposium on Contributions from Ocean Drilling to Geomagnetism and Paleomagnetism
This symposium will showcase paleomagnetic results based on samples obtained by ocean drilling. We are soliciting contributions pertaining to the full range of paleomagnetic endeavors from the rock magnetism of the oceanic crust to high-resolution paleosecular variation.

Conveners: Lisa Tauxe, Scripps Institution of Oceanography, La Jolla, CA 92093-0220, Phone: +1-619-534-6084, Fax: +1-619-534-0784, http://sorcerer.ucsd.edu; and B.M. Clement, Florida International University, Dept. Geology, Miami, FL 33199, Phone: +1-305-348-3085, Fax: +1-305-348-3877, E-mail: clementb@servms.fiu.edu

GP08   Paleomagnetism and Tectonics of Active Margins
THIS SPECIAL SESSION HAS BEEN CANCELED FOR THE 1998 SPRING MEETING. IT WILL BE POSTPONED UNTIL THE 1998 FALL MEETING.

Convener:

GP09   Magnetic Anomalies, Rock Magnetism, and Magnetic Mineralogy: Influences, Relationships and Case Studies
The wealth of information which can be gained from high resolution aeromagnetic surveys is often limited by the available information on fundamental rock-magnetic properties and an understanding of geologic processes that determine magnetic signatures. In many instances ancient remanences, unusual oxide compositions, magneto-bacteria, or minor concentration variations can produce subtle but important anomalies. Case studies of high resolution aeromagnetic anomalies and aeromagnetic surveys and their relationships to magnetic petrology are encouraged. In addition, new compilations of aeromagnetic data sets and applications of aeromag surveys to exploration, sedimentary basin studies and depositional environments are welcome.

Conveners: Suzanne A. McEnroe, Geological Survey of Norway, PO Box 3006 - Lade, N-7040 Trondheim, Norway, Phone: (+47) 73 90 44 05, E-mail: Suzanne.McEnroe@ngu.no; and Laurie L. Brown, Department of Geosciences, University of Massachusetts, Amherst, MA 01003, Phone: +1-413-545-0245, E-mail: lbrown@geo.umass.edu

H01   Merging K-12 Environmental Education and Volunteer Monitoring (Joint with A, OS)
Currently, there are limited data on key environmental factors (e.g., water quality, rainfall, biometry, soil types) in most parts of the world. Obtaining baseline measurements is key to evaluating changes in environmental conditions due to local perturbations (such as industrialization or mining) and global changes. There have been a number of recent programs to incorporate environmental measurements into K-12 educational programs, as well as the development of volunteer monitoring networks. With data collected by schools and volunteers there are often questions about data quality, spatial and temporal coverages and availability of both data and supporting metadata. The purpose of this session is threefold: (1) To present case studies that have used student and volunteer data; (2) To demonstrate the development of data bases and quality control procedures; and (3) To highlight the wide variety of volunteer and educational monitoring programs that exist. We encourage abstracts addressing these issues from all disciplines. This is a poster-only session; there will be a discussion section with an invited panel.

Conveners: Martha H. Conklin, Department of Hydrology and Water Resources, P.O. Box 210011, The University of Arizona, Tucson, AZ 85721, Phone: +1-520-621-5829, E-mail: martha@hwr.arizona.edu; and Susan Postawko, Department of Meteorology, University of Oklahoma, 100 E. Boyd Street, Suite 1310, Norman, OK 73019, Phone: +1-405-325-6561, E-mail: spostawk@rossby.metr.ou.edu

H02   Soil Mechanics and Geotechnical Controls of Channel and Hillslope Processes
The dynamics of various landform elements such as stream banks, mass movements, cohesive deposits, and rills are controlled by principles related to soil mechanics and geotechnics. Gravitational forces acting on in situ material interact with surface and sub-surface hydraulic forces to shape channels and hillslopes. Forces such as shear strength, shear stress, pore-pressure, and tension in saturated and unsaturated media exert an important influence on rates and types of erosion processes. The session focuses on recent insights into the role of soil mechanics and geotechnics on channel and hillslope processes and forms.

Conveners: Andrew Simon, USDA-ARS, National Sedimentation Laboratory, 598 McElroy Drive, Oxford, MS 38655; Phone: +1-601-232-2918, Fax: +1-601-232-2915, E-mail: simon@sedlab.olemiss.edu; and Robert Lohnes, Department of Civil and Construction Engineering, Iowa State University, 488 Town Engineering, Ames, IA, 50011-3232; Phone: +1-515-294-7846, E-mail: rlohnes@iastate.edu

H03   The Southern Great Plains 1997 (SGP97) Hydrology Experiment
The SGP97 Experiment took place June 18-July 17, 1997 in a 40 x 250 km region extending from southwestern to north-central Oklahoma. The main objectives of the experiment were: 1. to establish that the retrieval algorithms for surface soil moisture developed at higher spatial resolution using truck- and aircraft-based sensors can be extended to the coarser resolutions expected from satellite platforms; 2. to verify spatial-temporal estimators of soil moisture and to examine the utility of pedotransfer function in hydrologic modeling; 3. to examine the feasibility of inferring soil moisture and temperature profiles using surface observations in conjunction with in situ measurements, and 4. to examine the effect of soil moisture on the evolution of the atmospheric boundary layer and clouds over the Southern Great Plains during the warm season. SGP97 combined field measurements with a host of aircraft and satellite observations covering a range of temporal and spatial scales. This session is intended to serve as a forum for presenting early results based on analyses of the data collected before and during the experiment. We invite oral and poster contributions from investigators addressing one or more of the above objectives.

Conveners: Christa D. Peters-Lidard, School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive, Atlanta, GA 30332-0355, Phone: +1-404-894-5190, Fax: +1-404-894-2677, E-mail: cpeters@ce.gatech.edu; and Thomas J. Jackson, USDA/ARS Hydrology Laboratory, 104 Bldg 007-BARC West, Beltsville, MD 20705, Phone: +1-301-504-8511, Fax: +1-301-504-8931, E-mail: tjackson@hydrolab.arsusda.gov

H04   Remotely Sensed Observations of the Surface Energy and Carbon Balance
One of the major objectives in recent large scale interdisciplinary field experiments has been an attempt to use remotely sensed data for estimating components of the surface energy and carbon balance. For this session we are calling for papers on the results of these activities. The field experiments include: HAPEX-MOBILHY, FIFE 87 and 89, Monsoon 90, EFEDA, Washita 92 and 94, HAPEX-Sahel and BOREAS. Contributions are encouraged which describe the successes and failures on the use of remotely sensed data for quantifying energy and carbon fluxes using data from these experiments and any other studies where the utility of remote sensing for this purpose is being evaluated.

Conveners: Thomas Schmugge, USDA/ARS Hydrology Lab, Bldg 007 - BARC West, Beltsville, MD 20705-2350, Phone: +1-301-504-8554, Fax: +1-301-504-8931, E-mail: schmugge@hydrolab.arsusda.gov; and William Kustas, USDA/ARS Hydrology Lab, Bldg 007 - BARC West, Beltsville, MD 20705-2350, Phone: +1-301-504-8498, Fax: +1-301-504-8931, E-mail: bkustas@hydrolab.arsusda.gov

H05   Water and Watersheds
Many problems of water quantity and quality are most effectively considered at the watershed scale. These problems are inherently multidisciplinary and the watershed is a landscape unit that naturally integrates terrestrial, aquatic, geologic, and atmospheric processes. The need for research at this scale was recognized by a major NSF/EPA research initiative on water and watersheds. This session provides, in part, a forum for work supported by the NSF/EPA initiative, although the session is open to all and watershed-scale research in hydrology, geomorphology, water chemistry, and biology is welcome, particularly as it contributes to our understanding of the natural and anthropogenic processes that govern the quantity, quality, and availability of water. Student and poster submissions are encouraged.

Conveners: Peter Wilcock, Department of Geography and Environmental Engineering, Johns Hopkins University, Baltimore, MD 21218, Phone: +1-410-516-5421, Fax: +1-410-516-8996, E-mail: wilcock@jhu.edu; M. Robbins Church, U.S. EPA, National Health and Environmental Effects Research Lab, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, Phone: +1-541-754-4424, Fax: +1-541-754-4716, E-mail: church@mail.cor.epa.gov; and Leal Mertes, Department of Geography, University of California, Santa Barbara, CA, 93106, Phone: +1-805-893-7017, Fax: +1-805-893-7782, E-mail: leal@geog.ucsb.edu

H06   Bedform Processes and Patterns (Joint with OS)
Bedforms from fluvial, nearshore and eolian environments display striking similarities in both process and pattern. For example, megaripples formed in wave-dominated nearshore marine environments appear analogous to dunes generated by unidirectional flows in rivers and similar to smaller desert dunes generated by wind. This special session will bring together sediment-transport researchers from different environments to develop an improved perspective on all aspects of bedform mechanics, migration and evolution of bedform patterns. Papers are sought on any aspect of the role of near-bed flow and sediment transport in the development and evolution of bedforms and bedform patterns. Papers may describe field or laboratory observations, including newly developed observational techniques, as well as theoretical and computational approaches to bedform mechanics and patterns.

Conveners: Tom Drake, Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, 1125 Jordan Hall, Raleigh, NC 27695-8208, Phone: +1-919-515-7838, Fax: +1-919-515-7802, E-mail: drake@ncsu.edu; Edith L. Gallagher, Oceanography Dept., Code OC, Naval Postgraduate School, 833 Dyer Road, Rm. 328, Monterey, CA 93943-5122, Phone: +1-408-656-2379, Fax: +1-408-656-2712, E-mail: egallagh@oc.nps.navy.mil

H07   Management of Groundwater Resources in Rural Settings in Developing Countries
Management of groundwater resources in rural settings in developing countries is subject to a number of technical, managerial, and social challenges. This session focuses on recent experience in addressing these challenges. Papers are encouraged which assess potential technical and/or managerial solutions to problems associated with development, maintenance, and protection of groundwater supplies in rural settings in developing countries. Among the topics of interest are design of appropriate technologies (e.g., hand pumps and spring boxes), determination of the benefit of water supplies to the community, and development of management strategies which provide for long term maintenance of water systems and protection of groundwater resources.

Conveners: Stephen E. Silliman, Dept. of Civil Engineering, University of Notre Dame, Notre Dame, IN 46556, Phone: +1-219-631-5846, Fax: +1-219-631-9236, E-mail: silliman@thiem.ce.nd.edu; and Dale Easley, Dept. of Geology and Geophysics, University of New Orleans, New Orleans, LA 70148, Phone: +1-504-280-6316, Fax: +1-504-280-7396, E-mail: Dale_Easley@Compuserve.com

H08   Twenty Years of Stochastic Subsurface Hydrology
This session is expected to facilitate a retrospection on the development of stochastic subsurface hydrology over the last twenty years - the major accomplishments, the challenges that lie ahead, and perceptions of the important achievements; from among researchers, regulatory, complying agencies and applied consultants. Presentations are expected to be of a broad philosophical nature rather than focus on specific details. Presentations could focus on a class of theoretical developments, large-scale computational studies, field methods for characterizing heterogeneity, or the value of important results from the perspective of an applied end-user. Viewpoints from practicing hydrogeologists and consultants are especially encouraged.

Conveners: Hari Rajaram, Department of Civil, Environmental, and Architectural Eng., University of Colorado, Boulder, CO 80309-0428, Phone: +1-303-492-6604, Fax: +1-303-492-7317, E-mail: hari@spot.colorado.edu; and Andrew F. B. Tompson, Lawrence Livermore National Laboratory, Earth Science Division, L-206, PO Box 808, Livermore, CA 94551, Phone: +1-510-422-6348, Fax: +1-510-422-3118, E-mail: afbt@llnl.gov

H09   Natural Restoration of Contaminated Aquifers
Physical, chemical, and biological processes can act to attenuate the concentrations of organic and inorganic contaminants in ground water and naturally restore contaminated aquifers. However, these processes may also cause deleterious effects, such as local increases in concentrations of some contaminants. Great interest exists in evaluating natural attenuation as an alternative to engineered containment and remediation systems, which are expensive and not always effective. Attenuation of hydrocarbons has received the most attention in the scientific and policy communities; this special session will explore natural processes which attenuate the concentration of other contaminants which threaten our ground-water resources as well, such as nutrients, metals, agricultural chemicals, and chlorinated compounds.

Conveners: Kathryn M. Hess, U.S. Geological Survey, 28 Lord Road, Suite 280, Marlborough, MA 01752, Phone: +1-508-490-5029, Fax: +1-508-490-5068, E-mail: kmhess@usgs.gov; Douglas B. Kent, U.S. Geological Survey, 345 Middlefield Road, MS 465, Menlo Park, CA 94025, Phone: +1-650-329-4461, Fax: +1-650-329-4463, E-mail: dbkent@usgs.gov; and Richard L. Smith, U.S. Geological Survey, 3215 Marine Street, Boulder, CO 80303, Phone: +1-303-541-3032, Fax: +1-303-447-2505, E-mail: rlsmith@usgs.gov

H10   Contaminant Transport Across the Ground-Water/Surface-Water Interface
Interest in groundwater and solute discharge is related to the growing awareness of ecological impacts from contaminant movement across the ground-water/surface-water interface, the need to target specific discharge zones accurately enough to develop effective remediation strategies, and the potentially large attenuation capacity of sediment near the interface. Suggested topics include, but are not limited to: (1) biogeochemical transformation of solutes as they move across the groundwater/surface-water interface; (2) ecological impacts of groundwater-related contaminant or nutrient transport (e.g., biotic response, bioconcentration, nutrient cycling); (3) mitigation near discharge areas; (4) methods for locating, tracing and measuring discharge; or (5) physics of flow near the interface.

Conveners: David R. Lee, AECL, Chalk River, ON K0J 1J0, Canada, Phone: +1-613-584-3371, ext. 4710, Fax: +1-613-584-1221, E-mail: leed@crl.aecl.ca; and Don A. Vroblesky, USGS, 720 Gracern Rd., Suite 129, Stephenson Center, Columbia, SC 29210-7651, Phone: +1-803-750-6115, Fax: +1-803-750-6181, E-mail: vroblesk@usgs.gov

H11   Sorption of Organic Pollutants to Soil, Sediment, and Other Geologic Solids
Sorption to soil sediment, and other geologic solids is an important process that affects the fate, transport, and remediation of organic pollutants and pesticides in aquatic systems. This session seeks to bring together recent research on a variety of environmental science and engineering topics related to sorption processes, including the sorption of organic pollutants by soil or sediment from different media (e.g. water, air, organic liquids), sorption and desorption rate phenomena, the effects of chemical and physical heterogenities on sorption processes, the effects of surface-active agents on organic compound sorption, and the effects of rate-limited sorption on other fate processes, including biodegradation and chemical reaction. We particularly encourage submissions of fundamental research aimed at providing a better mechanistic understanding of the sorption process. Submissions describing either experimental data or model interpretations are welcome; however, studies which include both aspects are especially encouraged.

Conveners: William Ball, Dept. of Geography and Environmental Engineering, Johns Hopkins University, 313 Ames Hall, Baltimore, MD 21218-2686, Phone: +1-410-516-5434, Fax: +1-410-516-8996, E-mail: bball@jhu.edu; and James A. Smith, Dept. of Civil Engineering and Applied Mechanics, University of Virginia, Charlottesville, VA 22903-2442, Phone: +1-804-924-7991, E-mail: jas9e@virginia.edu

H12   Regional Estimation of Precipitation Extremes
The National Weather Service publications TP 40 (1961) and HYDRO-35 (1977), as well as the NOAA Atlas 2 (1973), are the primary sources of information on rainfall extremes in the United States. Considerable amounts of additional data have been collected since the publication of these documents, and improvements in analytical methods for the treatment of those data have also developed. In recent years, a number of efforts have been made to update and replace these reference publications. Unfortunately, those efforts have been restricted to only certain regions of the U.S., and there are various degrees of inconsistency among the approaches employed in different regions. This session will provide a forum for the exchange of information and ideas associated with regional estimation of precipitation extremes. Abstracts and presentations are solicited on new or advanced methods of precipitation frequency analysis, on methods of regionalization and spatial smoothing, on methods for the detection and treatment of the effects of potential climatic change, and one methods for effective dissemination of study results to the public and to design engineers. Contributions by investigators involved in current or recent regional studies are particularly encouraged.

Conveners: S. Rocky Durrans, The University of Alabama, Tuscaloosa, AL 35487-0205, Phone: +1-205-348-1710, E-mail: rdurrans@coe.eng.ua.edu; and Peter F. Rasmussen, INRS-Eau, Sainte-Foy, Quebec G1V 4C7 Canada, Phone: +1-418-654-2570, E-mail: rasmuspf@inrs-eau.uquebec.ca

H13   What is the Response of Aquatic and Terrestrial Ecosystems to Declining Levels of Acid Deposition?
Increased energy use efficiency and compliance with the 1990 Clean Air Act Amendments has resulted in declining levels of atmospheric acid deposition across large areas of North America. Recovery of surface waters from reduced acid loads, however, has lagged behind the changes in precipitation chemistry. In some regions, the pH and acid-neutralizing capacity of surface waters continue to decrease. This interdisciplinary session will explore the current status of acid deposition effects on aquatic and terrestrial ecosystems. Oral and poster presentations are solicited on topics dealing with, but not limited to: (1) long-term changes in the acid/base chemistry of surface waters; (2) the role of soil base depletion on forest health and the recovery of aquatic ecosystems; (3) the role of nitrogen deposition in the acid/base chemistry of surface waters; (4) the effects of decreasing loads of sulfur in atmospheric deposition on SO42- concentrations in surface waters; (5) implications of continued acid deposition on forest health; and (6) long-term changes related to atmospheric deposition in aquatic biological communities.

Conveners: Douglas A. Burns, U.S. Geological Survey, 425 Jordan Rd., Troy, NY 12180, Phone: +1-518-285-5662, Fax: +1-518-285-5601, E-mail: daburns@usgs.gov; and Gregory B. Lawrence, U.S. Geological Survey, 425 Jordan Rd., Troy, NY 12180, Phone: +1-518-285-5664, Fax +1-518-285-5601, E-mail: glawrenc@usgs.gov

H14   Hydrology and Water Quality in and Near the Everglades
In addition to their intrinsic natural value as unique ecosystems, the Everglades and its adjoining estuarine areas are critically important to tourism and water supply in south Florida. Approximately a century of drainage and development have reduced the size of the Everglades in half and created significant (in some areas, massive) changes in hydrology and water quality. Current research focuses on understanding fundamental hydrologic and geochemical processes in both heavily altered areas of the present-day system as well as more pristine portions of the remnant Everglades. Knowledge of both conditions is critical to current restoration efforts, as these efforts are driven largely by the hope that re-establishment of more natural hydrology and water quality will lead to restoration of ecosystem structure and function. Critical issues include restoration of natural water levels and flow rates, restoration of water quality (particularly nutrients and mercury), and control of exotic species such as Brazilian pepper and Melaleuca, while at the same time continuing water management for flood control and water supply purposes. Presentations on any aspect of hydrology or water quality of the Everglades or the surrounding estuarine environments are invited for this session, including field, laboratory, or modeling studies.

Conveners: David Genereux, Geology Department & Southeast Environmental Research Program, Florida International University, Miami, FL 33199, Phone: +1-305-348-3119, Fax: +1-305-348-3877, E-mail: genereux@fiu.edu; and David Krabbenhoft, USGS-WRD, 8505 Research Way, Middleton, WI 53562, Phone: +1-608-821-3843, Fax: +1-608-821-3817, E-mail: dpkrabbe@usgs.gov

H15   Influence of Coupled Processes on Solute Fate and Transport
Contaminant migration in subsurface environments is often governed by coupled processes such as biological transformations, oxidation-reduction reactions, chelation, precipitation, and adsorption. For example, metal-reducing bacteria can enhance solute transport via the reductive dissolution of Fe(III) oxide adsorbents. Alternatively, these same bacteria can help to immobilize contaminants via reduction to less soluble forms (e.g., Cr(VI) to Cr(III)). This session will explore the manner in which geochemical and microbiological processes combine to influence the mobility of contaminants in unsaturated and water-saturated porous media. Both experimental studies and studies that link observation with theory are encouraged.

Conveners: Scott C. Brooks, Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6038, Oak Ridge, TN 37831-6038, E-mail: 3sb@ornl.gov; and James E. Saiers, Department of Geology, Florida International University, Miami, FL, 33199, E-mail: saiers@fiu.edu

H16   Sources of Variation of Soil Moisture
Spatial and temporal variations of soil moisture are caused by (at least) variations in atmospheric forcing (~10 km, ~ 10 min), landsurface topography (100 m), and soil texture (1 m). The purpose of this session is to identify the relative role of each of these components at various volume averaging scales, and in doing so to try to clarify the relation and comparability of: 1) "point" soil moisture, which is at the appropriate scale to be transformed to energy potential and thus to be physically related to water uptake by plants and to (darcian) soil water flux; 2) grid averaged soil water storage in numerical models, especially global circulation, weather, and mesoscale models; and 3) soil water volumes estimated at various scales through remote sensing. Field, laboratory, model, and theoretical analyses are solicited.

Conveners: Guido D. Salvucci, Departments of Geography and Earth Sciences, Boston University, 675 Commonwealth Avenue, Boston, MA 02215, Phone: +1-617-353-8344, E-mail: gdsalvuc@bu.edu; and Marc Parlange, Department of Geography and Environmental Engineering, Johns Hopkins University, Ames Hall, Baltimore, MD 21218, E-mail: mbparlange@jhu.edu

H17   Regionalisation in Hydrology : The Role of Vegetation, Soils and Climate in Driving Catchment-Scale Hydrologic Response
The hydrologic response of catchments is controlled by a complex function of ecological, climatic, and geomorphic processes. Predicting the hydrologic response of ungauged catchments can be accomplished using regionalisation techniques, where the catchment under consideration is considered to behave similarly to other, gauged catchments. However, for such techniques to have wider application, hydrologic response needs to be understood in terms of the processes driving it, such as climate, vegetation, soils, and topography. The hydrologic characteristics being regionalised may be provided by a rainfall-runoff model, or they may be derived from long-term streamflow records without the use of a model, as is often the case for flood frequencies, annual water yields, or low flow characteristics. In either case, high quality, long-term hydrologic data are required in order to adequately define the hydrologic response of a catchment. This hydrologic response then needs to be related to its ecological, climatic, and geomorphic controls. Because there are many different approaches to regionalisation, and because these approaches are often region-specific, collaboration within the hydrologic community is especially important. This session represents a valuable opportunity to review the research being carried out and assess the potential applications and limitations of regionalisation techniques, particularly as related to inter-regional comparisons. We invite contributions dealing with all aspects of the regionalisation of hydrologic response. This includes contributions from the field of rainfall-runoff modelling, as well as from researchers examining long-term hydrologic, climatic, and vegetation data sets, such as are available at a number of Long-Term Ecological Research (LTER) and other sites.

Conveners: David Post, Department of Geosciences, Oregon State University, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97331, Phone: +1-541-758-7767, Fax: +1-541-758-7760, E-mail: post@fsl.orst.edu; and Qingyun Duan, GCIP Climate Project, NWS/NOAA, 1325 East-West Hwy, Silver Spring, MD 20910, Phone: +1-301-713-1018, Fax: +1-301-713-1051, E-mail: qingyun.duan@noaa.gov

H18   Remote Sensing of Precipitation
This special session will cover a broad range of topics related to the remote sensing of precipitation. The session will consist entirely of poster presentations. Papers are solicited on the estimation, validation, and particularly on the error and uncertainty analysis of precipitation measured by ground-based remote sensors, such as radar (e.g., NEXRAD WSR-88D), and satellite sensors (e.g., VIS, IR, SSM/I). Uncertainty analyses of ground-based sensors used for validation (e.g., raingauge, drop spectra devices, microwave links) are welcome as well. The session will highlight research and applications involving remotely-sensed precipitation. Presentations related to the GEWEX Continental Scale International Project (GCIP), the TOGA Coupled Ocean-Atmosphere Experiment (COARE), the Tropical Rainfall Measuring Mission (TRMM), and the Pan American Climate Studies (PACS), among other programs, are particularly encouraged.

Conveners: Matthias Steiner, Princeton University, Dept. of Civil Engineering and Operations Research, Princeton, NJ 08544, Phone: +1-609-258-4614, E-mail: msteiner@radap.princeton.edu; and Allen Bradley, University of Iowa, Institute of Hydraulic Research, Iowa City, IA 52242, Phone: +1-319-335-6117, E-mail: allen-bradley@uiowa.edu

H19   Anthropogenic Impacts on Desert Hydrology
The hydrology of arid areas differs considerably from the more humid environment in that surface flows figure prominently and indeed are a necessary prerequisite for the occurrence of groundwater recharge. This makes water supply and quality extremely vulnerable to any change in land use, development and urbanization. Excessive water load from gardening or sewage, the diversion of natural drainage by roads and contaminant releases are just some of the effects to be considered. The arid zone is coming under increased pressure though population increases and land reclamation and on the other hand (and in conflict to this trend) as a location for industrial hazardous wastes. These developments result in major changes of land use affecting the precariously balanced desert hydrology, which depends on a fine tuning of the surface morphology, ecology and rainfall pattern. Papers considering the impact of different scales and types of change in land use of the arid environment on the hydrological regime and on the possibility of siting facilities and repositories for hazardous materials are invited.

Conveners: Joel R. Gat, Department of Environmental Sciences & Energy Research, Weizmann Institute of Science, 76100 Rehovot, Israel, Phone: +972-8-9342610, Fax: +972-8-9344124, E-mail: cigatj@weizmann.weizmann.ac.il; and Ronit Nativ, Soil and Water Sciences, Faculty of Agriculture, Hebrew University of Jerusalem, P.O. Box 12 Rehovot, 76100 Israel, Email: nativr@agri.huji.ac.il

H20   Geomorphic Responses to Environmental Change
Understanding how drainage basins respond to changes in climate and land-use is vital for many applications, including watershed management, geoarchaeology, and studies of alluvial terrace stratigraphy. At the same time, knowledge of geomorphic responses to climate change on regional to continental scales is essential for distinguishing between signatures of tectonics and climate in the stratigraphic record. This session will focus on the mechanics of drainage basin adjustment to changes in climate, vegetation, and land-use, and the implications of those adjustments for large-scale sediment budgets. Submissions dealing with all aspects of drainage basin response, including stream erosion/deposition, channel-hillslope interactions, vegetation-erosion dynamics, and basin sediment yield are welcome. We especially encourage contributions dealing with (1) new data sets or techniques, (2) the role of hillslope-channel interactions, and/or (3) the link between watershed-scale processes and regional-scale sediment flux.

Convener: Rafael Bras and Greg Tucker, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, Phone: +1-617-253-7516, E-mail: gtucker@mit.edu

H21   Reactive Transport Modeling in Innovative Subsurface Remediation (Joint with G, V)
As innovative remediation technologies (IRTs) have become increasingly tenable alternatives for hazardous waste site cleanup, demand has grown for simulators capable of IRT assessment, design, and optimization. Rigorous treatment of geochemical reactive transport is required in many IRT simulators. This session will provide a venue for the discussion of approaches for reactive transport modeling applied directly to IRTs, including, but not limited to, reduced-iron reaction barriers, electrokinetics, and in-situ stabilization. Descriptions and comparisons of modeling approaches and issues of practical application are appropriate topics.

Conveners: Chris McGrath, USAE Waterways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199, Phone: +1-601-634-3798, Fax: +1-601-634-3129, E-mail: mcgratc@mail.wes.army.mil; and Steve Yabusaki, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, Phone: +1-509-372-6095, Fax: +1-509-372-6089, E-mail: sb_yabusaki@pnl.gov

H22   Groundwater Models: How Much Complexity Is Warranted?
Recent advances in computer hardware and software should result in commensurate increases in our ability to simulate the natural world. However, this increased capability has resulted in more time being expended constructing complex models. Often such effort can reduce the time spent on testing conceptual models and understanding the hydrogeology. These developments provide the setting for a session that asks the question: "Are we really improving our understanding of the systems being simulated?" Contributions are sought from both code developers and users to discuss recent advances in groundwater modeling, associated problems and solutions.

Conveners: Randy Hunt, US Geological Survey, 8505 Research Way, Middleton, WI 53562, Phone: +1-608-821-3847, Fax: +1-608-821-3817, E-mail: rjhunt@usgs.gov; and Chunmiao Zheng, Department of Geology, University of Alabama, Tuscaloosa, AL 35487, Phone: +1-205-348-0579, Fax: +1-205-348-0818, E-mail: czheng@wgs.geo.ua.edu

H23   Novel Interpretations and Modeling of Data Obtained From Fractured Rock: Hydraulic Test Results, Structural Data, and Solute Transport
There are increasing numbers of high-quality data sets containing detailed hydraulic testing results, structural (i.e. fracture orientation and position), and solute transport information presently being collected in a variety of fractured rock environments worldwide. Many of these data are now collected with the requirement of geostatistical interpretation in mind. In this session we encourage the presentation of papers describing novel cost-effective strategies for data collection or new methods for the interpretation of existing non-ideal data sets. Examples of the use of new data sets and interpretation in the simulation of flow and transport are also encouraged.

Conveners: Kent Novakowski, National Water Research Institute, 867 Lakeshore Rd., Burlington, ON, L7R 4A6, Canada, Phone: +1-905-336-4610, Fax: +1-905-336-4400, E-mail: Kent.Novakowski@CCIW.ca; and John Welhan, Idaho Geological Survey, Department of Geology, Idaho State University, Pocatello, ID 83204-8072, Phone: +1-208-236-4254, Fax: +1-208-236-4414, E-mail:welhjohn@isu.edu

H24   Low Frequency Climate Variability Signatures on Regional Hydrolometeorologic Variables: Implications to Hydrologic Forecasting and Planning (Joint with A)
Low frequency climate variability (LFV) at interannual (due to El Niño, North Atlantic Oscillation, etc.) to interdecadal time scales is very important for water resources management and planning (e.g., drought and flood mitigation measures). Extreme events that have major impacts on societal welfare such as, variations in the severity and frequency of droughts, floods, durations and intensity and wet and dry seasons are strongly related to LFV. Understanding the nature of hydrologic variability at these time scales and their connections to climate variability is a vital step towards formulating effective planning strategies. In this session we solicit papers on understanding the eleconnection of LFV on regional hydrologic variables (precipitation, temperature, streamflow, drought indices, etc.) from data analyses, modeling studies, and potential applications to forecasting and planning.

Conveners: Balaji Rajagopalan, Oceanography, Lamont-Doherty Earth Observatory, Columbia University, PO Box 1000, Rt. 9W, Palisades, NY 10964-8000, Phone: +1-914-365-8692, Fax: +1-914-365-8736, E-mail: rbala@rosie.ldgo.columbia.edu; and Ana Barros, 212 Sackett Building, Penn State University, University Park, PA 16802, Phone: +1-814-863-8609, Fax: +1-814-863-7304, E-mail: barros@essc.psu.edu

H25   Biotic Transformations and Biogeochemical Indicators of Metals in Natural Ecosystems
The purpose of this session is to present and discuss recent research on the interactions between metals and biota in natural ecosystems, with an emphasis on the roles that biota play in driving biogeochemical cycles and the information that biota can yield regarding the past and present occurrence and behavior of metals. Papers that address the following problems are particularly sought. What are the responsible organisms, mechanisms, rates, and controls on the biotic transformation and mobility of metals in natural ecosystems? Can biomonitoring techniques be used to elucidate metal bioavailability, exposure, and physiological effects? Do any organisms contain accurate and interpretable biorecords of historical metals contamination? The emphasis of this session is intended to be on mechanisms and processes in natural systems, both terrestrial and aquatic. Mechanistically-oriented studies in artificial systems may also be appropriate.

Conveners: Harold F. Hemond, R.M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, Phone: +1-617-253-1637, E-mail: hfhemond@mit.edu; Heidi Nepf, R.M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, Phone: +1-617-253-8622, E-mail: hmnepf@mit.edu; Daniel Brabander, R.M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, Phone: +1-617-258-6835, E-mail: dbraband@mit.edu; James Gawel, R.M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, Phone: +1-617-258-6835, E-mail: waterboy@mit.edu; and Katja Knauer, Dept. Chimie Analytique, 30 quai E. Ansermet, 1211 Geneve 4, Switzerland, E-mail: knauer@eawag.ch

H26   Student Showcase: National Science Foundation Graduate Research Traineeship Program in Hydrology
During the past five years, exciting multidisciplinary graduate research and training programs in the hydrologic sciences have been established by the National Science Foundation with grants to the University of Arizona, University of Minnesota, Columbia University, Rensselaer Polytechnic Institute, University of Cincinnati, University of Maryland, University of Colorado-Boulder, University of Texas-Austin, University of Virginia, and the Massachusetts Institute of Technology. This session provides NSF-GRT fellows with an opportunity to present their research projects in diverse areas, including the role of fluids in geologic processes, contaminant hydrogeology, and scaling relationships in the hydrologic sciences. This is a poster-only session.

Conveners: Holly C. Hartmann, Department of Hydrology and Water Resources, University of Arizona, P.O. Box 210011, Tucson, AZ 85721, Phone: +1-520-621-3973, Fax: +1-520-621-1422, E-mail: hollyh@hwr.arizona.edu; Marcia J. Tobin, Department of Earth and Environmental Sciences, Columbia University, Palisades, NY 10964, Phone: +1-914-365-8905, Fax: +1-914-365-8155, E-mail: mjt@ldeo.columbia.edu; and Elise Bekele, Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive, S.E., Minneapolis, MN 55455, Phone: +1-612-627-4777, Fax: +1-612-625-3819, E-mail: e_bekele@darcy.geo.umn.edu

H27   The Role of Preferential Flow as a Mechanism for Groundwater Contamination
Identification of groundwater contamination mechanisms is of significant concern from many perspectives. Contamination can result from agricultural and forestry use of pesticides, from land application of biosolids, from abandoned, operational and planned RCRA subtitle D landfills, from RCRA subtitle I underground storage tanks, and from low-level nuclear waste disposal facilities. A significant body of field data exists suggesting preferential flow through the vadose zone dominates contaminant movement into groundwater at these sites. Preferential flow appears to dominate transport regardless of soil texture or geologic setting. This session will provide a forum for the discussion of field studies focusing on transport resulting from non-point/point sources and what role preferential flow plays in the contamination of groundwater.

Conveners: R. Matzner, USEPA, MC 7507C, 401 M St., SW, Washington, DC 20460, Phone: +1-703-305-5975, Fax: +1-703-305-6309, E-mail: matzner.robert@epamail.epa.gov; and Todd C. Rasmussen, University of Georgia, School of Forest Resources, Phone: +1-706-542-4300, Fax: +1-706-542-8356, E-mail: trasmuss@smokey.forestry.uga.edu

H28   Environmental Geochemistry Posters
Posters are solicited on environmental geochemical techniques, including laboratory studies, field investigations, and modeling advances. A broad spectrum of topics are appropriate for this session including redox processes in wetlands, flowpath determinations using combined geochemical and hydrometric techniques, biogeochemical cycling, mineral weathering, degradation of organics, and site remediation efforts. Poster session only.

Conveners: Rick Hooper, USGS, 3039 Amwiler Road, Suite 130, Atlanta, GA 30360, Phone: +1-770-903-9146, Fax +1-770-903-9199, E-mail: rphooper@usgs.gov; and Carol Kendall, U.S. Geological Survey, 345 Middlefield Rd., MS 434, Menlo Park, CA 94025, Phone: +1-650-329-4576, Fax: +1-650-329-5590, E-mail: ckendall@usgs.gov

H29   Spatio-Temporal Dynamics of Soil Moisture and Subsurface Flow: Methods and Models for a Nonlinear System
Research from a wide spectrum of the earth science community is focusing on spatio-temporal dynamics of soil moisture, unsaturated/saturated flow and two-phase flow in porous media. In particular experimental and theoretical methods and models from the field of nonlinear dynamical systems are receiving much attention with applications in soil physics, hydrology, climate modeling, etc. Some of the approaches represented are: volume and ensemble averaging of local equations of unsaturated flow, issues of stability and bifurcation of equilibria, theory of chaotic dynamics, viscous fingering, hysteresis, dual porosity and fracture flow, space-time modal analysis of soil moisture/pressure in heterogeneous media and issues of spatial scaling. This session will provide a forum for theories and experimental methods which contribute to our understanding of the fundamental dynamics of moisture movement in the subsurface system.

Conveners: Christopher J. Duffy, Civil & Environmental Engineering Department, Penn State University, 212 Sackett Bldg., University Park, PA 16802, Phone: +1-814-863-4384, Fax: +1-814-863-7304, E-mail: cxd11@psu.edu; and David Brandes, Civil & Environmental Engineering Department, Penn State University, 212 Sackett Bldg., University Park, PA 16802, Phone: +1-814-865-5451, E-mail: dxb172@psu.edu

H30   Fundamentals of Snow and Ice Processes
Snow and ice are important components of the Earth's system. They are key factors in climatic variations on time scales ranging from seasons to millennia, and produce geomorphic changes in small alpine valleys and across major continents. Water contained in and released from snow and ice is important to local water resources and to global sea level changes. m Moreover, snow and ice present local hazards in terms of avalanches and outburst floods, and are important influences on ecosystems. Progress in glaciology (the study of snow and ice in all its forms), like the other sciences, is typically focused on small advances in understanding, and our meetings typically reflect this tendency. The purpose of this session is to take a wider view of the subject and provide the opportunity to re-examine some of our fundamental assumptions or to synthesize recent advances in a sub-field that addresses questions of a more general nature. Hopefully, this session will draw audiences from non-glaciological disciplines in addition to our glaciological colleagues. Presentations that address such topics are encouraged.

Convener: Andrew G. Fountain, Department of Geology, Portland State University, Portland, OR 97207-0751, Phone: +1-503-725-3386, Fax: +1-503-725-3025, E-mail: fountaina@pdx.edu

M01   Order-Disorder Phenomena in Mantle Minerals (Joint with T, V)
Most mantle minerals, including olivines, ortho- and clinopyroxenes, garnets, spinels, wadsleyites, and perovskites, display pressure- and temperature-dependent cation ordering. This ordering behavior may strongly affect physical and thermochemical properties, such as molar volume, elasticity, and electrical and thermal transport. Ordering may be especially significant in minerals that incorporate presumably minor mantle cations, including aluminum, ferric iron, calcium, titanium, and sodium. This special session will focus on the synthesis and crystal chemical characterization of high-pressure phases that display order-disoder phenomena, as well as the thermochemical and physical behavior of these phases.

Conveners: Hexiong Yang, Geopysical Laboratory, 5251 Broad Branch Rd., NW, Washington, DC 20015, Phone: +1-202-686-2410, ext. 2470, Fax: +1-202-686-2419, E-mail: yang@gl.ciw.edu; and Robert Hazen, Geopysical Laboratory, 5251 Broad Branch Rd., NW, Washington, DC 20015, Phone: +1-202-686-2410, ext. 2470, Fax: +1-202-686-2419, E-mail: hazen@gl.ciw.edu

OS01   Research and Applications in Hyperspectral Optics
A relatively new thrust in ocean optics is the collection and use of hyperspectral data. Newly introduced and emerging in-water instruments obtain optical information over multiple channels: ac-100s and 512-channel spectrometers are two examples. These in-situ sensors will serve as ground truth for high-flying hyperspectral sensors, as well as satellites to be launched within the next five years that will also be equipped with such sensors. This session will explore the lessons learned from recent deployments of these new hyperspectral instruments and the potential for the use of collected data in a variety of research and applications areas. Examples of such applications include ocean color research, coastal zone management, hazardous algal bloom assessment, hydrocarbon detection, and military optical systems support. Contributors from these and other disciplines are welcome.

Conveners: Alan D. Weidemann, Naval Research Laboratory, Stennis Detachment Code 7331, Stennis Space Center, MS 39529, Phone: +1-601-688-5253, Fax: +1-601-688-5379, E-mail: alanw@nrlssc.navy.mil; and Curtiss O. Davis, Naval Research Laboratory, Code 7212 Building 2, Room 210, Washington, DC 20375, Phone: +1-202-767-9296, Fax: +1-202-404-7453, E-mail: davis@proteus.nrl.navy.mil

OS02   Responses of Coastal Wetlands to Hydrologic Alteration and Restoration (Joint with H)
Coastal wetlands--which can act as storm buffers, fish nurseries, waterfowl habitat, and sinks for sediment, dissolved nutrients, and toxic contaminants--are steadily disappearing from the world's coastal zones. Natural and anthropogenic forces are all contributing to coastal-wetland degradation and loss, including subsidence, sea-level rise, coastal infrastructure development, and human alteration of ambient hydrologic, water quality, and sedimentary regimes. For example, deltaic wetland complexes around the world are drowning due to high rates of relative sea-level rise, subsidence, and sediment starvation caused by stream regulation; back-barrier marsh systems in many other areas (such as the eastern U.S. and northern Europe) have experienced filling, diking, and flow restriction. This session will explore the hydrologic, sedimentary, sea-level-change, and coastal-energy factors that favored coastal-wetland development during the Holocene, the effects of human interaction with these regimes in recent centuries, and the outcomes of present-day efforts to restore hydrologic processes in these critical coastal systems.

Conveners: Peter K. Weiskel, U.S. Geological Survey, 28 Lord Rd., Marlborough, MA 01752, Phone: +1-508-490-5026, Fax: +1-508-490-5068, E-mail: pweiskel@usgs.gov; and Judson W. Harvey, U.S. Geological Survey, 430 National Center, Reston, VA 20192, Phone: +1-703-648-5876, Fax: +1-703-648-5484, E-mail: jwharvey@usgs.gov

OS03   Fungi and Yeasts in the Marine Environment
Interest in fungi in the marine environment is steadily increasing, but the research results tend to be scattered over various journals and meetings. New marine fungi are reported on a regular basis and it is apparent that fungi occur throughout the oceans, including at locations such as the bottom of the Marianas Trough and polar areas. Fungi are particularly abundant in near-shore environments where their biomass can be much larger than bacterial or microalgal biomass. This session aims at evaluating and summarizing the findings of ongoing research and will provide inspiration and stimulating discussions, leading to a better understanding of the role of fungi in the marine environment and creating a valuable impulse for future research efforts. Contributions that help quantify the importance of fungi, especially in polar areas where data are still relatively scarce, or that focus on the role of fungi in biogeochemical processes and cycles are particularly welcome. Examples of the latter would be hydrocarbon utilization and metal scavenging (f.i. by cell wall chitin or extracellular enzymes, concentration of metals in vacuoles, or through redox reactions leading to precipitation).

Convener: Angelina W.M.G. Souren, Dept. of Chemistry, Geobiochemistry Group, Gorleaus Laboratories, RijksUniversiteit Leiden, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Phone: +31-71-527-4413 or +31-20-613-42-83, Fax: +31-71-527-4537, E-mail: beuf@geo.vu.nl

OS04   The Measurement of Sea Surface Temperatures From Satellites-Overview and Algorithm Intercomparisons
There are now several dedicated instruments for detecting sea surface temperatures (SST) from satellites, two of which include the Advanced Very High Resolution Radiometer (AVHRR), and the Along-Track Scanning Radiometer (ATSR). Both these instruments have now given us at least 4 years of overlapping data. An understanding of how to combine these data sets and their accuracies is critical if satellite derived SST's are to be used in global climate change studies. These two instruments use different algorithms in the measurement of SSTs. The NOAA/NASA AVHRR Oceans Pathfinder nonlinear algorithm determines SST via a least squares fit to a set of in-situ observations, while the ATSR instrument uses radiative transfer theory to measure a SST. Water Vapor and aerosols are also known to affect the measurement of SSTs from both instruments. Ancillary data, such as aerosol optical thickness, wind speed and water vapor are now available, over a period of several years, to examine the influence of these parameters on the SST retrieval. The session will focus on inter-algorithm comparison with emphasis on skin-bulk temperature differences and the influence of error sources such as water vapor and aerosols on the retrieval of SSTs. Papers on using other sensors for SST measurements, along with combining SSTs from different sensors, are also encouraged.

Convener: Jorge Vazquez, Ocean Science Element, PO.DAAC, Jet Propulsion Laboratory/Caltech, M/S 300/323, 4800 Oak Grove Dr., Pasadena, CA 91109, Phone: +1-818-354-6980, Fax: +1-818-393-6720, E-mail: jv@pacific.jpl.nasa.gov

OS05   Boston Harbor: The Experiment
Boston Harbor is a prime example of an urban estuary. Strong influences from marine, riverine, and anthropogenic processes interact to control atmospheric, aquatic, and sedimentary environments. Many of the scientific processes, societal issues, and economic pressures relevant to Boston Harbor, one of the best studied anthropogenically perturbed aquatic environments, are or will be relevant to coastal areas worldwide. Presently, dramatic changes in water and sediment quality are a product of scientific, societal, and political inputs. Papers regarding biological, chemical, physical, geological, or social aspects of Boston Harbor are invited. Topics involving measured or predicted changes to this dynamic and complex estuarine system due to improvements to the Deer Island sewage treatment system including the relocation of the outfall are especially welcome.

Conveners: Robert F. Chen, Environmental, Coastal & Ocean Sciences (ECOS), UMass-Boston, 100 Morrissey Blvd., Boston, MA 02125-3393, Phone: +1-617-287-7491, Fax: +1-617-287-7474, E-mail: chenr@umbsky.cc.umb.edu; G. Bernard Gardner, Environmental, Coastal & Ocean Sciences (ECOS), UMass-Boston, 100 Morrissey Blvd., Boston, MA 02125-3393, Phone +1-617-287-7454, Fax: +1-617-287-7474, E-mail: chenr@umbsky.cc.umb.edu; Judith Pederson, MIT, Sea Grant College Program, 292 Main Street, E38-300, Cambridge, MA 02139, Phone: +1-617-252-1741, Fax: +1-617-252-1615, E-mail: jpederso@mit.edu; and Eric Adams, MIT, Civil & Environmental Engineering, Parsons Lab, Main Street, 48-325, Cambridge, MA 02139, Phone: +1-617-253-6595, Fax: +1-617-258-8850, E-mail: eeadams@mit.edu

OS06   Stability of the Mesozoic and Cenozoic Tropics
It has been widely believed that throughout much of the Mesozoic and Cenozoic, tropical surface temperatures were as warm as those of today or even warmer. It has also been widely assumed that tropical ecosystems have been stable and diverse on both biological and geological timescales. Both beliefs have been challenged in recent years by new data interpretations and new modeling studies. Tropical processes set critical boundary conditions for global climate behavior and global patterns of biological diversity. Consequently, our understanding of Mesozoic and Cenozoic tropics provides important context for attempts to understand both future conditions and the relatively recent (in)stability of Quaternary oceans, climate and biota. We welcome presentations which address the issue of tropical stability from both modeling and observational perspectives.

Conveners: Steven D'Hondt, Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, RI 02882, Phone: +1-401-874-6808, Fax: +1-401-874-6811, E-mail: dhondt@gsosun1.gso.uri.edu; Dan Schrag, Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, Phone: +1-617-495-7676, Fax: +1-617-495-8839, E-mail: schrag@eps.harvard.edu; and Lisa Sloan, Department of Earth Sciences, University of California, Santa Cruz, CA 95064, Phone: +1-408-459-3693, Fax: +1-408-459-3074, W-mail: lcsloan@earthsci.ucsc.edu

OS07   Remote Sensing of Coastal Phenomena
Recent advances in remote sensing technologies now afford unprecedented means of characterizing fields within the coastal zone. These technologies include airborne and satellite-based optical and microwave instruments, shore and ship-based VHF radars and moored and ship-based acoustic devices. They indirectly measure many physical, chemical and biological parameters associated with fronts, plumes and other phenomena on a wide variety of spatial and temporal scales. We encourage submittal of papers which describe further technological advances but wish particularly to include papers which deal with synthesis of data from existing instruments. This includes but is not limited to multi-parameter data fusion, data assimilation into optical, bio-physical and/or hydrodynamical models, and related theoretical and numerical development.

Conveners: Jerry Miller, Ocean Sciences Code 7332, Naval Research Laboratory, Stennis Space Center, MS 39529, Phone: +1-228-688-4169, Fax: +1-228-688-5997, E-mail: jmiller@nrlssc.navy.mil; Lawrence Harding, Horn Point Laboratory, University of Maryland Center for Environmental Science, P.O. Box 775, Cambridge, MD 21613, Phone: +1-301-405-6372, E-mail: larry@kestrel.umd.edu; and Dennis Trizna, Sensing and Systems Division Code 321, Office of Naval Research, 800 North Quincy St., Arlington, VA 22217, Phone: +1-703-696-8380, E-mail: TRIZNAD@onr.navy.mil

OS08   Caribbean Sea Paleoceanography and Tectonic Evolution Since the Late Cretaceous: Marine and Terrestrial Records
The Caribbean Sea serves today as a narrow passageway for the surface return flow of the global thermohaline oceanic circulation and also occupies a unique tectonic position in the western hemisphere. The Caribbean Cenozoic sedimentary sections from cores, deep drill sites, and terrestrial outcrops have uniquely recorded tectonic events that have influenced the paleoceanography and paleoclimate of Earth, such as the uplift of the Isthmus of Panama, the rise of the northern Andes Mountains, the development of Central American arc volcanism, and the crustal movements responsible for the formation of the Cuba, Jamaica, Hispaniola, the Virgin Islands, and the Lesser Antilles. We solicit presentations that discuss paleoceanographic records targeting any age period since the late Cretaceous, and that provide fundamental data relevant to the evolution of the Caribbean ocean system, with global paleoceanogaphic and paleoclimatologic consequences. Terrestrial studies that complement these marine records are also encouraged.

Conveners: R.W. Murray, Dept. of Earth Sciences, Boston University, 685 Commonwealth Avenue, Boston, MA 02215, Phone: +1-617-353-6532, Fax: +1-617-353-3290, E-mail: rickm@bu.edu; and A.W. Droxler, Dept. of Geology annd Geophysics, MS-126, 6100 Main Street, Houston, TX 77005-1892, Phone: +1-713-527-4885, Fax: +1-713-285-5214, E-mail: andre@ruf.rice.edu

OS09   First Earth Science Results from NSCAT Data (Joint with A)
High resolution radar backscatter and ocean surface wind data from the NASA scatterometer (NSCAT) mission were released to the scientific research communities beginning in early 1997. The NSCAT data span the transition to the mature phase of the 1997 warm event of the El Nino/Southern Oscillation. The European Space Agency ERS-1 and 2 scatterometer data began in 1991 and are continuous to date. The NASA QuikSCAT mission is scheduled for launch in November, 1998. The scatterometer data provide unprecedented global and regional perspectives of the surface mesoscale variability in remote and often harsh environments. We encourage papers in all disciplines of earth science that make use of the new and growing scatterometer dataset in the forms of backscatter observations and/or derived 10m winds. We anticipate a number of papers emphasizing oceanic and atmopheric phenomena. We encourage submissions with applications in ice and surface vegetation studies as well.

Conveners: Ralph F. Milliff, Climate and Global Dynamics Division, NCAR, Boulder, CO 80307, Phone: +1-303-497-1393, Fax: +1-303-497-1700, E-mail: milliff@ncar.ucar.edu; and W. Timothy Liu, NASA Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109, Phone: +1-818-354-2394, Fax: +1-818-393-6720, E-mail: liu@pacific.jpl.nasa.gov

OS10   Radiocarbon as Tracer and Chronometer: Advances and Applications of Radiocarbon to Climate and Carbon Cycle Studies
The small sample size and high throughput capabilities of accelerator mass spectrometry have produced a number of advances in the use of radiocarbon to study oceanography, carbon cycling, organic matter geochemistry, and paleoclimates. Some of these include new high resolution records of the distribution and variability of radiocarbon in the ocean, measurement of specific components isolated from dissolved, sedimentary, or soil organic matter, and use of in situ production of radiocarbon to date geomorphic surfaces. The new data provide important constraints for models of carbon cycling, ocean circulation, and tracing anthropogenic CO2, as well as improved geochronologies for paleoclimate records. We invite papers presenting novel methodologies for radiocarbon sample preparation, new data sets, data interpretations, and applications.

Conveners: Susan Trumbore, Dept. of Earth System Science, University of California, Irvine, CA 92697-3100, Phone: +1-714-824-6142, Fax: +1-714-824-3256, E-mail: setrumbo@uci.edu; and Tom Guilderson, Dept. Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, and Center for Accelerator Mass Spectrometry, L-397, Lawrence Livermore National Laboratory, Livermore, CA 94550, Phone: +1-510-422-1753, Fax: +1-510-423-7884, E-mail:guilderson1@popeye.llnl.gov

P01   Cryovolcanic Resurfacing Processes
Based on Voyager observations, ice volcanism is widely predicted to occur on outer planet satellites. New high resolution Galileo data allow a reassessment of the role of cryovolcanism on these bodies, and its relationship to tectonic processes. In this session we wish to examine all aspects of cryovolcanic activity, including the geochemical constraints on the ascent of ice and ice-silicate magmas toward the surface, physical models of eruption, resulting surface morphologies, and methods for distinguishing cryovolcanic features. With Cassini en route to the outer solar system, and with the Galileo Europa Mission underway, this is the ideal time to consolidate our current knowledge about cryovolcanism and to refine predictions for future observations.

Convener: Louise Prockter, Dept. of Geological Sciences, Box 1846, Brown University, Providence RI 02912, Phone: +1-401-863-3485, Fax: +1-401-863-3978, E-mail: Louise_Prockter@Brown.Edu

P02   In-situ Exploration of the Martian Surface
This session will focus on the chemistry, mineralogy, geology, atmospheric properties, and resource potential of the Martian surface as determined by in situ robotic landers and rovers. Appropriate contributions to this session would include continued analyses from the recent Mars Pathfinder mission, re-analyses of Viking Lander data, and discussions of the measurement strategies and expected scientific return from the upcoming Mars-98 and Mars-01 lander and rover missions.

Convener: Jim Bell, Cornell University, Space Sciences Bldg, Ithaca, NY 14853, Phone: +1-607-255-5911, Fax: +1-607-255-9002, E-mail: jimbo@marswatch.tn.cornell.edu

P03   Current Topics in Venus Geology and Geophysics
Several years after the end of the Magellan mission, the geology and geophysics of Venus remain a topic of active study. An ongoing program of geologic mapping at the 1:5 M scale and a diverse range of data analysis and modeling activities have answered many of the questions posed prior to Magellan's arrival at our sister planet. Many more questions, however, have emerged from these data. This special session solicits abstracts on the surface and interior of Venus, with a special emphasis on emerging paradigms for crustal stratigraphy, the nature of surface/atmosphere interactions, tectonic and gravity analysis of major features, and potential future mission requirements.

Conveners: James R. Zimbelman, MRC 315, Smithsonian Institution, Washington, DC 20560, Phone: +1-202-786-2981, Fax: +1-202-786-2566, E-mail: jrz@ceps.nasm.edu; and James W. Head III, Dept. of Geological Sciences, Box 1846, Brown University, Providence RI 02912, Phone: +1-401-863-2526, Fax: +1-401-863-3978, E-mail: James_Head_III@brown.edu

P04   Elliptical Orbit Results from Mars Global Surveyor
The Mars Global Surveyor (MGS) spacecraft is currently in an elliptical orbit around Mars. The spacecraft is in the process of aerobraking to achieve a 400-km circular orbit from which it will globally map the planet for a full Mars year (687 days). While in the elliptical orbit, during aerobraking and hiatus periods, the spacecraft instruments have collected observations that address fundamental aspects of the nature of the Martian solid planet, atmosphere, cryosphere and magnetosphere. We invite contributions that use MGS data to further understanding of the structure and evolution of Mars and the nature of its environment.

Conveners: Arden A. Albee, Division of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125, Phone: +1-818-395-6367, Fax: +1-818-354-8862, E-mail: aalbee@cco.caltech.edu; and Maria T. Zuber, Dept. of Earth, Atm. and Planetary Sciences, MIT, Cambridge, MA 02139, Phone: +1-617-253-6397, Fax: +1-617-258-9697, E-mail: zuber@mit.edu

S01   Seismological Studies of the Continental Tectosphere
The continents comprise assemblages of crustal and mantle rocks that have experienced a complex history of magmatism and metamorphism. In the ancient cratons, the mantle component of this tectosphere appears to be exceptional thick (>200 km). Various models have been proposed to explain the origin and evolution of continental deep structure and its involvement in plate tectonics, mantle convection, and other dynamical processes, but a number of the basic issues have yet to be resolved. New insights into these problems are being obtained from seismological studies of subcontinental structure, especially from data sets collected by high-density, temporary deployments of broadband seismometers. The purpose of this session is to compare the results from seismological studies of the continental mantle and discuss their implications for dynamical and evolutionary models. The aspects of continental structure to be considered include high-resolution tomography, seismic anisotropy, the structure of upper-mantle discontinuities, scattering by small-scale heterogeneities, and petrological controls on density and seismic velocities.

Conveners: T.H. Jordan, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Rm 54-918, Cambridge, MA 01239, Phone: +1-617-253-3382, E-mail: thj@mit.edu; and M. Bostock, Department of Earth and Ocean Sciences, University of British Columbia, 2219 Main Mall, Vancouver, BC V6T 1Z4, Canada, Phone: +1-604-822-2082, E-mail: bostock@geop.ubc.ca

S02   Recent Advances in Theoretical Seismology
The amplitudes and arrival times of seismic waves contain important information about the Earth's interior, making seismology one of the cornerstones of global geophysics. Over the past decades, advances in theoretical seismology, coupled with improved data quality, station coverage and computing capabilities, have led to major breakthroughs in understanding our planet. The purpose of this special session is to give an overview of current techniques in theoretical seismology, and to provide a forum for the discussion of its future. Topics related to the study of body waves, surface waves and free oscillations in laterally heterogeneous Earth models, particularly in the context of tomographic inversions, are invited.

Conveners: J. Tromp, Department of Earth and Planetary Sciences, Harvard University, Hoffman Lab, 20 Oxford Street, Cambridge MA 02138, Phone: +1-617-496-5344, E-mail: tromp@geophysica.harvard.edu; and L. Zhao, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Rm. 54-922, Cambridge, MA 01239, Phone: +1-617-253-3786, E-mail: li@quake.mit.edu

S03   Source Characterization in the CTBT Context Using Seismic and Other Acoustic Technologies
An international effort is currently underway to implement an International Data Center (IDC) that will enhance capabilities to monitor nuclear testing, as well as to support effective implementation and compliance with nuclear testing treaties under the Comprehensive Test Ban Treaty (CTBT). Papers are invited on the development and application of methods aimed at improving source characterization (e.g., location, magnitude/moment, focal mechanism) using regional networks/arrays and global networks, possibly in complex settings, within the context of global monitoring of the CTBT using seismic, hydroacoustic and infrasound data.

Conveners: E.R. Engdahl, U.S. Geological Survey, N.E.I.C., P.O. Box 25046, MS 967 DFC, Denver, CO 80225, Phone: +1-303-273-8422, E-mail: engdahl@gldfs.cr.usgs.gov; A. Cogbill, Geophysics Group, Los Alamos National Laboratory, P.O. Box 1663, MS C335, Los Alamos, NM 87545, Phone: +1-505-667-1049, E-mail: ahc@lanl.gov; and R. North, Center for Monitoring Research, 1300 North 17th St., Suite 1450, Arlington, VA 22209, Phone: +1-703-276-7900, E-mail: north@cmr.gov

S04   Shear-Wave Splitting Measurements and Interpretation: In Search of Consensus
Over the last decade observation and measurement of shear-wave birefringence has emerged as a routinely applied tool in seismological investigations. Interpretation of these measurements in terms of anisotropic crustal and mantle structure is far from routine, however, as widespread application of these techniques has revealed numerous cases where certain common assumptions (e.g., single layer of anisotropy with horizontally oriented hexagonal symmetry) do not seem to hold. It is now commonly observed that shear-wave splitting has azimuthal variability, and anecdotal evidence abounds that splitting measurements are sensitive to frequency content, time window, noise level, etc. In this session we would like to facilitate the exchange of experiences and ideas in both making the observations of shear wave splitting, as well as in interpreting the results in terms of physical properties of the medium. We seek presentations documenting or comparing techniques of measurement and error estimation, modeling shear waves in complex earth structures that lead to "split" phases, documenting observed complexity (or the lack of it) in shear-wave splitting, and so on.

Conveners: V. Levin, Yale University, Dept. Geology and Geophysics, P.O. Box 208109, New Haven, CT 06520-8109, Phone: +1-203-432-3279, E-mail: vadim@love.geology.yale.edu; and J. Gaherty, School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332-8340, Phone: +1-404-894-3893, E-mail: gaherty@quake.mit.edu

S05   The Lower Half of Earth's Mantle (Joint with G, GP, M, T, V)
The bottom half of Earth's mantle may contain many keys to understanding mantle convection and differentiation. Recent advances in seismic imaging revealed diverse structural features from the mid-lower mantle down to the core-mantle boundary (CMB); these include evidence for mid-mantle slab-like features that may disintegrate at large depths, increased heterogeneity near CMB with evidence for anisotropy and layers of ultra-low velocity, small-scale scatterers of seismic energy throughout the lowermost mantle, and disproportionality between P and S wave speeds at depth larger than approximately 2000 km. Reconciling these phenomena with theoretical and experimental studies of mantle convection and high pressure mineral physics, the (noble gas) isotope record, and with observations of Earth's magnetic field remains a challenge due to model uncertainties, experimental limitations, and the diversity in the various seismic model features. This session invites contributions from all disciplines and aims to assess the pertinent evidence and further elucidate our understanding of the structure, dynamics, and evolution of Earth's lower mantle.

Conveners: E. Garnero, Seismological Laboratory, University of California, 475 McCone Hall, Berkeley, CA 94720-4760, Phone: +1-510-643-3980, E-mail: eddie@s