Meeting Highlights

Union

U51A
Union Tutorials The Union Tutorials are a relatively recent, but highly popular, addition to the Fall Meeting. The concept is to pick four subjects that will be widely discussed at the meeting. The Tutorial Session offers lectures that provide introductory background to the subjects and underscore the key open scientific questions. The target audience is student members and regular members from other fields. Ideally, attendance at a Tutorial lecture would jump-start the attendee in understanding more technically detailed presentations on the subject elsewhere in the meeting. This year our Tutorials cover subduction zones in the crust and mantle (Douglas Wiens, Washington University), applications of the Global Positioning System (GPS) (Geoffrey Blewitt, University of Nevada, Reno), abrupt climate change (Jonathan Overpeck, University of Arizona), and extraterrestrial water (James Kasting, Penn State University).

U52A, U61A
New Dimensions in the Visualization and Management of Large Geophysical Data Sets Recent advances in computer and graphics processors, display devices, and the software needed to take advantage of this hardware, are revolutionizing the way that we can display, verify, analyze, and interact with the massively large data sets often associated with modern remote sensing or modeling techniques. These sessions highlight these new advances by bringing together presentations from researchers representing a broad spectrum of geophysical fields (Earth, ocean, atmosphere, and space) who are using the latest in advanced interactive and 3-D visualization techniques. The emphasis is not on the details of the graphics hardware or software but rather on the new scientific insights provided by using advanced visualization techniques.

U52B
Frontiers of Geophysics: A Vision for the Future of Environmental Research: Creating Environmental Intelligence Centers How can the geophysical sciences respond to the growing demands from society for information and "forecasts" upon which to base policy decisions. Eric Barron, Penn State University, presents a vision and a strategy for addressing both the scientific and social challenges. The vision involves a regional framework as a stepping-stone to a comprehensive national or global capability, and a demanding level of discipline to "forecasting" in a broad arena of environmental issues. The regional vision is designed to address a broad range of current and future environmental issues by creating a capability based on integrating diverse observing systems, making data readily accessible, developing an increasingly comprehensive predictive capability at the spatial and temporal scales appropriate for examining societal issues, and creating a vigorous intersection with decision-makers. With demonstrated success over a few large-scale regions of the United States, this strategy could lead to a national capability that far exceeds current capabilities.

U61B
Remote Detection of the Ingredients of Life These presentations will provide the current state-of-the-art technology for the detection of life on other planets and moons of our solar system. The emphasis is on Mars and Europa and the newest results (e.g., Odyssey Mission) on past and present habitable zones on these planetary bodies. Emphasis is also placed on the newest and developing technology on how to detect life including detection using chirality, biosignatures of very primitive life such as algae and fungus, and the possibility of thermoautotrophic life and its detection.

U62A, U72B
From Geodynamics to Complexity: Innovative Ideas in the Geosciences. These sessions feature outstanding poster and oral presentations in seismology, geodynamics, geochemistry, the planetary sciences, and the applications of fractals and self-organized criticality to the Earth sciences, all with the umbrella theme of "innovative ideas in the geosciences." Invited speakers include Claude Allegre, Don Anderson, Thomas Jordan, and Sean Solomon. This session is inspired by the scientific contributions of Donald L. Turcotte, who, over the course of a long and highly distinguished career, has made many historically important and lasting contributions to several areas in the Earth and planetary sciences.

U71A, U72A
Recent Changes in the Polar Latitudes: Evidence of Global Warming? Evidence of climate change is already becoming apparent in the higher latitudes of the globe. Snow, ice, and frozen ground dominate the polar latitudes, and climatic warming yields dramatic changes and substantial impacts. There are many reasons for these changes to occur and for the evidence to be documented at this time. For parts of the year, large areas of the Arctic and Antarctic have temperatures near 0C, the phase change temperature of water and ice. As temperatures become warmer or remain warmer for longer periods, many physical and biological changes occur. Glaciers melt, sea ice and ice sheets degrade, permafrost thaws, and the ecosystem responds to these threshold changes in the physical environment. This Union session has drawn experts from many specialties and from around the world to present evidence of rapid change. Although any individual indication of change may not provide proof of global warming, the cumulative conclusion from the combined evidence may be that the Arctic and Antarctic are entering states not seen in recorded history.

U72C
Who Will Do Geophysical Research in the Future? This session highlights the projected status of the Earth and space science workforce in the next two decades and discusses strategies to promote the continued health of this community in the future. The increasing relevance of Earth and space science research to society and the upcoming retirement of a significant number of scientists in these fields indicate that there will be ample job opportunities in these professions in the near future. Yet recent statistical studies on the numbers of students entering and obtaining degrees in these fields have caused growing concern that there will be insufficient young scientists to fill these positions. It appears that the Earth and space sciences are no longer as attractive as they once were to the traditional audience of young white males. In addition to fundamental shifts in demographics of young people, the growth of alternative careers such as computer science and the social and financial incentives to pursue medicine, business, and law instead of science are likely important factors in determining how many students elect to study the Earth and space sciences. Further, while there has been some progress in attracting women to the Earth and space sciences, the fields have an exceptionally poor track record when it comes to recruiting and retaining groups that reflect the full diversity of society. This session will highlight the changing demographics of the scientific workforce, review the current status of the educational pipeline, and discuss new strategies for ensuring an adequate number of high-caliber scientists and professionals in these fields in the future.

U11B
The Future of Nuclear Energy: An Evaluation in a Global Context Societies of the 21st century will increasingly use a more diverse mix of energy sources, possibly including nuclear, as petroleum supplies diminish. This session will address the scientific issues, including the need for future scientific studies, that would result from increased reliance on nuclear energy. Topics to be addressed, from both the domestic and international perspective, include the status and potential future trends in the use of nuclear energy; challenges associated with power plant security; the storage, disposal, and transportation of nuclear waste; the promise of new technologies; a review of international strategies for nuclear energy management; climate impacts associated with energy mix changes; and the role and responsibility of the geoscientist in influencing public opinion and debate about highly charged societal issues. Special panelists will include Shirley Jackson, President of Rensselaer Polytechnic Institute, and Ernest Moniz, Department of Physics, MIT.

U11A, U12A
Advances in Experimental and Observational Earth Sciences From the Use of Community-Based Facilities Advances in electronics, material science, sensor technology, energy sources, and communication systems have provided Earth scientists with an expanding assortment of sophisticated tools for investigations of the structure and properties of Earth and its constitutive materials. Over the past few decades several agencies have encouraged research communities to pool their resources in consortia and shared facilities and set priorities to enhance the infrastructure for experimental research. A primary purpose of these organizations has been to maintain a high level of discovery and productivity of Earth scientists by ensuring that necessary research equipment and access to advanced national, multiuser facilities are available to the community. The objective of this session is to explore the ways in which these facilities have supported and stimulated scientific advances in the Earth sciences and encouraged multiuser and multidisciplinary investigations. Presentations describe recent advances in experimental and observational Earth sciences and highlight the impact of improved research tools, facilities, consortia, and centers, and particularly major community-based facilities.

U12B
Agency Lecture: The Future of Global Climate Change Research: Key Issues Emerging From the Dec. 3-5 Washington, D.C. Workshop James R. Mahoney, Director, U.S. Climate Change Science Program, will discuss how research activities under the U.S. Global Change Research Program will be accelerated over the next 2-5 years in response to the Climate Change Research Initiative and what that means for U.S. researchers and their international partners. Mahoney will discuss what the Strategic Plan for climate and global change studies means to the research community, and how the USGCRP/CCRI program will integrate research across federal agencies with the goal of supporting climate change policy and resource management.

U21B
Outstanding Questions About Earth and Space a Half Century After IGY What new and challenging scientific questions have emerged since IGY? This session explores not only the outstanding scientific issues, but also the increased interconnection between geophysical research and public and social policy that has developed in the last 50 years and that provides the context for the future. Presentations span a range of topics including solid and fluid Earth, atmosphere, space, planetology, biosphere, and social context. Speakers have been encouraged to suggest ambitious ideas for how to advance the science and promote unselfish cooperation in research.

U21A, U22A
Carbon Sinks and Carbon Management: Scientific Perspectives on Potential Benefits and Consequences The oceans and terrestrial ecosystems are currently sequestering large amounts of carbon derived from anthropogenic carbon dioxide. These sessions focus on current and potential future benefits and consequences of a broad range of carbon sequestration and carbon management options, including environmental and socioeconomic effects of both deliberate and "natural" sequestration processes.

Atmospheric Sciences

A51A
Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET) Summer 2000 and Summer 2001 Measurements Intensives The PROPHET Summer 2000 and Summer 2001 Intensives included determinations of NO2, NOy, PAN, PPN, MPAN, HONO, isoprene nitrates, HNO3, OH, HO2, peroxides, O3, H2SO4, VOC, OVOC, and CO mixing ratios, VOC vertical profiles, isoprene fluxes, CO2 fluxes, H2O fluxes, aerosol size, composition and fluxes, UV radiation, photolysis frequencies, convective boundary layer characteristics, air mass trajectories, and meteorological parameters. Conclusions are presented regarding the effects of boundary layer dynamics, mixed layer height, flow regimes, and source regions on reactive nitrogen, oxidant, and aerosol levels and distributions; reactive nitrogen partitioning; anthropogenic and biogenic reactivity; and ozone production. Insights gained from a several-year record of isoprene flux measurements are also presented, including physiological controls on isoprene emissions; use of the surface energy flux, rather than temperature and light, in model estimations of canopy-scale isoprene emissions; and use of inverse lagrangian dispersion analysis to infer isoprene sources and sinks. A new focus on atmosphere-forest nitrogen exchange and forest cycling of nitrogen and carbon is introduced.

A51D, A52E, A61D, A61F, A62A, A62B, A72E, A11A, A12C
Transport and Effects of Anthropogenic Pollutants across the Pacific The importance of the intercontinental transport of air pollutants has been increasingly recognized. Anthropogenic emissions from industrial and biomass burning sources are largely localized in the boundary layer of the continents. Transport of these emissions to the troposphere as a whole has significant impacts on global climate and on air quality in downwind continents. Three major field campaigns (ACE-Asia, TRACE-P, and ITCT 2K2 including PEACE) have been conducted in the Pacific region during the last 2 years. The focus of each of these studies is the springtime outflow from Asia and its transport across the Pacific. Particular emphasis is placed upon ozone and its precursors, aerosols and their precursors, and long-lived greenhouse gases. These sessions will present the quantitative description of these phenomena that is beginning to emerge from the results of these three studies.

A51E, A61A
Aerosol, Cloud, and Tropospheric Chemistry Papers in these sessions will present laboratory experimental, field observational, and numerical modeling results on physics and chemistry of aerosols and clouds as well as on tropospheric chemistry. The roles of aerosol and cloud in tropospheric chemistry as well as in climate change will be emphasized.

A52B
Air Toxics: Regional Assessments Through Atmospheric Monitoring or Modeling Air toxics refer to hazardous air pollutants that have chronic effects on human health such as respiratory damage, birth defects, and cancer. Determining their atmospheric concentrations and deposition is then a vital interest, but low concentrations, long lifetimes, and complex processes make the goal difficult. This special session presents methods and knowledge used to overcome these problems for mercury, heavy metals, dioxins, and persistent organic pollutants.

A61C, A71H
Recent Advances in Global Climate Modeling These sessions look at the very early development and application of climate models including NCAR's climate models. Warren Washington's influence on the models is traced from the beginning to the present as well as his interaction with other investigators. Papers include discussions of paleoclimate, ocean and sea ice, solar and greenhouse gas forcing, the anthropogenic haze that spreads over south Asia and the northern Indian Ocean, and the remarkable feat of developing coupled climate model simulations.

A71F, A12F, A22B
Chemistry and Microphysics of Aerosol Particles Aerosol particles play an important role in the Earth' radiation balance. In this session papers on various areas of aerosol/cloud chemistry and physics are presented. The chemical and physical interactions between organic and/or inorganic molecules and aerosol particles are discussed. A number of presentations focus on the microphysics of ice formation from aerosol solutions of various compositions. Another group of papers discusses new information on the chemical composition of atmospheric aerosols. Remote sensing and modeling of atmospheric aerosols are also addressed.

A72A, A12E
Polar Air Chemistry: Past and Present These sessions bring together the latest findings from atmospheric chemists learning about the unusual chemistry that has been discovered in the polar boundary layer and from ice-core chemists trying to understand how the atmosphere has evolved over time. New results show how the top layers of snowpacks are significantly affecting the composition of the overlying atmosphere. Modeling makes it possible to back out past atmospheric compositions of important gases from ice-core data. New interpretations of aerosol chemistry in ice suggest that we may be able to link major changes in Antarctic climate with changes in external environmental factors (such as sea ice and South American climate) over hundreds of thousands of years.

A11B, A22D
The Northern and Southern Annular Modes These sessions include papers explaining the dynamics underlying the annular modes and the coupling of these modes to the oceans and stratosphere. This year particular emphasis will be placed on the Southern Annular Mode, with talks examining its dynamics, its response to stratospheric ozone depletion, and its role in glacial climates. Other speakers will discuss the response of the annular modes to human influence and the exploitation of their coupling with the stratosphere for improved long-range weather forecasts.

A11E, A12A
Carbon Cycle Science: The North American Carbon Program. The North American Carbon Program (NACP) is a multiagency attack on questions relating to the sources and sinks of carbon in North America. The research focuses on the three most abundant carbon gases in the troposphere: carbon dioxide, methane, and carbon monoxide. The program is driven by the need to know if North America is a consistent sink for carbon dioxide and is a major component of the U.S. Carbon Cycle Science Program and the U.S. Climate Change Research Initiative. Integration between diverse disciplines, combinations of new research techniques and monitoring, and numerical modeling will be used to delineate the mechanisms controlling these important gases. The sessions will present current plans for measurement systems, field campaigns, and model-data fusion, along with recent studies on the carbon budget.

A11F, A12G, A22C
New Developments and Needs in Laboratory, Field, and Modeling Efforts to Characterize the Physical, Chemical, and Optical Properties of Tropospheric Aerosols Ambient particulate matter in the atmosphere can affect the Earth's radiation budget through the scattering and absorbing radiation and by modifying cloud properties. These sessions focus on the physical, chemical, and optical properties of tropospheric aerosols. Water-ice-particle relationships are examined, as well as particle emissions from wild fires and anthropogenic combustion. New developments in measurement techniques and future measurement needs for determining aerosol properties and distributions are also addressed.

A21D, A22A
Climate Processes in the Tropical and Subtropical Eastern Pacific Analysis of oceanic and atmospheric observations obtained in the eastern tropical and subtropical Pacific using moorings, aircraft, and ships will be presented and compared to satellite data and models. Air-sea interactions will be discussed in the context of precipitating storms in the ITCZ, the cross-equatorial region and the SST front, and the stratus deck. Additionally, new information on cloud microphysical characteristics and cloud radiative feedbacks for tropical deep convective and stratus clouds will be presented.

Biogeosciences

B51C, B52A
Mechanisms of Carbon Stabilization and Loss in Soils Quantifying the physical and biological mechanisms that protect and preserve carbon in soils is critical to understanding the fate of carbon in response to anthropogenic and natural disturbances. These sessions will present papers organized around four functional themes: (1) mineralogy and physiochemical protection; (2) biological controls, including microbial, root, and organic matter quality; (3) climatic interactions; and (4) land-use interactions, such as physical disturbance, fire, and nutrient limitations. Papers will address these themes across spatial scales ranging from the individual clay mineral to the ecosystem and up to the regional and continental levels.

B52B
Merging Molecular Techniques and Genomics with Biogeochemistry This session will highlight the application of recently developed molecular level analytical techniques as well as genomic approaches to understanding biogeochemical processes in aquatic and terrestrial environments. Techniques to be discussed include synchrotron X-ray spectroscopy, compound specific isotopic analysis, mass spectrometric detection of unique metabolites, real- time PCR detection of specific catabolic genes, lipid biomarker analysis, and comparative genomics. Many of the presentations will place significant emphasis on the use of these tools for evaluating biogeochemical conditions relevant to remediation of contaminated sites. Other presentations will provide insights into the evolution of ecosystems as revealed by genomic analyses.

B52C, B71B
Life and the Evolution of the Earth System: Processes and Theories What were the environmental conditions in which life evolved in? And are there any general principles by which life affects the Earth system? The study of these questions necessarily involves some fundamental considerations of the biogeochemical cycles, how they are connected to the atmospheric greenhouse, how they have evolved over time, and how they are affected by life. Papers focus on new theoretical approaches to understanding the effects of life on Earth system functioning and quantification of the environmental conditions and challenges to early life and how it is recorded in geological archives.

B62A
Terran and Synthetic Environments: Where in the Solar System Can They Take Us? Speakers will highlight the latest results in uniquely severe environments and their relevance to life on other planetary bodies. Topics will include life from the visually exciting Lost City Hydrothermal Field (perhaps the closest link to biological activity of nascent life on Earth), life at the extremes of pressure and temperature, and deep subsurface microbes that may get their energetic foodstuffs from radiolytic reactions with water and sulfide. This expansion of the known envelope for life will be related to the potential for extraterrestrial life in places such as the high-radiation environment of Europa and the organic "soup" on Titan.

B71C, B72C, B11C, B12B
Water, Energy, and Carbon Exchange in Forest Systems These sessions cover carbon, water, and energy exchange determined by tower flux studies, and simulation modeling at various spatial and temporal scales. Topics include two-dimensional airflow in hilly terrain, ecological controls on carbon dioxide exchange by boreal forest stands recovering from fire, soil carbon dioxide fluxes in relation to stand age and soil diffusivity, modeling productivity in complex forest landscapes, and regional-scale isotopic discrimination and regional- and continental-scale carbon dioxide fluxes.

B72D, B11D, B11E, B12A
Interactions of Permafrost With Climatic, Hydrologic, and Ecosystems Processes The broadest impacts of a changing climate on the terrestrial Arctic regions will result from consequent effects of changing permafrost structure and extent. Climatic warming is becoming evident in permafrost records across the Arctic and in the Antarctic. As the climate differentially warms in summer and winter, the permafrost will become warmer and the active layer (the layer of soil above the permafrost that annually experiences freeze and thaw) will become thicker. These simple structural changes will affect every aspect of the surface water and energy balances and thus every biotic process occurring there. These sessions bring together experts in many disciplines from around the world to discuss the interdependence of climatic, ecologic and hydrologic processes in areas influenced by permafrost and how these processes will change as permafrost warms or degrades.

B11B, B22E
Aqueous Microbial Geochemistry: Extreme and Contaminated Environments These sessions showcase the application of powerful new techniques in microbial geochemistry spanning subglacial, thermal hot springs, acid mine drainages, hydrothermal vents, South African gold mines, and seafloor ocean crust environments. Microbial metabolic processes and reaction mechanisms will be linked to biogeochemical cycling of heavy metals, radionuclides, and explosives. The cycling of conventional energy sources in acidic, alkaline, thermophilic, and psychrophilic environments will also be explored. This session provides new insight into one of the most exciting frontiers of biogeosciences: environmental microbial geochemistry.

B21D, B22A, B22C
The Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) The Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) is a cooperative multinational Earth system science research project led by Brazil. The goal of LBA is to understand the role of Amazonia as a regional entity in the Earth system. LBA researchers will present about 50 talks and posters that deal with carbon cycling, atmospheric chemistry and trace gas exchange, land use and land cover change, and the physical climate of the Amazon region. Linkages among these areas are critical. It is clear from LBA results to be presented that interannual variations in climate control carbon fluxes and trace gas exchanges. Emissions of trace gases and especially aerosols have a strong influence on regional climate. Understanding the function of the Amazon will require robust models based on an understanding of local processes. Numerous detailed process studies complement the regional analyses presented in these sessions.

Cryosphere

The Cryospheric Sciences Focus Group (formerly the Snow, Ice, and Permafrost Technical Committee) is sponsoring four dynamic sessions at the Fall Meeting. These will cut across the themes of climate dynamics, environmental change, and cryospheric processes, with posters and talks that embrace seasonal snow, glaciers and ice sheets, ice shelves, freshwater ice, and sea ice.

C51A, C52A
Recent Changes in the Antarctic Ice Sheet, Natural Variability, and Global Warming Both the obvious and the obscure will be featured. MacAyeal (C52A-03) will present a mechanical analysis of the catastrophic breakup of the Larsen B Ice Shelf, with analogies to sumo wrestling, that has implications for paleoclimatic events elsewhere. That such connections might be made is due in part to the rare opportunity to observe not only the breakup events but their ocean-sediment signal in the making (Domack, C52A-04). Less visually dramatic changes, on the undersides of 25 of the largest Antarctic outlet glaciers, are equally profound. Rignot and Jacobs (C52A-01) use satellite radar interferometry and other data to infer basal melting rates and draw a correlation to warming seawater temperatures. They conclude that the warming-induced melting rates used for IPCC predictions may significantly underestimate this contribution to future sea level rise.

C52B, C61A, C62A, C12A
Glaciers and Ice Sheets Dramatic changes in glacial systems are also featured, with Steffen et al. (C52B-04), Jezek et al. (C52B-03), and Arendt et al. (C61A-06) introducing innovative new techniques to quantify ice shelf, ice sheet, and glacier thinning. Arendt et al.'s study of changes in Alaskan glaciers since the 1950s offers convincing evidence that sea level rise due to glacier melt is much greater than previously thought, echoing Rignot and Jacobs's observations from Antarctica (C52A-01). These sessions also focus on one of the outstanding challenges in glacier and ice sheet dynamics: theoretical and numerical articulation of glacier hydrology. Flowers et al. (C61A-02) present initial results from the most sophisticated model of ice sheet hydrology developed to date, while several other talks and posters examine englacial and supraglacial hydrology and outburst flood dynamics. Other research frontiers in glacier and ice sheet dynamics are well represented, including the mechanical properties and thermodynamics of firn and ice (e.g., Castelnau et al., C61A-09; Rempel, C61A-10; Wilen et al., C62A-0910).

C72A, C11B
The Role of Microstructure and Layering on the Physical Properties, Metamorphism, and Deformation of Snow Covers These sessions examine the influence of snow microstructure on snow physical, metamorphic, and mechanical processes, with applications in climate models, avalanche forecasts, and snow geophysical and engineering problems. Oral presentations are thematically combined with snow physics papers in sessions C72B and C11A, with featured talks that include a detailed review by Warren of optical properties and snow grain effects on radiative transfer in snowpacks (C72A- 03). German presents molecular-scale sintering studies (C72A-02), while Sturm and Pfeffer consider the spatial heterogeneity of snow microstructure and snowpack layering and the implications for macroscopic behavior (C72A-01; C72A-04).

C72B, C11A
Snow and Ice in the Earth System Observational and model-based studies of cryosphere-atmosphere interactions are featured, with a strong emphasis on snowpack ablation processes. Pomeroy (C72B-04) discusses field experiments that demonstrate that the sublimation of snow is a nonnegligible component of surface energy and mass balance in high-latitude snowpacks. A number of additional contributions present new results on the measurement and modeling of snow and ice melt (e.g., Marshall et al., C72B-05; Pelliccioti et al., C11A-0982). Sea ice and ice-ocean-atmosphere interactions represent another focus. One highlight will be new global simulations by Schmittner et al. (C11A-0975) that examine wind-driven sea ice motion and buoyancy fluxes in the Antarctic and Arctic, with implications for meridional overturning and ocean-atmosphere CFC exchange.

Education

ED61C, ED62A
Teaching the Teachers: What Have We (They) Learned? These sessions provide an opportunity to learn more about how evaluation of geoscience education projects is done and to learn how others have used evaluation to meet their project goals. This is of increasing importance as we seek to understand the successes and failures of our projects both for ourselves and for our stakeholders. Evaluation associated with projects ranging from informal education and student contributions to research missions to digital resource development, undergraduate courses, and the assessment of student misconceptions will be described. Those interested in this session are also encouraged to register for a free evaluation workshop to be held the evening of the session (http://cires.colorado.edu/~k12/agu).

ED71A
Faces of Diversity: Profiles of Women Geoscientists Posters As a female geoscientist, do you wonder if your professional path is unique or common? Are you wondering how to more effectively recruit female scientists to your institution? Combining background information on women in the geosciences and personal stories from women in the trenches, this session provides a venue to learn more about issues for women in geoscience. Invited and contributed posters include statistical information, employment trends, as well as stories from women in various stages of life in different geographic regions, ranging from two-career chaos to barriers and opportunities in academia, industry, government labs, and other agencies. This is the session to attend to find out about women's professional experience in geoscience.

ED71C, ED11A
Geophysics Data in the Classroom Programs that encourage students to make observations of the oceans, the atmosphere, or the solid Earth offer the opportunity to capture a student's innate curiosity for natural phenomena, and this curiosity can be used as a platform from which a wealth of fundamental principles of physics and Earth sciences can be taught. Successful examples of geophysical data use in the classroom will be presented by academic researchers, college faculty, and secondary and middle school teachers. The activities have been designed around data collected directly by students or accessed via the Internet and address a range of AGU disciplines including geodesy, meteorology, oceanography, seismology, and space sciences.

Geodesy

G61A
Slow Earthquakes in Subduction Zones Posters The last several years have witnessed a reappraisal of our understanding of the energy budgets of subduction zones. We now recognize that fault rupture commonly occurs over rates ranging from kilometers per second to millimeters per hour. Posters in this session describe and model episodic or periodic slow megathrust slip events that have been recorded along convergent margins in Japan, Alaska, Mexico, Cascadia, and Peru. This mode of slip constitutes a fundamental mode of strain release only observable through geodetic methods.

G61B, G62A
Geophysical Modeling Using Spaceborne InSAR Measurements Interferometric synthetic aperture radar (InSAR) methods provide centimeter-level geodetic observations at meter-scale resolution, characterizing deformation accurately at very fine spatial scales. Inverse modeling of these detailed data sets permits visualization of many processes at depth with an acuity not possible with sparser observations, and inverse geophysical methods, applied to InSAR data, are producing new insights into the processes that shape the Earth's surface and its environment. Major advances showcased here include the identification of new deformation sources in the Andes mountains, and the temporal analysis of deformation associated with two (coupled) M6+ earthquakes in Iceland. Study of ice flow in Antarctica is providing new insights into dynamics of the ice sheet and has significant implications for global warming and sea level rise.

G72A, G12B
New Results From the GRACE Mission GRACE was successfully launched on 17 March 2002. Following a 2-month commissioning phase, 6 months of science data for calibration and validation purposes were acquired to demonstrate the quality of the science data and tune the analysis algorithms for optimal performance. Already, GRACE has produced a significantly improved mean gravity field of the Earth. Monthly GRACE gravity fields are starting to provide information about temporal variations in the gravity field and their correlation with atmospheric, oceanographic, and hydrologic processes.

G11A, G12A
Geodesy at the Solid-Fluid Interface Global geophysical fluids have a major impact on the solid Earth. Changing atmospheric, oceanic, and hydrologic loads cause deformation of the solid Earth and displacement of geodetic observing stations. Global geophysical fluids cause the Earth's rotation to change by exchanging angular momentum with the solid Earth, accomplished through the action of torque applied both at the fluid-solid Earth interface and at a distance. The redistribution of mass by fluid flow causes the gravitational field of the Earth to change. Contributions discuss the impact of the atmosphere, oceans, hydrosphere, and core on site displacements, geocenter motion, and the Earth's rotation and gravitational field.

G21A, G22A
Continuous GPS Arrays: Results and Data Scrutiny During the 1990s, global and regional networks of continuously operating Global Positioning System (GPS) stations were built, making highly precise time series of station positions (and other parameters) available for investigation of a wide range of geophysical problems. Rich data sets are now available from which the real accuracy and precision of GPS can be assessed. Questions about what is the signal, and what is the noise, may be answered differently depending on whether one's interests are fault systems or aquifer systems. Presentations in this session evaluate noise levels, study tectonic and anthropogenic crustal deformation sources, and discuss applications of continuous GPS data.

Geomagnetism and Paleomagnetism

GP12C
Bullard Lecture: Plumes and Earth's Dynamic History: From Core to Biosphere We are pleased to have Vincent Courtillot presenting Geomagnetism and Paleomagnetism's inaugural Bullard Lecture. Vincent has always painted a colorful, sometimes controversial, picture of Earth's processes, and this lecture promises to be well within style. Plumes punctuate the decorum of plate tectonics with catastrophic eruptions of millions of cubic kilometers of igneous rocks. These events may well be responsible for mass extinctions and continental breakup, and can be correlated with the behavior of Earth's magnetic field, true polar wander, and large-scale mantle convection. Vincent presents the big picture, along with a bestiary of plumes sorted by depth of origin.

GP62A, GP71A
Stratigraphic Chronologies: Determination, Interpretation, and Quality Control Through a diverse group of participants, these sessions offer discourse on establishing, evaluating, and applying stratigraphic chronologies from sediment and ice cores. A wide range of methods are discussed, including astronomical tuning, layer counting and ice flow modeling, cosmogonic nuclides and constant flux proxies, and geomagnetic polarity. The applications of these methods are discussed in the context of climate change, atmospheric and ocean sciences, and paleomagnetism.

GP11A, GP12B
The Use of Magnetic Properties as a Petrologic Tool The properties of microscopic grains that carry the magnetic signature of a rock can reveal a wealth of information about the history of the rock and the environment in which it formed. In these sessions we see that careful rock magnetic and paleomagnetic analysis can be used to infer the erosional and climatic cycles extant during rock formation, and also deformation, or in the case of magmas, flow, during rock formation.

GP51A, GP52A
Electrical Conductivity and Physical Properties in the Lab and in the Earth These sessions, honoring the careers of Tom Shankland and Al Duba, focus on bringing together laboratory studies of rock and mineral properties and field studies of in situ electrical conductivity.

GP62B
Magnetic Database Developments: Public Forum The construction of databases of paleomagnetic and rock magnetic measurements promises to provide a rich resource for the creation and validation of geophysical models. However, the community needs to agree on data formats and even which data to submit, and then to devote considerable effort to getting previously collected data into archives. This panel discussion provides the opportunity for the Geomagnetism and Paleomagnetism community to discuss these issues. Geomagnetism and Paleomagnetism has coordinated the oral and poster sessions on databases with Ocean Sciences, and papers associated with this subject can be found in OS61C and OS62B.

GP61A
Numerical Modeling in Geomagnetism/Paleomagnetism Posters Predicting the behavior of magnetic domains in microscopic magnetic particles, and the magnetohydrodynamics of Earth's liquid iron core, are problems that differ in scale by 15 orders of magnitude, yet are amenable to similar numerical modeling techniques. In this session we see modern computational methods applied to a broad suite of problems in geomagnetism and paleomagnetism.

Global Climate Change

GC61A, GC62A, GC72A, GC72B
Carbon Cycle and Climate: Past, Present, and Future These sessions will address the carbon cycle as a component within the atmosphere-land-ocean system. These multidisciplinary sessions will be organized by timescales ranging from days to hundreds of millions of years. Specific topics will include the Phanerozoic carbon cycle, Pleistocene glacial-interglacial atmospheric CO2 changes, interannual to decadal carbon-cycle variations, and impacts of human activities on the carbon cycle and climate change.

Hydrology

H51A, H52E
Hydroclimatology of Large Northern Watersheds: From Observations to Modeling Current understanding of the hydroclimatology of large northern river basins is reviewed and synthesized. Emphasis is placed on the fundamental characteristics of large-scale hydroclimatological features through analyses of long-term observations and numerical model output, as well as to their variations and changes in space and time. Presentations are provided by the USGS (for the Yukon River), the Canadian GEWEX project (for the Mackenzie River), the Japanese GEWEX/Siberia program (for the Lena River), and the Pan-Arctic Community-Wide Hydrological Analysis and Monitoring Program (for the Pan-Arctic region).

H51C, H52C
Using Groundwater Models to Guide Field Data Collection Groundwater models can be powerful tools for guiding collection of data about the characteristics and state of the modeled system. The papers in these sessions illustrate the use of a broad range of groundwater flow and transport models to guide collection of diverse types of field data. Topics presented include the use of forward and inverse flow modeling to guide collection of hydrogeologic and recharge data for improved understanding of the flow system and of groundwater-surface water interactions, the use of transport models in conjunction with optimization techniques to design water quality monitoring networks, and the use of multiphase models to design NAPL field tracer tests.

H52A, H62F
State-of-the-Art in Ecohydrology Ecohydrological investigations have traditionally focused largely on vegetation interactions with the hydrologic cycle in water-limited environments. New insights on regional differences in ecohydrological patterns and processes emerging from studies of both plants and animals in a variety of environments are beginning to exert increasing influence on the field. A special feature is an introductory plenary presentation by Dr. Peter Eagleson (MIT) entitled "The Darwinian Expression of Vegetation Form and Function."

H52F, H61A
Advances in Information Fusion Technologies in Hydrological Sciences New methods for integrating geological, hydrological, geophysical, chemical, and biological data to enhance site characterization and monitoring are presented. The data integration methods described include approaches based on Bayesian, ensemble, and the successive linear estimator techniques, all of which enable uncertainty estimates. There are also contributions describing innovative and comprehensive uses of various data that should facilitate improved understanding and prediction of natural systems.

H61E, H62E
Twenty-Two Years of Stochastic Groundwater Hydrology The contributions of Allan Gutjahr to the field of stochastic groundwater hydrology are celebrated. A look ahead at the field's new directions, as well as back at the achievements realized by stochastic groundwater hydrology, are featured. Applications are drawn to well hydraulics, vadose zone hydrology, surface dynamics, hierarchical media, and solute transport.

H62A
Modeling and Observation of Precipitation Posters Precipitation variability in space and time has implications for topics ranging from weather and hydrologic prediction to the global energy budget. Presentations in this session describe observational studies using rain gauge data, the use of rain gauge data to derive precipitation fields for comparison with mesoscale model output, radar observations of microphysical phenomena needed to model rainfall (e.g., drop size distribution), and radar rainfall estimation.

H71A
Conceptual Model Evaluation and Quantification of Groundwater Model Error Posters Approaches to the difficult problem of identifying and quantifying errors in conceptual models of groundwater flow and transport are explored in this session. Presentations include philosophical discussions of appropriate model usage, descriptions of methodologies that incorporate elements of inverse modeling and/or Bayesian statistics, and case studies of specific sites and/or types of problems. The program includes two invited posters to be presented by Donald Sweetkind (U.S. Geological Survey) and Petros Gaganis (Foundation for Research and Technology-Hellas).

H11B, H12G
Incorporating Climate Variability in Water Resources Decision Making As understanding of climatic variability improves, opportunities are created for incorporating such understanding in decision making. Within water resources management, for example, opportunities exist to use improved knowledge of climate variability at intraseasonal, interannual, and interdecadal timescales. Presentations examine techniques for improving hydrologic predictions using climate information, procedures for using climate information to make better decisions (with examples ranging from agricultural policy to reservoir management), and assessments of the barriers to using climate information (which vary from a lack of understanding of the meaning and accuracy of climate forecasts to the issues facing decision makers when they consider using a new technology).

H11G, H12B
Climatic and Tectonic Controls on Hillslope Processes and Sediment Production Variations in sediment production at a variety of spatial and temporal scales, including theory-driven and field-based studies are explored. Range-scale studies in New Zealand, Taiwan, and Alaska are complemented by process-scale observations in soil-mantled and bedrock-dominated landscapes. The underlying theme focuses on the quantification and interpretation of variations in sediment production.

H12C
Nitrate in Groundwater: A New Look at an Old Problem Posters Nitrate is one of the most common groundwater contaminants in the United States, and its occurrence has been linked to a variety of health problems. Research reported in this session highlights the prevalence and remediation of nitrate in a variety of groundwater systems. Emphasis is placed on the importance of gaining a fundamental understanding of the associated microbial communities and processes at work in such environments.

H21C
Fluvial Geomorphology Posters An examination of river channels and the processes that carve them is provided in this session. A range of spatial and temporal scales is considered, including analyses of flow and sediment transport at the grain to the reach scale, as well as descriptions of the movement of sediment through entire watersheds and the development of channel networks. Experimental and field observations, numerical simulation and hydraulic modeling, studies of weathering and dating, and applications to reservoir sedimentation, stream profile development, and channel restoration are included.

H21D, H22F
Uncertainty in Vadose Zone Flow and Transport Prediction Little attention has been paid to the degree of uncertainty present in models that predict flow and transport in the vadose zone, which is the primary natural barrier to groundwater contamination. The sources of such model uncertainty, including the basic conceptual model, the character of the geologic media, the number of modeled phases, boundary and initial conditions, property measurements, model implementation, and the type of decision driving the modeling (deterministic versus stochastic), are addressed.

H22B
Hillslope and Basin Geomorphology Posters Hillslopes play a significant role in drainage basin evolution. Field- and model-based reconstructions of landscape history from landform interpretations are highlighted in this session. Consideration is given to the role of weathering in the alteration of Earth surface materials and to the problem of quantifying sediment mobility on hillslopes. The use of remotely sensed data for quantifying topography and identifying processes is also explored.

Nonlinear Geophysics

Nonlinear geophysics is AGU's umbrella term that includes the fields of chaos, nonlinear dynamics, complexity, fractals, multifractals, and self-organized criticality. Each of these fields brings a new approach to the analysis, interpretation, and modeling of geophysical systems. Advances include new and deeper levels of quantitative understanding of nonlinear systems. Oral and poster sessions will be spread out over the week, with themes of broad interest to the nonlinear geophysics and AGU community.

NG52A
Scaling, Predictability, and Earthquake Fault Models This session presents new insights into earthquake scaling, predictability, and fault models by investigators who apply nonlinear approaches to study earthquake sequences. This session includes papers that develop new ideas regarding the physics of earthquakes and related computational models. Researchers present evidence that earthquakes occur in hierarchical correlated clusters that reflect the fractal nature of faults and stick-and-slip dynamics within the Earth's crust.

NG52B
The Lorenz Lecture Series: Donald Turcotte The annual Lorenz Lecture, sponsored by the AGU Nonlinear Geophysics Focus Group, will be delivered by Donald L. Turcotte of Cornell University. Among his many accomplishments, Professor Turcotte is the author of the book Fractals and Chaos in Geology and Geophysics. Professor Turcotte has a gift for making this subject readily accessible to the Earth science community. His lecture is entitled "Self-Organized Complexity in Geophysics."

NG61A, NG12A
Visual Computing in Nonlinear Geophysical Phenomena Geoscientists, especially those concerned with nonlinear dynamical phenomena, are increasingly overwhelmed by a deluge of data generated by modern acquisition experimental facilities and high-resolution numerical simulations. These sessions feature modern analytical and visualization tools that treat and analyze large datasets. Applications include global dynamical models of the Earth's mantle and lithosphere, wavelet analyses of geophysical systems, geodynamo models, earthquake simulations, rock fracture, granular flow, and global ocean velocity, temperature, salinity, and surface conditions. Commercially available software makes visualization of nonlinear systems accessible to the wider geophysics community. Session NG61A will be held in the visualization theater located in Hall C.

NG71A, NG72A
Scaling and the Fluid Earth: Chaos and Multifractals in the Atmosphere, Oceans, Hydrology, and Climate The ubiquity and fundamental importance of scaling has been increasingly recognized in geophysics. These sessions are devoted to the latest development of scaling concepts, models, and analyses, from fractal structures to extreme multifractal variability and scaling nonlinear dynamics. Highlights include papers on stratified multifractal atmospheric turbulence and on chaos versus stochasticity and the resulting predictability issues in the atmosphere, oceans, hydrology, and climate.

NG11A, NG11B, NG22A, NG22B
Recent Advances in Nonlinear Geophysics These sessions, focused on recent advances in nonlinear geophysics, include nonlinear geophysical research on model testing and validation in the geosciences, natural and human-induced hazards, nonlinear physical properties of geophysical materials, nonlinear waves and solitons, hydrology and geophysical transport processes, and damage rheology and the physics of earthquakes.

Ocean Sciences

OS51A
Prediction of Underwater Landslide Hazards Posters This session covers a set of multidisciplinary/interdisciplinary papers on all aspects of submarine landslides and focuses on new research directions that may ultimately lead to improved prediction tools. Papers include regional overviews of landslide hazards on both continental and convergent margins, as well as local case studies of areas ranging from North America to Papua New Guinea and Norway. Themes include quantitative landslide simulations, engineering characteristics of slides, relationships between slides and seismicity, and observational studies using sophisticated marine surveying technologies.

OS51B
EOS Data Access and Manipulation: Tools and Techniques Posters This session describes tools to find, access, and manipulate data from various Earth Observing System (EOS) missions. It informs scientists, data producers, planners, and managers of available data systems, services, tools, and standards for managing and manipulating EOS data. Many of the posters will be supported by computer access for on-site demonstrations.

OS51D, OS52C
Quantitative Developments in Coastal Oceanography Our understanding of coastal currents and water properties has evolved since the early 1970s to a state where we now have quantitative understanding of many phenomena. In some cases, we are developing predictive capabilities. Much of this progress was led or exemplified by Dr. John S. Allen. These session include a few reviews of progress over the last 30 years and many presentations that point to new advances in shelf and surf zone oceanography.

OS52F, OS71B
Coastal Geology of the Carolinas: Linking the Shelf and Shore Recent research on inner continental shelves suggests that the shallow geologic framework exerts a primary influence on coastal evolution at timescales from storm events to millennia. These sessions will highlight interdisciplinary investigations of the Carolinas coastal zone that seek to understand the relationships between physical oceanographic processes, sediment distribution and transport pathways, coastal evolution, and the geologic framework. Interpretations of data from seafloor and subaerial mapping studies, ground-penetrating radar surveys, core holes, and observations of physical processes will be featured.

OS61B
Scientific Advances From Stable Offshore Platforms Posters This session reviews the various large spar buoy research platforms that have been used in the past and are visualized for the future for DEOS and other more general applications. Primary emphasis, however, is on research accomplished in the last 40 years using FLIP, the most durable and versatile of spar buoy laboratories. Research contributions include studies of air/sea interaction, internal waves and turbulence, Langmuir cell physics and associated zoological effects, underwater acoustics, optical and radar transmission from the sea surface, and biogeochemical and bio-optical processes. In all of these topics the concern is both with significant contributions already made and with opportunities for future research.

OS61D, OS62A
Wind-Driven Processes Along the U.S. West Coast Continental Shelf Along eastern boundaries, wind-driven upwelling has major impacts on the ecosystem and cross-shelf transport These sessions look at processes and responses representing physical, chemical, and biological variability in these wind-driven systems.

OS71D
The Yin and Yang of Quaternary Climatic and Sea Level Fluctuations During the Past Two MA and How Does This Bear Upon Predictions for Future Climatic and Sea Level Changes? Posters Postglacial sea level rise of the last 15,000 years has occurred in a stepwise fashion, with steps caused by glacial meltwater pulses, up to 20 m in amplitude. Papers in this session bear on this history in addition to longer timescale events in sea level history and how shorelines have responded to it. Presentations include observations of past shoreline indicators, relative sealevel in the historical record, causes of the blips seen in sealevel history, and models that incorporate the many factors that must be input in order to simulate the physical geology left behind in coastal regions.

OS71F, OS72B
Scientific Results From Coastal Ocean Observing Systems New scientific results on coastal ocean circulation and related processes, made possible only by establishing multiyear time series from spatial networks of various sensors, are described from virtually every region of the United States. Particularly noteworthy are the syntheses of results from sensors sampling a variety of variables, the use of numerical models together with the relatively and inevitably sparse observational data to make full field estimates, and the integration of ecological and physical observations and analyses. A take home message: Full water column observations as well as relatively dense and comprehensive surface observations are important. Hence many of the necessary ingredients for an integrated and sustained coastal ocean observing system are displayed from a 'bottom-up" perspective.

OS11F
Sverdrup Lecture A number of substances have been released into the environment on a global scale from humankind's activities. Observation of the passage of these tracers into and through the oceans is providing us with a remarkable opportunity to examine the rates, pathways, and mechanics by which material fluxes occur. Such information is critical to our understanding of how the ocean participates in the grand biogeochemical cycles, the Earth system, and long-term climate regulation. This understanding is important for forecasting and possibly ameliorating natural and anthropogenic global change.

OS12D, OS21C, OS22A
Ocean-Atmosphere Interaction and Climate Variability These sessions focus on climate variability associated with ocean-atmosphere interaction in the Pacific and Atlantic, including the climate phenomena of the El Nino-Southern Oscillation, the tropical Atlantic meridional gradient mode, the Atlantic Nino, and the North Atlantic Oscillation.

OS21D, OS22B
Dynamic Processes Governing Estuaries These sessions present past and recent sedimentation processes and their variations, the distribution of contaminants, and measurements and modeling of hydrodynamic processes in estuaries.

Paleoceanography and Paleoclimatology

PP51B, PP52A
Interpreting Climate Change From Isotopic Records of Precipitation The stable isotope composition of meteoric water, as recorded in continental archives such as glacier ice, lake sediments, groundwater, speleothems, and organic matter, has become an indispensable tool in studies of past climate and hydrological conditions. These sessions highlight exciting new advances in the science of interpreting these paleoprecipitation records. Papers will present recent improvement of the global database of isotopic composition in modern precipitation, analytical developments in the collection of isotope proxies of past precipitation and high-resolution data sets, innovative calibration studies to better understand how isotope proxy data in continental archives are derived from initial precipitation events, and significant advancements in incorporating water isotope tracers into atmospheric global climate models.

PP61B, PP62A
Past Changes of the Hydrological Cycle in the Tropics and Subtropics Little is known about the long-term variability of the hydrological cycle, a subject of great concern for society. These sessions will present results from the paleoclimatic record that address past variability of the hydrologic cycle in the tropics and subtropics. Records from both marine and terrestrial settings and spanning a wide range of timescales will be presented, as will papers that discuss theory and modeling as a means of understanding internal variability of the hydrological cycle and its sensitivity to external forcing.

PP62C
Cesare Emiliani Lecture This annual lecture series was created by the AGU Committee on Paleoceanography and Paleoclimatology to honor the memory of Cesare Emiliani and to recognize individuals who have made outstanding scientific contributions to our understanding of past oceans and climates. Richard B. Alley of The Pennsylvania State University will give this year's Cesare Emiliani lecture. Alley's presentation, entitled "'Prepare Immediately for Whatever Is Going to Happen Next': A Paleoclimatic View of the Future," will highlight natural variability of the Earth's climate as shown by paleoclimatic data, ranging from interannual shifts through decadal-centennial droughts to millennial abrupt jumps, that have often been larger than documented by the short instrumental record.

PP71C, PP72A
The Climate Record of the Last Two Millennia An accurate and quantitative reconstruction of the climate history of the past 2 millennia has the potential to provide important insight about the uniqueness of the late twentieth century warming and the extent to which it is attributable to anthropogenic forcing. These sessions bring together researchers from a range of disciplines, each working to reconstruct parts of the Earth's climate history of the past 2 millennia. We anticipate a lively exchange of ideas and new results that will form the basis of discussions about climate variability through the ages.

Planetary Sciences

P51A
Martian Dust Devils: Observations, Simulations, and Terrestrial Analogues Posters The latest MOC observations of devils and tracks and in situ measurements of terrestrial dust devils provide the empirical data in this session. These data are developed in numerical mesoscale convection models and laboratory simulations of both threshold and electrical structure. Electrical structure is explored in both laboratory simulation and field data, and comparison between the two will provide an interesting highlight of this session.

P51B
Mystery of the Martian Rivers Posters There is a preponderance of geomorphic evidence suggesting liquid water once flowed on the surface of Mars. The most popular paradigm is an early Mars climate that was warmer, wetter, and stable. Yet climate models to date have not been able to produce a continuously warm and wet early Mars. This session debates old and new ideas to explain the mystery of the Martian rivers. Many of the new ideas suggest a far different early history for Mars, which is far less hospitable to life or its origin.

P51C, P61B
Fundamental Discoveries in Planetary Science: The Color of Worlds The Planetary Sciences Whipple Lecture entitled "Remote Compositional Analysis: The Coming of Age" is presented by Whipple Award recipient Thomas B. McCord. The Whipple Lecture (P51C) will be followed by a special session dedicated to the great diversity of accomplishments and ongoing discoveries achieved through spectroscopic applications of remote compositional analyses over the last 30 years. Several overview summaries as well as examples of focused research are presented for Mercury, the Moon, Earth, Mars, asteroids, and icy satellites.

P52A
Deciphering Mars's Paleoclimate: Observations and Models Posters This session jointly examines how remote sensing and modeling illuminate Mars's climate history. Recent Mars orbiters have observed paleolakes and enigmatic polar landforms. Meanwhile, modelers attempt to understand how orbital variations influence the bulk atmosphere, dust and volatile cycles, and surface processes. Bringing together both types of research helps achieve the ultimate goal: a quantitative understanding of Mars's paleoclimate.

P52B, P71C
Stable Isotopes and the Search for Life in the Solar System These sessions will explore how the stable isotopes of carbon, oxygen, sulfur, and iron can be used to find evidence of life in the solar system. Papers ranging from carbon isotope compositions of ice on Mars to using Fe isotopes as a probe for bacteria in the Antarctic Dry Valleys will be presented. The use of compound specific carbon isotopes and mass-independent sulfur isotopes in Archean rocks as an analogue for Mars will be discussed. The phosphate oxygen isotope biomarker with applications to Mars and the oxygen isotope composition of water on early Mars will also be heard.

P52C, P61A
Space Weathering of Solid Surfaces in the Solar System and Elsewhere These sessions focus on the fundamental chemical and physical mechanisms of space weathering in ice and nonice surfaces and on the resulting optical effects of these alterations. Many results from the irradiation of ice and nonice materials in the laboratory will be presented. Observations from the Hubble Space Telescope and the Galileo mission, as well as theoretical modeling of the optical, as well as chemical and physical, effects of space weathering, will be presented. The discussions are relevant to the surfaces of Mercury, the Moon, the asteroids, and the outer icy satellites.

P61C, P62A, P71B, P21B
Our Evolving View of the Geology of Mars The Mars Odyssey joined the Mars Global Surveyor in Mars orbit earlier this year, and the data they provide are changing our understanding of the geology and geophysics of our neighboring planet. These sessions present work on these data and make plans for future missions.

P61D, P71A
Terrestrial Analogues for Planetary Studies Since close examination of extraterrestrial surfaces is currently extremely difficult, interpretations of the characteristics and features of other planetary objects often use terrestrial analogues as a reference. The most successful comparisons have focused on understanding processes on the Earth well enough to extrapolate them to other terrestrial planets and satellites. These sessions will examine geological and geophysical studies of volcanic, hydrologic, hydrothermal, lacustrine, glacial, and spectral terrestrial analogues and their applications to planetary studies.

P62B, P72A
Closing the Loop: Remote Analysis of Terrestrial and Planetary Surfaces These sessions bring together researchers working at the interfaces between laboratory, field, and satellite remote sensing linked through theoretical models. All scales of remotely sensed data will be presented and analyzed, with contributions from terrestrial and planetary researchers. These sessions are designed for cross collaboration among researchers working in these complimentary but often nonoverlapping fields.

P72B, P12C, P21B
Outer Planet Satellites Recent spacecraft data, experiments, and theoretical advances are combining to greatly improve our understanding of the interiors of outer planet satellites and how their evolutions affect the fascinating surfaces we see. These sessions focus on new formation models for the satellites of Jupiter and Saturn that hold the promise of resolving long-standing issues, experiments, and theory on how satellite interiors react chemically to pressure and increasing temperature and how they respond physically over geologic time. Papers will address the formation of oceans, ultrahigh-temperature volcanism and mountain building on Io, icy convection on Europa and elsewhere, and predictions for Titan. Results from the final satellite encounter of the Galileo mission, with Amalthea, will also be presented.

P72C, P12A
Extant Water on Mars: Its Abundance, Physical State, and Role in Modern Geologic Processes These sessions include a summation of our current understanding of water on present-day Mars and exciting new findings. The discovery of significant amounts of frozen water in the south polar region is presented. Overview talks on this subject, plus water ice, gullies, and the atmosphere, are included. Contributed talks and posters cover recent studies of ground ice, gullies, the role of water in forming slope streaks, atmospheric water transport, and future mission plans.

P11B, P12B
New Results From Mars Odyssey These sessions will report on the first results from the radiation detector aboard the spacecraft, new analyses of the highest-resolution multispectral images of Mars, and new estimates on the amount and distribution of water in the Mars regolith. Come see the unfolding story of the compositional history of the Mars surface.

P21A, P22D
Advances in Planetary Geodesy, Mapping, and Imaging Planetary exploration has progressed from a time of initial reconnaissance of the solar system using mostly planetary flyby missions and exclusively images from framing cameras, to much more extensive missions of targeted exploration using orbiting spacecraft, line-scanner cameras, laser altimeters, and other sensors. These sessions commemorate the work of Merton E. Davies (1917-2001) by covering the early history of planetary mapping, recent advances in this area, the current state of the art, and planned future missions.

P21C, P22A
Mars Exploration Rover Mission: Setting Down on the Red Planet Once Again These sessions are devoted to the Mars Exploration Rover mission, a dual-rover mission scheduled to launch in mid-2003 and land on Mars in January 2004, and provide an overview of the mission and the selection and characterization of candidate landing sites. Plans for science investigations, calibration, and data archive and release are described. Results and lessons learned from remote robotic geology tests using a similar rover called FIDO are also included.

Seismology

S51A, S52C
Seismic Discontinuities, Phase Transitions, and Mantle Dynamics These sessions present observational and experimental data on seismic discontinuities in the mantle. The goal is to better understand the underlying processes and conditions of the mineral phase transitions and mantle dynamics. Highlights include seismic observations pertaining to cratonic roots and possible reflectors (in some cases, multiple reflectors) in subduction zones and the lower mantle. Experimental data from mineral physics involving pyroxenes, high-pressure silica polymorphs, and postspinel transition will be presented. These sessions also provide a forum to review the merits and limitations of existing observations associated with mantle discontinuities.

S51C, S61B, S71A, S22C
New Advances in the "Software" and "Hardware" of Seismology These sessions feature a variety of new ideas and techniques in the theory and practice of seismic waveform observation and modeling. One leading edge of computational seismology involves the utilization of massively parallel computer processing hardware. Other advances involve innovative simulations of scattered wave energy. In addition, seismometer technology is increasing our ability to measure ground motion in formally inaccessible area (e.g., the seafloor), acquire torrents of data from ever-widening and ever-densifying networks of seismic sensors, and deliver seismic data in user-friendly format to facilitate earthquake hazard mitigation, nuclear explosion monitoring, and studies of subsurface Earth structure.

S51D, S52B, S61E, S71B, S71C, S72D, S72E, S12B
Earthquake Process and Hazard Sessions The "earthquake problem" continues to be one of the most important and intriguing unsolved puzzle of geophysics. In a series of sessions, contributed presentations will present new research results on stress-triggering of aftershocks and main shocks, nonlinear velocity-slip models for earthquake recurrence, notable recent earthquake behavior, and a host of related topics. In addition, at the Seismology/Tectonophysics Luncheon on Saturday (tickets required), the distinguished seismologist Thomas Jordon of the University of Southern California will summarize the findings of the recent National Research Council report on the science of earthquakes. Practical applications of our improved understanding of earthquake processes will directly benefit seismic hazard mitigation. Several of these sessions feature talks and posters that address the application of geophysical insight to the characterization of damaging strong motion and forecasting future earthquake hazards.

S61A, S62D
Lithospheric Structure in North America and Europe: Comparisons and Recent Results These sessions offer about 40 oral presentations and posters featuring seismic studies of lithospheric structure in the Europe and North America regions. This provides an opportunity to compare recent results from a number of large cooperative experiments and from tectonic settings that range from cratons to orogenic belts to active rifts. The results of a wide variety of seismic techniques are also presented that should provide insight through comparisons.

S61D, S62B
Young Continent-Continent Collisions These sessions focus on seismological investigations of actively deforming continental convergent plate boundaries. Scientists working on problems related to active continental collision will present and discuss the most recent images and models for the collision and suturing of continental plates. Recently, there have been a number of important recent seismological studies in young continental collisional belts including eastern Turkey, the Zagros mountains, and New Guinea. Data from recent PASSCAL experiments (in eastern Turkey and New Guinea) and from recently installed permanent networks (in Iran) are being used to construct exciting new images of the crust and upper mantle in these regions. However, it is also very important to integrate the seismic results with geodynamic modeling, geochemistry of collision related basalts, seismotectonics of young plateaus, and geology of continent-continent orogens. There is a sad footnote to this session. K. Douglas Nelson, Department Chair and Jessie Page Heroy Professor of Earth Sciences at Syracuse University, died suddenly of heart failure on 17 August 2002, at age 49. At the time of his death he was at the height of an increasingly distinguished career, and had, just prior to his death, agreed to be an invited speaker in this session of the 2002 AGU Fall Meeting. The oral session will begin with a tribute to Professor Nelson, delivered by Simon Klemperer.

S62C
Tonga Deep Earthquakes, 19 August 2002 Posters On 19 August 2002, Mw=7.6 and Mw=7.7 deep earthquakes occurred within 8 minutes of each other in the Tonga subduction zone. The largest of these represents the largest deep earthquake in the past 6 years and may be the largest deep earthquake ever recorded from the Tonga subduction zone. Furthermore, the close association of the two events in time provides evidence for earthquake triggering at considerable distances in the transition zone. This session will explore the tectonic setting, source characteristics, and implications of these events for our understanding of deep earthquakes.

S71E, S72B
Radiated Energy and Apparent Stress: Constant or Nonconstant Scaling? The estimation of radiated seismic energy (Es) remains an elusive seismological parameter. Reliable and believable estimates of Es must integrate over the entire source spectrum and include proper corrections for frequency-dependent path and site effects as well as source radiation pattern and directivity. In contrast, the measurement of seismic moment (Mo) has become increasingly robust for smaller and smaller events as regional broadband networks expand. If measured properly, the apparent stress (~Es/Mo) can provide a convenient macroscopic view of the dynamics of the earthquake rupture. With the advent of broadband seismometers and increased station distribution there has been a renewed interest in Es over the past decade. New methods have been employed to estimate Es, and despite this renewed interest there is currently no consensus on whether or not the apparent stress is constant as a function of earthquake size. This has important hazard implications because nonconstant stress-drop scaling could impact ground motion prediction estimates for the future large-magnitude earthquake. On a more basic level, the estimation of Es can constrain earthquake rupture models and rheology. In addition to the scaling debate, there are large discrepancies between teleseismic estimates of energy as compared to local and regional estimates for the same events that need to be resolved.

S72C, S11A
Plumes, Hot Spots, and Calderas These international sessions focus on the existence, origin, and composition of these features that have been advanced by new seismic imaging experiments. Seismic data along with constraints from new GPS measurements, helium geochemistry, etc., provide key information on dynamic models of lithosphere-asthenosphere interaction. All of the papers address in some way the key question: Are hot spots driven by deep mantle plumes or not? Contrasting interpretations highlight the differences in models and data and point out the limiting resolution of our ability to resolve such deep Earth processes. Fifty-seven presentations on such features ranging from the Hawaii, Galapagos, Yellowstone, Iceland, Eiffel, Afar, Reunion, etc., hot spots to the Yellowstone, Long Valley, and Campi Fleigri calderas will be given by scientists from around the world.

S11B, S12C
Historic Earthquakes Presentations will focus on the investigation of important earthquakes for which we have no recorded (seismic) data, as well as the scientific and historical issues associated with research on historic earthquakes. Talks will focus on such topics as a closer look at the 1857 Fort Tejon, California, earthquake, past and possible future great earthquakes in India, the importance of historic earthquakes to better understand seismic hazard in Europe, and the investigation of historic subduction zone earthquakes in Japan. Several presentations will also discuss historic earthquakes as a unique and valuable data set with which one can investigate such general issues as the long-term behavior of fault systems and strong motion site response.

S11D, S12A
Forensic Seismology: Exotic Seismic Sources and Man-Made Events The large number of seismic stations deployed globally to monitor earthquakes or underground testing of nuclear weapons also record an extraordinary variety of other natural and man-made phenomena. Examples include chemical explosions (accidental, industrial, and terrorist), bolides, cultural noise, volcanic eruptions, storms, landslides, and iceberg movement. Seismic analyses of such exotic sources can provide information that is useful to investigative agencies, insurance companies, and governmental organizations, and the results are often scientifically interesting in their own right. These sessions feature presentations on (1) results of exotic source modeling and (2) implications of exotic source study for public education and outreach. Contributions based on hydroacoustic and infrasonic data are featured as well.

S12E
Gutenberg Lecture In his talk entitled "Bananas, Doughnuts and Seismic Traveltimes," the distinguished seismologist F. Anthony Dahlen will address an emerging paradigm shift in the practice of seismic tomography. Exploiting parallel developments in ray theory and free oscillation theory, seismologists are beginning to discover the fine structure of the resolution kernels of seismic tomography. These kernels reveal some surprising geometries that can be motivated intuitively and caution against the overinterpretation of some types of seismic data. Seismic tomography is used to generate three-dimensional maps of seismic wave speed variations in the subsurface Earth, and these images are key to the thinking of other geophysists in the study of our planet's geologic structure and dynamics.

S21B, S22D
Seismicity in Stable Continental Region (SCR): A New Look Inspired by Recent Earthquakes in Eastern North America and Other SCRs Papers dealing with recent damaging earthquakes in Adirondacks, New York, and Wabash Valley fault zone, Indiana, as well as Bhuji, India, will be presented. Over 25 authors dissect most of the well-known SCRs using GPS, regional wave propagation, tomographic analysis, and other tools, from New Madrid seismic zone, central United States, China, Brazil and to Indian subcontinent. High-quality data from broadband seismographic stations deployed in eastern North America and in Europe in recent years start to yield important new results on ground motion attenuation, accurate focal depth, and source mechanisms of moderate-sized earthquakes using the regional moment tensor inversion method.

S21C, S22B
New Views of Seismic Hazards in Cascadia Presentations will summarize many aspects of earthquake hazard assessment in Cascadia including observations of recent aseismic slip events on the Cascadia megathrust, the evidence for widespread serpentinization of the forearc upper mantle, the temporal variability of the recurrence of large Cascadia subduction earthquakes, and seismic and geodetic observations of the Nisqually earthquake. In addition, new insights on the structure and paleoseismology of crustal earthquakes near Seattle and Portland will be presented. Finally, presentations will summarize new insight into the seismic hazards in Alaska as evidenced by crustal and Benioff zone seismicity.

Space Physics and Aeronomy

SA11A, SH11B, SM11A
Nicolet Lecture During the last century, there has been continual progress with regard to elucidating the important aeronomic processes that operate in the Earth's upper atmosphere. At the beginning of the new millennium, aeronomy is at the threshold of another rapid advance in knowledge due to the use of data assimilation techniques. During the coming decade, tens of millions of measurements of the ionosphere-thermosphere system will become available on a daily basis from a myriad of in situ and remote sensing instruments. These data sets can be assimilated into time-dependent, physics-based, numerical models of the ionosphere-thermosphere system, making it possible to provide continuous time-dependent three-dimensional reconstructions of ion and neutral densities. Professor Robert Schunk of Utah State University will address this subject in an honorary lecture entitled "Aeronomy: From Exploration to Data Assimilation."

SPA: Aeronomy

SA61A, SA62B
Scientific Results From the TIMED Mission The NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite has been measuring atmospheric structure and energy balance between 60 and 180 km altitude since its launch on 7 December 2001. It will provide at least 2 years of continuous, global observations of important geophysical parameters using four remote sensing instruments: a far ultraviolet spectrograph, an infrared radiometer, a Fabry-Perot interferometer, and a solar extreme-ultraviolet spectrometer. Results from these experiments and from related ground-based observations are presented.

SA11B, SA12A, SA21B
Tracing the Sun-Earth Connection Into the Upper Atmosphere: Study of the April 2002 Events During 14-24 April 2002, a series of solar coronal mass ejections and flares caused extreme perturbations to the solar wind, magnetosphere, ionosphere, and upper atmosphere. This period is ideal for study of the response of the geospace system to solar events because of the range of geophysical phenomena that occurred and the availability of measurements with which to explore and characterize them. Papers combining data across traditional science disciplines address important systems aspects of the April storms.

SPA: Solar and Heliospheric Physics

SH51A, SH52C
Toward an Integrated Solar-Terrestrial Data Environment Progress during the next era of solar-terrestrial science will require an increasingly integrated data environment, one that offers easy and simultaneous access to multisource high-quality observations, model output, and data services that span traditional discipline boundaries. These sessions highlight achievements and lessons learned from current systems and services, address the scientific, technical, and programmatic data challenges that face the space science community, and describe emerging architectural and technical solutions.

SH51B, SH52B, SH72A
Particle Populations Upstream of the Earth's Bow Shock: Observations, Theory, and Simulations The origin of the ion populations upstream of the Earth's bow remains controversial despite several decades of intensive research. Besides the evident importance to our understanding of bow shock physics, an improved understanding of upstream ion populations will contribute significantly to our understanding of shock acceleration processes and magnetospheric organization at all the magnetized planets. Specifically, the relative contribution to the upstream ion population by magnetospheric energization and outflow compared to particle acceleration at the bow shock is unclear. Furthermore, the particular mechanism for shock acceleration, possibly shock drift or first-order Fermi acceleration, remains controversial. Recent multispacecraft and compositional observations have fueled major progress in this field and are reshaping and providing the impetus for important advances in theory and simulations. These sessions have attracted a wide range of papers, and recent key observations will test earlier models, something that promises for controversial discussions.

SH61A, SH62A
Particle Acceleration at Inner Heliospheric Shocks: Observations, Theory, and Modeling Solar energetic particle (SEP) events are often associated with heliospheric shocks, often driven by coronal mass ejections. Understanding the temporal characteristics, the observed spectra, and the composition of SEP events has been an outstanding and controversial problem in space physics. That SEPs can sometimes serve as a precursor signal for the incipient arrival of large shock waves at the Earth makes them a possibly important tool for space weather forecasting, provided a better understanding of their acceleration and propagation characteristics is achieved. The large amount of observational data returned by spacecraft such as ACE and WIND, for example, offers great opportunities to develop and test theoretical models and simulations. The interpretation of often complicated data sets by sophisticated models will be the focus of these sessions.

SH71A, SH72B, SH11A
Energetic Particle Transport in the Heliosphere These sessions will discuss the theory and observations of galactic cosmic rays, anomalous cosmic rays, pickup ions, and solar energetic particles, concentrating on their transport throughout the heliospheric solar wind. Since energetic charged particles are governed by streaming and pitch angle scattering along the interplanetary magnetic field, these sessions focus on their microscale interaction with low-frequency MHD waves and turbulence. Although a microscale process, the effects of scattering influences particle propagation, transport, and acceleration on the largest scales. The presentations will contrast the role of two-dimensional MHD turbulence and isotropic and slab MHD turbulence, and the role of incompressible versus compressible MHD fluctuations, and will explore the entrance of energetic galactic particles into the heliosphere.

SPA: Magnetospheric Physics

SM51C, SM61A, SM21C
Magnetic Reconnection in Collisionless Plasmas: Theory and Observations These sessions provide a forum for the comparison of magnetospheric satellite observations and laboratory experimental results with theoretical models of collisionless reconnection. This cross comparison of results will focus primarily on the microscopic signatures of collisionless reconnection: the Hall quadrupolar magnetic field, electron beams, turbulence, electron hole formation and anomalous resistivity. In addition, some macroscopic features of reconnection such as flux transfer events and energetic ion signatures in the ionosphere will be examined.

SM52A, SM61B
ULF Waves and Their Role in Diagnosing the Plasmasphere Recent advances in deriving magnetospheric plasma density from the observations of ULF waves (from 1 mHz to 1 Hz) have attracted much attention to using ULF waves to determine the state of the plasmasphere, as well as to the influences of the plasmasphere on the characteristics of ULF waves. These sessions include papers that present the latest progress in understanding the behaviors of ULF waves, new observations of the plasmasphere collected by ongoing satellite missions, and techniques of ULF/VLF wave diagnostics.

SM52B, SM71A
Substorms and Storms Dr. Emil L. Kepko is the 2002 recipient of the Space Physics and Aeronomy section F. L. Scarf Award. His paper on "Transient Convection in the Earth's Magnetosphere and the Generation of Pi2 Pulsations" is the lead-off paper for session SM52B. In addition to Dr. Kepko's paper, many aspects of substorms and storms will be presented, including models of substorm initiation, the role of triggering in substorms, and multispacecraft observations of substorm and storm phenomena.

SM62A, SM12B
Discontinuous Cusp and Magnetospheric Boundary Layers These sessions present reviews and new results on the spatial and temporal effects in the discontinuous cusps and boundary layers. The discontinuous or staircase cusp has long been associated with the varying solar wind and IMF conditions. However, recently a number of observational and modeling works show that the discontinuous cusp can also be a spatial feature occurring under steady solar wind and IMF conditions. These sessions seek to find common principles in this phenomenon, which should have implications to merging theories.

SM62B, SM22A
Coupling of the Subauroral Ionosphere, Plasmasphere, and Magnetosphere Until recently, events observed in the ionosphere equatorward of the auroral zones were considered to be the fringe effects of events in the auroral zones. Recent observations have shown that penetration of electric fields to subauroral latitudes and the inner magnetosphere has a number of space weather and geophysical effects. These electric fields have been shown to exist during storm, substorm, and mildly disturbed periods. Various theories exist that attempt to explain these inner magnetospheric and low-latitude electric fields. These sessions discuss our current understanding of the causes and effects of these low-latitude and inner magnetosphere electric fields.

SM71B, SM72C, SM12A
Magnetosphere-Ionosphere Coupling Magnetosphere-ionosphere coupling studies the mass, energy, and momentum transfer between plasmas of different parameter regimes each with distinct dominant physical processes. The electromagnetic field, currents, and particles respond differently to changes in each side of the coupled system. Local phenomena may be a result of global processes, and local processes can lead to global consequences. Recent observations from both spaceborne and ground-based instruments have provided vast information about the coupling processes, especially multipoint simultaneous observations at both large and small separations. In addition, more sophisticated global simulation models have been developed to describe the processes in a more realistic manner. Theoretical investigations are also under way to bridge the gaps existing between the conventional magnetospheric and ionospheric approaches. These sessions present the latest theoretical, numerical, and observational results related to this coupling and discuss and debate the physical understanding thus obtained.

SM72B, SM22B
Dipole Tilt Effects on Sun-Earth Connections The 23.5 degree offset between the Earth's rotation axis together with the 11.5 degree tilt of the magnetic dipole with respect to the rotation axis introduces a significant semiannual variation in geomagnetic activity. The dipole tilt affects the efficiency of magnetic merging at the magnetopause as well as the shape of the magnetospheric obstacle. Differences in solar illumination result in hemispherical differences in ionospheric conductivity, which in turn affect the coupling with the magnetosphere and solar wind. Investigations of dipole tilt effects have the potential to resolve long-standing questions about the relative roles of ionospheric conductivity and solar wind drivers in modifying and controlling magnetospheric activity. These sessions present both a historical perspective of dipole tilt effects as well as many new results that take advantage of improved modeling tools, new data sets, and sophisticated statistical approaches.

Tectonophysics

T51A, T52D, T61A, T71A, T71B, T72B, T11D, T12E, T12F
New Views on Continental Lithosphere and Continental Dynamics This year's AGU Fall Meeting will push back the boundaries of continental dynamics by focusing on the continent-atmosphere interface and on the continent-mantle interface. The dynamic interaction of surface process with continental tectonics will be the focus in two special sessions. These sessions will highlight the recognition that geomorphologic and tectonic processes must be addressed as a coupled system if we are to truly understand the evolution and dynamics of continents. Another session will apply this theme to the boundary between continents and the mantle, as it will focus on the coupling between mantle dynamics and continental tectonics. Not only will discipline boundaries be pushed back but so also will the boundaries of long-held ideas about the continental lithosphere itself. A session will bring together new data and theory, from a range of fields, that is challenging old as well as established paradigms on the deep lithosphere of continents. The number of sessions devoted to continental tectonics/dynamics and to the structure of the continental lithosphere will provide a view of continents from their surface to their base. In particular, this year's AGU Fall Meeting will focus on the processes that occur at the dynamics interfaces that define the top and the bottom of the Earth's continents.

T51E, T52B, T52E, T52F, T11A, T11B
Seafloor Hydrogeology Water circulation into and out of the seafloor removes heat from the oceanic lithosphere, alters mechanical properties and chemistry of the crust, influences ocean chemistry, and sustains deep sea biota. Several sessions reveal recent geological and geophysical observations as well as quantitative models that shed new light on the physical process of seafloor hydrogeology. The effects of seafloor topography on hydrothermal venting is of particular emphasis, and the geologic settings include both subduction zones and mid-ocean ridges.

T51E, T52B, T62B, T62C, T71F, T72A
Subduction From Top to Bottom, East to West, and Sinking to Overriding Several sessions will bring together a range of disciplines to examine the subduction processes. The variety of tools that are being used to understand subduction from top to bottom is well exemplified by recent studies centered around the idea of "the subduction factory." This year's AGU Fall Meeting will showcase the subduction factory as applied to the Izu-Bonin-Mariana system. The eastern and western subduction margins of the Pacific will also be focused on in, terms of the physics and chemistry of the subduction process and in terms of its effects on the upper, overriding plate. The AGU Fall Meeting will leave no plate out in the cold, as the structure and evolution of the incoming plate at subduction zones will receive its own attention in a special session. The range of subduction-related issues covered in the six total oral and poster sessions will make for a rich subtheme to this year's meeting.

T52E, T11A, T11E, T12A, T21D, T22A
Dynamic of Magma Storage and Transport in the Earth's Crust Recent observational and modeling studies reveal new understanding of the depths and sizes of magma chambers, mechanisms of magma transport in the crust, and the chemical and petrologic evolution of crustal magma bodies. These sessions include radar interferometric and GPS studies of surface deformation associated with magma migration, geologic and petrologic studies of magma intrusions, and geodynamic modeling efforts in linking observations to dynamical mechanisms. Pacific rim volcanoes, the Galapagos and Iceland hot spots, and intermediate-spreading mid-ocean ridges are on the list of pertinent sites.

T61C, T62A
The Hawaiian-Emperor Seamounts: New Results and Implications for the Nature of Hot Spots The bend in the Hawaiian-Emperor seamount chain is often considered to be the best example of a change in plate motion in a fixed hot spot frame of reference. However, a host of recent observational data question this basic interpretation. These sessions will highlight new results from the Ocean Drilling Program, as well as other modeling and experimental studies. Together, these works are forcing a reconsideration of the nature and evolution of the Hawaiian mantle plume and the standard inferences associated with the fixed hot spot interpretation.

T62E, T71C, T11F, T12G, T21A, T21B
Mechanics and Evolution of Fault Zones These sessions will provide interdisciplinary looks inside active fault zones, examining the role of fluids, chemistry, mechanical state, and material behavior on fault zone processes. "Fluids and Faulting: Cause and Effect" (T12G, T21A) focuses on direct influences of fault rocks and fault geometry on fluid pressure and flow as well as on the importance of fluids on fault zone evolution, architecture, and seismogenic behavior. Clearly, fault properties and active processes evolve through space and time and govern seismogenic behavior of faults. This will be examined in "Time Evolution of Chemical and Mechanical Properties of Active Fault Zones During the Earthquake Cycle" (T62E, T71C). The temporal and spatial complexity of fault zones in the Earth often requires novel theoretical descriptions of fault rheology, such as granular mechanics, which captures the discontinuous and heterogeneous nature of fault materials, properties, and friction. "Fault Zones and Granular Mechanics" (T11F, T21B) presents many of the latest studies on such methods and fault descriptions. These sessions will also link nicely with related sessions on the nonlinear dynamics of earthquakes, such as NG21B, "Damage Rheology and Physics of Earthquakes Posters," and NG62A, "Earthquake Fault Models: Current Practice and Future Challenges Posters."

T71A, T72B
Topography, Exhumation, and Orogenic Steady State These sessions highlight recent work on the development of steady state landforms. Numerical simulations are used in a variety of settings to investigate the relations between climate, erosion, and tectonics. The exhumation and thermal evolution of orogens is explored over spatial and temporal scales ranging from high-pressure metamorphism through fission track and U-Th/He thermochronology to cosmogenic exposure dating. Several studies utilize the depositional record to constrain the erosional history of adjacent orogens.

T21C, T22C, T71F, T72A
Volatiles in the Mantle Mantle volatiles are key to phenomena as diverse as melting above subducting slabs and beneath mid-ocean ridges, possible melting of the Earth's transition zone, the stability of hydrous and carbon-bearing phases at high pressures, and the rheological strengthening and weakening of the mantle. In addition, seismic wave speed, attenuation, and anisotropy are both mediated by and provide insight into volatile distributions in the mantle. These sessions will highlight the most recent contributions from seismology, geodynamics, and petrology/mineralogy that investigate the mechanical and chemical effects, the cycling, and the retention of volatile constituents in the Earth's mantle.

Volcanology, Geochemistry, and Petrology

V51A, V61C
Applications of Synchrotron Radiation in Low-Temperature Geochemistry and Environmental Science These sessions showcase many of the new techniques and applications to low-temperature and environmental chemistry that have been enabled by the advent of third-generation synchrotron radiation sources.

V51B
Metamorphism, Ultrahigh-Pressure Metamorphism, and Diamonds Posters Presentations will include studies of some of the intriguing very high pressure metamorphic terranes, including both new and previously documented localities with evidence for diamond facies conditions.

V51C, V52D, V61A, V62A
Evolution of the Igneous Rocks 2002 Edition These sessions examine present understanding of the origin and evolution of igneous rocks. This retrospective and prospective review is stimulated by the 75th anniversary of N.L. Bowen's famed lectures at Princeton, which catalyzed major advances in igneous petrology in the twentieth century.

V61D, V71C
Contemporary Chemical Geodynamics The science of chemical geodynamics, first defined almost 20 years ago, continues to evolve rapidly in light of new and increasingly precise isotopic tracers, greater sophistication of numerical modeling, and improved resolution of the seismic structure of Earth's mantle. These sessions will highlight recent advances in this field.

V62A, V71A
The Big Score: Twenty Years of Research on the Pu'u 'O'o - Kupaianaha Eruption, Kilauea Volcano, Hawai'i January 2003 will mark the 20th anniversary of the onset of the continuous eruption at Kilauea. These sessions will highlight the significant advances in our understanding of volcanic processes and volcanic hazards made possible by intensive monitoring of this remarkable natural laboratory.

V72A, V11C
Linking Chemistry and Microbiology in Seafloor Hydrothermal Systems Submarine hydrothermal vents have a rich ecology in which microbial communities are inextricably linked to their chemical environment. However, there are substantial challenges to sampling these deep-sea environments over appropriate spatial and temporal scales and therefore many fundamental questions remain unanswered. Studies presented in these sessions will feature new and innovative sampling methods, in situ measurement, and laboratory studies aimed at determining the identity of microbes present in hydrothermal vents. The results are used to deduce the relationship between community structure and chemical environment, the time evolution of microbial communities and, the effect of those communities on the chemical environment.