A31D-0125

The impact of the 2006 Indonesian biomass burning aerosols on dynamics in the UTLS studied with the GEOS-5 GCM

* Ott, L E lesley.e.ott@nasa.gov, Global Modeling and Assimilation Office, NASA GSFC, Code 610.1 Goddard Space Flight Center, Greenbelt, MD 20771, United States
Duncan, B N Bryan.N.Duncan@nasa.gov, GEST UMBC/NASA GSFC, Code 613.3 Goddard Space Flight Center, Greenbelt, MD 20771, United States
Pawson, S Steven.Pawson-1@nasa.gov, Global Modeling and Assimilation Office, NASA GSFC, Code 610.1 Goddard Space Flight Center, Greenbelt, MD 20771, United States

Previous studies have indicated that Indonesian wildfires may produce large aerosol radiative forcings and strongly influence the chemistry of the upper troposphere/lower stratosphere (UTLS). In this work, we use NASA's Goddard Earth Observing System, Version 5 (GEOS-5), atmospheric General Circulation Model (GCM) to examine the impact of these aerosols from the 2006 wildfires on dynamics in the UTLS. One-year simulations including the radiative impact of Indonesian biomass-burning aerosols are compared with simulations which omit these aerosols. Observed sea surface temperatures are used to constrain the GCM. Neither these nor the specified trace gas emissions vary among the simulations. An ensemble methodology is used to separate the role of the aerosol forcing from the potentially chaotic response of the model to perturbations. Results indicate that heating from aerosols in the upper troposphere may increase the buoyancy of air, contributing to cross-tropopause transport of CO.

A31D-0126

Characterization of Smoke Injection Into the UT/LS From Biomass Burning 1. Developing Methodologies Based on AI and CALIPSO Data

* Guan, H guan@clio.arc.nasa.gov, Bay Area Environmental Research Institute, 560 Third St West, Sonoma, CA 95476, United States
Follette, M B melanie.follette@gmail.com, Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC, 20375, United States
Lopez, J D Jimena.D.Lopez@nasa.gov, Bay Area Environmental Research Institute, 560 Third St West, Sonoma, CA 95476, United States
Esswein, R F Robert.F.Esswein@nasa.gov, Bay Area Environmental Research Institute, 560 Third St West, Sonoma, CA 95476, United States
Iraci, L T Laura.T.Iraci@nasa.gov, NASA Ames Research Ceneter, Earth Science Division, MS 245-5, Moffett Field, Mountain View, CA 94035, United States
Fromm, M mike.fromm@nrl.navy.mil, Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC, 20375, United States

Remote and in-situ observations have documented many instances of BB pollutants in the Upper Troposphere and Lower Stratosphere (UT/LS). These high-altitude injections can facilitate long-range transport of strongly-absorbing particles. In the stratosphere these particles may have an important impact on chemical composition, radiative balance, and climate. The identification of these injection events is fundamental to understanding the associated effects. In this study, we have developed a method to identify high-altitude injection events using two datasets from A-Train satellites. OMI aerosol index (AI) has been used to identify the latitude, longitude and time where particles are lofted high into the atmosphere. CALIPSO lidar images have been used to determine precisely the altitude of the plume. Synergistic observations of biomass burning smoke from the two sensors since 2006 offer an opportunity to determine the relationship between AI values and plume height. This information can then be used to derive a cutoff threshold value of AI for the identification of high-altitude injection events. The method will allow detection of the global distribution of high-altitude injection events at locations (and times) where CALIPSO data is unavailable. We will present the identification method and its application. Our companion poster (2. Methodology expansion using the HYSPLIT trajectory model) will explore methods to supplement the altitude determination of biomass burning injections presented here.

A31D-0127

Characterization of Smoke Injection Into the UT/LS From Biomass Burning. 2. Methodology Expansion Using the HYSPLIT Trajectory Model

* Follette, M B melanie.follette@nrl.navy.mil, National Research Council / Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375, United States
Fromm, M mike.fromm@nrl.navy.mil, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375, United States
Guan, H guan@clio.arc.nasa.gov, Bay Area Environmental Research Institute, 560 Third St West, Sonoma, CA 95476, United States
Lopez, J Jimena.D.Lopez@nasa.gov, Bay Area Environmental Research Institute, 560 Third St West, Sonoma, CA 95476, United States
Iraci, L Laura.T.Iraci@nasa.gov, NASA Ames Research Center, Mail Stop 245-5, Moffett Field, CA 94035, United States

High-altitude injection of aerosols and pollutants into the upper troposphere/lower stratosphere (UT/LS) can have important radiative and chemical implications for this region of the atmosphere. At these altitudes, plumes can persist for days and experience long-range transport. A methodology is outlined in our companion poster (1. Developing methodologies based on AI and CALIPSO data), describing how coincident measurements made by the OMI and CALIPSO A-Train instruments are used to determine the altitudes of smoke plumes. A relationship between plume AI values and associated altitudes can therefore be made for the CALIPSO era and extrapolated to the entire OMI and TOMS record. This methodology is expanded upon here, utilizing forward trajectories calculated using the HYSPLIT trajectory model to increase the number of possible coincidences with the CALIPSO orbit. High-altitude biomass burning plumes can then be characterized by the AI values of the original day-after plume, the change in AI as the plume degrades, and length of time it is detectable.

A31D-0128

Aircraft Observations of Seasonal Variability in Black Carbon in the Tropical Tropopause Layer

* Spackman, J R ryan.spackman@noaa.gov, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
* Spackman, J R ryan.spackman@noaa.gov, NOAA Earth System Research Laboratory, 325 Broadway R/CSD6, Boulder, CO 80305, United States
Gao, R S, NOAA Earth System Research Laboratory, 325 Broadway R/CSD6, Boulder, CO 80305, United States
Schwarz, J P, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
Schwarz, J P, NOAA Earth System Research Laboratory, 325 Broadway R/CSD6, Boulder, CO 80305, United States
Watts, L A, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
Watts, L A, NOAA Earth System Research Laboratory, 325 Broadway R/CSD6, Boulder, CO 80305, United States
Fahey, D W, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
Fahey, D W, NOAA Earth System Research Laboratory, 325 Broadway R/CSD6, Boulder, CO 80305, United States
Pfister, L , NASA, Ames Research Center, Moffett Field, CA 94035, United States
Bui, T P, NASA, Ames Research Center, Moffett Field, CA 94035, United States
Livesey, N J, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States

The role of black carbon (BC) in climate change through direct and indirect radiative forcing is still emerging. The chemistry and dynamics of the stratosphere is sensitive to radiative changes in the tropical tropopause layer (TTL) possibly induced by perturbations to BC in this region. The role of BC in altering ice cloud properties is particularly uncertain. While most BC particles are removed in the lower troposphere, a small fraction are lofted to higher altitudes via convection. Measurements of BC mass loadings have now been made in the TTL aboard the NASA WB-57F research aircraft during both summer (wet) and winter (dry) in Costa Rica. Below the TTL, BC mass mixing ratios declined sharply with altitude from the ground to approximately 5 km. In the TTL, a factor of 6 times more BC mass was measured in the wet season than the dry season. These BC mass loadings were examined using back trajectories to determine the most recent influence from convection. Depending on the BC mass loadings in the region of entrainment, convection can either dilute or enhance the background BC mass in the TTL. Results from the convective influence back trajectories suggest seasonal variability in the (1) long-range transport of clean air from convection in the Southern Hemisphere and (2) local and nonlocal convective lofting of BC from various emission sources followed by long-range transport contribute to the differences in the vertical profiles between the 2 seasons. We use satellite measurements of short-lived tracer species to examine the relative contributions of local anthropogenic, African biomass burning, and Asian anthropogenic emissions to the observed enhancement of BC in the TTL during the summer in Costa Rica. This analysis highlights the coupled processes of convection and long-range transport that control the global concentrations of BC in the TTL.

A31D-0129

Preliminary ClOOCl Cross Sections From a New Laboratory Study of the Cl Atom Yield From ClOOCl Photolysis

* Wilmouth, D wilmouth@huarp.harvard.edu, Harvard University, Department of Chemistry, 12 Oxford Street, Cambridge, MA 02138, United States
Hanisco, T tfh@huarp.harvard.edu, Harvard University, Department of Chemistry, 12 Oxford Street, Cambridge, MA 02138, United States
Stimpfle, R stimpfle@huarp.harvard.edu, Harvard University, Department of Chemistry, 12 Oxford Street, Cambridge, MA 02138, United States
Anderson, J anderson@huarp.harvard.edu, Harvard University, Department of Chemistry, 12 Oxford Street, Cambridge, MA 02138, United States

We present an overview of a new laboratory experiment designed to determine the product of the ClOOCl absorption cross section and the quantum yield of Cl atom production from ClOOCl laser photolysis at selected wavelengths between 248 and 351 nm. The experiment provides the first determination of ClOOCl cross sections via a means other than absorption spectroscopy. The Cl atom yield from ClOOCl laser photolysis is directly measured using atomic resonance fluorescence detection. This technique has the advantage of high signal to noise even when the ClOOCl cross section is small. The concentration of ClOOCl necessary to perform this experiment is reduced with the improved sensitivity of resonance fluorescence detection relative to absorption, enabling operation in a flowing system with minimal wall interaction. Cl₂, the primary contaminant in previous studies, is measured and accounted for using non-resonant molecular fluorescence. Preliminary ClOOCl cross section results at 351 nm will be presented.

A31D-0130

Experimental Study of the Kinetics of the Reaction of Acetic Acid with Hydroxyl Radicals From 255 to 355 K

* Huang, Y ywhuang@huarp.harvard.edu, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, MA 02138,
Dransfield, T J timothy.dransfield@umb.edu, Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125,
Miller, J D EM: , Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125,
Rojas, R D EM: , Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125,
Castillo, X G EM: , Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125,
Anderson, J G EM: , Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, MA 02138,

We present the experimental data of the rate constant of the reaction of OH with acetic acid over the temperature range of 255 - 355 K was determined using a high pressure flow system with laser-induced fluorescence detection of the OH radicals and FTIR spectrometry for acetic acid quantification. The rate constant displays a negative temperature dependence and can be described by the Arrhenius expression: k₁(T) = (5.81 ± 0.33) × 10^-14 exp (718 ± 16 / T) cm³ molecule ^-1 s^{- 1}, with k₁ = (6.77 ± 0.14) × 10^-13 cm³ molecule^-1 s^-1 at 295 K. The negative temperature dependence suggests a pre-reactive complex formation between the OH radicals and the acetic acid monomer, and this result is consistent with previous reports. The use of FTIR spectrometry allows for separation of the acetic acid monomer and dimer in the spectrum and gives a measurement of the acetic acid monomer that is independent of the temperature measurement and free of reliance on an equilibrium constant expression that can introduce high uncertainty. The highly sensitive laser-induced fluorescence for OH detection coupled with the FTIR spectrometry result in a rate constant measurement with low uncertainty, and the data set presented here in the temperature range of 255 - 355K serves to bridge existing data sets that are conducted either above or below room temperature.

A31D-0131

Laboratory studies of the chlorine atom yield from the photolysis of ClO dimer (ClOOCl) – experimental details.

* Hanisco, T F hanisco@huarp.harvard.edu, Harvard University, Department of Chemistry 12 Oxford St, Cambridge, MA 02138, United States
Wilmouth, D M wilmouth@huarp.harvard.edu, Harvard University, Department of Chemistry 12 Oxford St, Cambridge, MA 02138, United States
Stimpfle, R M stimpfle@huarp.harvard.edu, Harvard University, Department of Chemistry 12 Oxford St, Cambridge, MA 02138, United States
Anderson, J G anderson@huarp.harvard.edu, Harvard University, Department of Chemistry 12 Oxford St, Cambridge, MA 02138, United States

We will describe the results of experiments to determine the product of chlorine atom quantum yield and the absorption cross section of the ClO dimer, ClOOCl. The experiments use a combination of excimer laser photolysis (λ = 248 nm, 308 nm, and 351 nm) and atomic chlorine resonance fluorescence detection to determine the photolysis yield. The technique has the advantage of high signal to noise from the detection of chlorine atoms, but the disadvantage of the lack of specificity in the photolytic production of chlorine atoms. The yield of chlorine atoms at 351 nm relative to that at 248 nm will be presented in light of the known interferences, such as ClO and Cl₂. The detection of ClO, OClO, and O₃ in the system by absorption spectroscopy will be presented. The detection of Cl₂ by molecular fluorescence of the Rydberg series at 135 nm will be described.

A31D-0132

Kinetic and Thermochemical Studies of Weakly-Bound HO2 Complexes with Carboxylic acids

* Zhao, Z zhijun.zhao@eas.gatech.edu, School of Earth & Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0340,
Nicovich, J M mike.nicovich@chemistry.gatech.edu, School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332-0400,
McKee, M L mckee@chem.auburn.edu, Department of Chemistry & Biochemistry, Auburn University, College of Sciences and Mathematics, Auburn, AL 36849,
Wine, P H paul.wine@chemistry.gatech.edu, School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332-0400,
Wine, P H paul.wine@chemistry.gatech.edu, School of Earth & Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0340,

Numerous theoretical and experimental studies have suggested that HO2 radicals are able to form strong hydrogen bonds with some closed-shell species, which can potentially influence our understanding of HO2 chemistry in the upper troposphere and lower stratosphere. In this study, a laser flash photolysis-tunable diode laser absorption spectroscopy technique has been employed to study the formation of HO2 complexes with formic and acetic acids. At low temperatures, equilibration kinetics have been observed, allowing adduct formation and dissociation rate coefficients to be obtained and adduct binding enthalpies to be determined. This is the first experimental study of the HO2-carboxylic acid complexes and the binding energies are in good agreement with the most recent theoretical estimates. The potential role of HO2-RC(O)OH adducts in atmospheric chemistry will be discussed.

A31D-0133

Revisiting the SOLVE ClOOCl and ClO measurements in consideration of the Pope et al., 2007 results.

* Stimpfle, R M stimpfle@huarp.harvard.edu, CCB/SEAS Harvard University, 12 Oxford Street, Cambridge, MA 02138, United States
Wilmouth, D M wilmouth@huarp.harvard.edu, CCB/SEAS Harvard University, 12 Oxford Street, Cambridge, MA 02138, United States
Anderson, J G anderson@huarp.harvard.edu, CCB/SEAS Harvard University, 12 Oxford Street, Cambridge, MA 02138, United States

The interpretation of the SOLVE measurements of ClOOCl and ClO has recently acquired renewed interest with the publication of new ClOOCl cross section measurements (Pope et al, 2007) that are significantly smaller than expected. The SOLVE analysis showed agreement with J values based upon the JPL 2002 or Burkholder 1990 cross sections, dependent upon various values for the rate constant for dimer production. J values based upon Pope are currently not in agreement with the SOLVE observations and/or their analysis. As various hypotheses emerge to possibly rationalize the Pope results, it is worthwhile to consider two critical constraints that the SOLVE halogen data place on any newly considered Clx photochemistry. The first constraint is the lack of a detectable Cl atom signal in the observed background signal at the temperature used for thermal dissociation of ClOOCl. The second constraint is the observed SZA dependence of the partitioning of ClO and ClOOCl. Here we present evidence of the Cl atom constraint.

A31D-0134

Comparison of MMS Pressure, Temperature, and Horizontal Wind Data With CFH/Ozonesonde and AVAPS Dropsonde Profiles Collected During TC4

* Dean-Day, J Jonathan.M.Dean-Day@nasa.gov, Bay Area Environmental Research Institute, 560 Third St. West, Sonoma, CA 95476, United States
Bui, T Thaopaul.V.Bui@nasa.gov, NASA - Ames Research Center, MS 245-5, Moffett Field, CA 94035, United States
Chang, C Cecilia.S.Chang@nasa.gov, Bay Area Environmental Research Institute, 560 Third St. West, Sonoma, CA 95476, United States
Vömel, H Holger.Voemel@dwd.de, GRUAN Lead Center Deutscher Wetterdienst, Meteorologisches Observatorium Lindenberg -- Am Observatorium 12 -- 15848 Tauche, Lindenberg, 15848, Germany
Korn, E korn@ucar.edu, University Corporation for Atmospheric Research, Foothills Lab 1 3450 Mitchell Lane, Boulder, CO 80301, United States

During the 2007 Tropical Composition, Cloud and Climate Coupling Experiment (TC⁴), the Meteorological Measurement System (MMS) derived pressure, temperature and 3-D wind data aboard the NASA DC-8 and WB-57 aircraft. Using GPS altitude as a common vertical coordinate, profiles of airborne data during climb and descent were compared with the same parameters computed following balloon-borne ascent of the Cryogenic Frostpoint Hygrometer (CFH) / Ozonesonde from Juan Santamaria Airport, as well as during rapid descent of Airborne Vertical Advanced Profiling System (AVAPS) Dropsondes, released from the DC-8 aircraft at various locations above Costa Rica and the surrounding oceans. Profiles are selected to minimize natural variability due to space and time separation between platforms. In addition, profile pressure data are compared with an assumed hydrostatic descent from pre-selected altitudes. Mean differences in pressure, temperature, and winds will be discussed with respect to instrument accuracy.

A31D-0135

Validation of AIRS Version 5 ozone

* Irion, F W bill.irion@jpl.nasa.gov, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
Fetzer, E J eric.fetzer@jpl.nasa.gov, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
Lee, S sung-yung.lee@jpl.nasa.gov, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
Osterman, G B gregory.b.osterman@jpl.nasa.gov, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States

The Atmospheric Infrared Sounder (AIRS), currently on the EOS-Aqua satellite, retrieves ozone column and profile information from nadir viewing of IR emittance. We present validation of the Version 5 observations of ozone columns and profiles using coincident ozonesondes and other satellite-based observations. In particular, we utilize vertical averaging kernels now provided with AIRS Version 5 results, and compare AIRS results under different cloud conditions.

A31D-0136

Ozone Climatology Using OSIRIS Spectrograph Data and the SaskMART Ozone Retrieval Technique

* Roth, C Z chris.roth@usask.ca, University of Saskatchewan, 116 Science Place, Saskatoon, SK S7N 5E2, Canada
Degenstein, D doug.degenstein@usask.ca, University of Saskatchewan, 116 Science Place, Saskatoon, SK S7N 5E2, Canada
Bourassa, A adam.bourassa@usask.ca, University of Saskatchewan, 116 Science Place, Saskatoon, SK S7N 5E2, Canada

The OSIRIS instrument on-board the Odin satellite has been collecting spectrally dispersed vertical profiles of the atmospheric limb radiance since launch in February, 2001. These data, combined with the SaskMART retrieval algorithm, are used to derive vertical profiles of the ozone number density from the cloud tops to approximately 60~km altitude with a vertical resolution of approximately 2~km. The relatively high global coverage afforded by this technique, combined with the increasingly valuable length of the mission, provides a highly useful data set for the development of an ozone climatology at upper tropospheric through stratospheric altitudes. The development of such a climatology is presented in this work, including a discussion of anomalies and trends found in the data set.

A31D-0137

Spatial Structure in the UTLS Ozone Distribution Obtained by Assimilating EOS-Aura Data in GEOS-5

* Wargan, K Krzysztof.Wargan-1@nasa.gov, Science Applications International Corporation, 4600 Powder Mill RD, Beltsville, MD 20705, United States
* Wargan, K Krzysztof.Wargan-1@nasa.gov, NASA/Global Modeling and Assimilation Office, Goddard Space Flight Center, Greenbelt, MD 20771, United States
Pawson, S Steven.Pawson-1@nasa.gov, NASA/Global Modeling and Assimilation Office, Goddard Space Flight Center, Greenbelt, MD 20771, United States
Sienkiewicz, M Meta.E.Sienkiewicz@nasa.gov, Science Applications International Corporation, 4600 Powder Mill RD, Beltsville, MD 20705, United States
Sienkiewicz, M Meta.E.Sienkiewicz@nasa.gov, NASA/Global Modeling and Assimilation Office, Goddard Space Flight Center, Greenbelt, MD 20771, United States
Stajner, I Ivanka.Stajner@noblis.org, Noblis, Incorporated, 3150 Fairview Park Drive South, MS F540, Falls Church, VA 22042, United States

This study examines the structure in assimilated ozone distributions in the upper troposphere-lower stratosphere (UTLS). The analysis is performed using the Goddard Earth Observing System, Version 5 (GEOS-5) data assimilation system (DAS), which has been modified to ingest ozone data from EOS-Aura. Retrievals of total ozone from OMI and stratospheric profiles from MLS are assimilated, using observation errors provided with the retrievals. Previous work using GEOS-4, reported in Stajner et al. (JGR, 2007), demonstrated that these data provide a robust constraint to capture the time-dependent, 3D structure of stratospheric ozone and, with some limitations, the horizontal structure of tropospheric ozone column. Independent observations are used to evaluate the nature of horizontal and vertical structures in the assimilated ozone in the UTLS. MOZAIC data enable validation of the quasi-horizontal variations, while ozone sondes and HIRDLS retrievals allow evaluation of the vertical structure. The work takes advantage of the high horizontal resolution capabilities of GEOS-5 to examine the finest scales that can be captured in the assimilation process, as well as examining the mechanisms that lead to the generation of these spatial structures.

A31D-0138

Improved Tropopause Based Ozone Climatology For Infrared Satellite Retrievals

* Wei, J jennifer.wei@noaa.gov, NOAA/NESDIS/STAR, 5200 Auth Rd., Camp Springs, MD 20746,
* Wei, J jennifer.wei@noaa.gov, Perot Systems Government Services, Inc., 8270 Willow Oaks Corporate Dr., Fairfax, VA 22031,
Maddy, E Eric.Maddy@noaa.gov, NOAA/NESDIS/STAR, 5200 Auth Rd., Camp Springs, MD 20746,
Maddy, E Eric.Maddy@noaa.gov, Perot Systems Government Services, Inc., 8270 Willow Oaks Corporate Dr., Fairfax, VA 22031,
Pan, L liwen@ucar.edu, NCAR/ACD, 1850 Table Mesa Dr., Boulder, CO 80305,
Barnet, C Chris.Barnet@noaa.gov, NOAA/NESDIS/STAR, 5200 Auth Rd., Camp Springs, MD 20746,

The behaviors of extratropical ozone near upper troposphere and lower stratosphere (UT/LS) are best characterized using relative tropopause altitude coordinates. In this study, we re-construct ozone climatology using best available ozonesondes (WOUDC, SHADOZ, CMDL) in two different vertical coordinates: fixed pressure altitude and relative tropopause altitude. We will show results using the current retrieval algorithm from the EOS-Aqua Atmospheric Infrared Sounder (AIRS) and a novel optimal estimation algorithm using the two re-constructed ozone climatologies.

A31D-0139

ENSO Variability of the Southern Hemisphere Subtropical Westerly Jet, Ozone Croissant, Ozone Hole, and Polar Stratospheric Clouds

* Hitchman, M H matt@aos.wisc.edu, University of Wisconsin - Madison, 1225 West Dayton Street, Madison, WI 53706,
Rogal, M J mjrogal@wisc.edu, University of Wisconsin - Madison, 1225 West Dayton Street, Madison, WI 53706,
Parker, A parker2@wisc.edu, University of Wisconsin - Madison, 1225 West Dayton Street, Madison, WI 53706,
Zachar, N A nazachar@wisc.edu, University of Wisconsin - Madison, 1225 West Dayton Street, Madison, WI 53706,

An important teleconnection exists between tropical convective outflow in the UTLS and climatological structures in the austral winter and spring. Lagrangian trajectories and a detailed momentum budget show that the Australian subtropical westerly jet (ASWJ) is due to outflow from convection over SE Asia and Indonesia. The ASWJ lies immediately equatorward of the zonally asymmetric maximum in column ozone, which is known as the ozone croissant (OC). The OC extends from the Southern Indian Ocean past Australia into the Pacific and reaches maximum zonal asymmetry during October. The ozone hole is usually displaced off of the pole away from the OC toward the Atlantic sector. The interaction of monsoon anticyclones, synoptic Rossby waves, and extratropical travelling planetary waves in maintaining the OC is discussed. The structure of the OC is intimately linked to the structure of the ozone hole, polar vortex temperatures, and polar stratospheric clouds (PSCs). The OC is also an integration of hemispheric transport, which can reflect tropical influences, including that of the El Nino Southern Oscillation (ENSO). During La Nina the polar vortex is stronger and displaced farther off the pole, the OC is more zonally asymmetric, and there are more PSCs and colder temperatures in the polar vortex above 16 km. During El Nino the polar vortex is weaker, more centered on the pole, midlatitude ozone is arranged in an annulus, and there are fewer PSCs and warmer temperatures in the polar vortex above 16 km. A dynamical explanation is suggested for this interannual variability which contrasts the strong longitudinally-focussed outflow in the UTLS from Indonesia during La Nina with the more longitudinally-dispersed, milder outflow events during El Nino.

A31D-0140

Relation of secondary ozone peak to tropopause characteristics

* Lee, Y s834@yonsei.ac.kr, Yonsei University, 134 Sinchon-dong, Seodaemoon-gu, Seoul, 120-749, Korea, Republic of
Kim, J jkim2@yonsei.ac.kr, Yonsei University, 134 Sinchon-dong, Seodaemoon-gu, Seoul, 120-749, Korea, Republic of
Hwang, S shhwang@kari.re.kr, Korea Aerospace Research Institute, 115 Gwahangno, Yuseong, Daejeon, 305-333, Korea, Republic of

Tropopause has played an important role in mass exchanges bordering convective tropopause and stable stratosphere. However, there is not a clear boundary between them. From stratosphere to troposphere or from troposphere to stratosphere, the matter exchange (STE or TSE) happens across the tropopause. Therefore to understand the mass exchange between them, it requires detailed studies about the characteristics of tropopause first. In this study, Lapse Rate Tropopause (LRT), Coldest-Point Tropopause (CPT), Dynamic Tropopause (DT) and Ozone Tropopause (OT) are used as the definitions of tropopause. On the other hand, over the mid-latitude, the secondary ozone peak happens frequently in the lower stratosphere and upper troposphere. The secondary ozone peak can be explained by STE phenomena but STE mechanism is not fully understand yet. In many cases of the secondary ozone peak, temperature profile shows little peak at the similar level of the secondary ozone peak. In this case, CPT shows at higher altitude than others and double LRT happens because of the disturbed temperature profiles. These results are related to STE, which gives a clue to understand the formation of tropopauses related to STE.

A31D-0141

Climatology of Wave-Mean Flow Interaction and Stratospheric Ozone Transport

* Monier, E emonier@ucdavis.edu, Atmospheric Science Program, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
Weare, B C bcweare@ucdavis.edu, Atmospheric Science Program, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States

The troposphere-stratosphere coupling is currently drawing a lot of interest since the stratosphere was shown to have a significant impact on climate change. In this study, the Transformed Eulerian-Mean formulation and the ECMWF ERA-40 reanalysis are used to investigate the processes responsible for the wave-mean flow interaction. In addition, ozone seasonal variability is also studied in order to better understand the dynamical transport of ozone and its significance compared to the radiative-chemical effects. Results show that the dissipative forces and the advection by the residual mean meridional circulation have a significant contribution to the time rate of change of the stratospheric polar vortex. The dissipative forces has a magnitude comparable to that of the Eliassen-Palm Flux divergence or the residual mean meridional circulation and is consistent in location and magnitude with an orographic gravity wave drag forcing or the fact that the Brewer Dobson circulation is too strong in the ERA-40 reanalysis. In addition, the ozone chemical net production term is consistent with ozone production in the Tropics and ozone loss in early winter at midlatitude. The ozone transport is dominated by advection by the vertical component of the residual mean meridional circulation and by the divergence of the net eddy flux horizontal component. Overall, the Northern hemisphere is dominated by stationary processes due to the influence of orography and land-sea heating contrasts while the Southern hemisphere is marked by a combination of stationary and transient processes that have very different contributions.

A31D-0142

Dynamical Impacts of Stratospheric QBO on the Extratropical Atmosphere

* Naoe, H hnaoe@mri-jma.go.jp, Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052, Japan
Shibata, K kshibata@mri-jma.go.jp, Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052, Japan

The observed daily and monthly data of 40-year ERA Reanalysis and the simulation data of 125-year (5members times recent past 25 years) simulation are analyzed to investigate the effects of the equatorial quasi-biennial oscillation (QBO) on the large scale dynamics in the extratropical stratosphere and troposphere. A middle-atmosphere ensemble simulation of the recent past 25 years from 1980 to 2004 has been carried out with the chemistry climate model (CCM) of the Meteorological Research Institute (MRI), based on the REF1 common scenario of chemistry-climate model validation activity (CCMVAL) using sea- surface temperature (SST), sea-ice, well-mixed GHGs, halogens, halons, the 11-year solar cycle, and volcanic aerosols. Five members with slightly different initial conditions are integrated in the ensemble simulation. All five members reproduced the QBO although the phase of the QBO is different from each other. Composites of the data in northern winter months with respect to the westerly or easterly phase of the QBO show that the stratospheric polar vortex is colder and stronger in the westerly phase. As a result, the most significant composite difference of the temperature is found near the tropopause in high latitudes, although the frequency distributions of the temperature for the two phases of the QBO overlap each other heavily.

A31D-0143

High Static Stability in the Mixed Layer Above the Extratropical Tropopause

* Kunz, A a.kunz@fz-juelich.de, Institut für Chemie und Dynamik der Geosphäre: Troposphäre (ICG-2), Forschungszentrum Jülich, Jülich, 52425, Germany
* Kunz, A a.kunz@fz-juelich.de, Institut für Chemie und Dynamik der Geosphäre: Stratosphäre (ICG-1), Forschungszentrum Jülich, Jülich, 52425, Germany
Konopka, P p.konopka@fz-juelich.de, Institut für Chemie und Dynamik der Geosphäre: Stratosphäre (ICG-1), Forschungszentrum Jülich, Jülich, 52425, Germany
Müller, R ro.mueller@fz-juelich.de, Institut für Chemie und Dynamik der Geosphäre: Stratosphäre (ICG-1), Forschungszentrum Jülich, Jülich, 52425, Germany
Schiller, C c.schiller@fz-juelich.de, Institut für Chemie und Dynamik der Geosphäre: Stratosphäre (ICG-1), Forschungszentrum Jülich, Jülich, 52425, Germany

A strong relationship between the static stability N² and the strength of mixing in the mixed layer above the extratropical tropopause is evident from in-situ data observed during the SPURT aircraft campaigns. We present a method for quantifying the strength of mixing from O₃/CO tracer correlations and we find that N² is positively correlated with the strength of mixing. Age of air simulations with the CLaMS model reveal two different types of mixed regions. One type consisting of older airmasses with higher values of N² which are created by radiative adjustment after a mixing event. These airmasses are within the TIL (Tropopause Inversion Layer), considering the TIL as part of the mixing layer. The second type comprises younger airmasses with somehow lower stratospheric N² values within the mixing layer, because of recent intrusion processes due to the permeability or so-called mid-latitude-breaks associated with the jet stream. With the help of radiative transfer calculations we simulate the influence of trace gases such as O₃ and H₂O on the temperature gradient and thus on the static stability above the tropopause in the idealized case of non-mixing (L-shape) O₃ and H₂O profiles and in the reference case of mixed profiles. Within the altitude range of the SPURT campaigns the mean vertical SPURT profiles are used as reference, which are fitted to the HALOE climatological profiles above the UT/LS.

A31D-0144

Response of the tropical tropopause temperature to changes in tropical sea surface temperatures : role of vertical eddy heat flux

* Yoshida, K kohei@ees.hokudai.ac.jp, Graduate School of Environmental Science, Hokkaido University, Kita 10 Nishi 5, Kitaku, Sapporo, 060-0810, Japan
Yamazaki, K yamazaki@ees.hokudai.ac.jp, School of Enviromental Earth Science, Hokkaido University, Kita 10 Nishi 5, Kitaku, Sapporo, 060-0810, Japan

The tropical tropopause (TT) temperature is controlled both by midlatitude stratospheric pump and equatorial waves caused by tropical convection. To understand how the TT temperature is influenced by tropical convection, variations of TT temperature with change in tropical sea surface temperature (SST) distribution are examined by using an atmospheric general circulation model (CCSR/NIES AGCM). We performed two types of experiments. In one type of runs, zonal asymmetry of tropical SST is changed (S' runs). In the other type, tropical SSTs are uniformly changed (S runs). For all experiments, adiabatic cooling/heating induced by change in Brewer-Dobson circulation is dominant in the tropical lower stratosphere (50 hPa), which is consistent with stratospheric pump. However, at the TT level (90 hPa), the adiabatic effect is not a main factor. In S' runs, the enhancement (weakening) in zonal asymmetry of the tropical SST causes the cooling (warming) of zonal mean TT temperature by vertical eddy heat flux (\overline{w' θ'}) associated with a Gill-type equatorial wave pattern. The vertical eddy heat flux is important for variations of the zonal mean TT temperature especially for interannual variation associated with ENSO.

A31D-0145

Warming Maximum in the Tropical Upper Troposphere Deduced From Thermal Winds

* Allen, R J robert.allen@yale.edu, Yale University, Department of Geology and Geophysics, New Haven, CT 06520, United States
Sherwood, S C steven.sherwood@yale.edu, Yale University, Department of Geology and Geophysics, New Haven, CT 06520, United States

Climate models and theoretical expectations have predicted that the upper troposphere should be warming faster than the surface. Surprisingly, direct temperature observations from radiosonde and satellite data have often not shown this expected trend. However, non-climatic biases have been found in such measurements. Here we apply the thermal-wind equation to wind measurements from radiosonde data, which seem to be more stable than the temperature data. We derive estimates of temperature trends for the upper troposphere to the lower stratosphere since 1970. Over the period of observations, we find a maximum warming trend of 0.65 ± 0.47 K per decade near the 200 hPa pressure level, below the tropical tropopause. Warming patterns are consistent with model predictions except for small discrepancies close to the tropopause. Our findings are inconsistent with the trends derived from radiosonde temperature datasets and from NCEP reanalyses of temperature and wind fields. The agreement with models increases confidence in current model-based predictions of future climate change.

A31D-0146

Identification of large-scale stratospheric 10-hour waves in the Antarctic polar vortex

* Gelinas, L J Lynette.J.Gelinas@aero.org, The Aerospace Corporation, 2350 E El Segundo Blvd, El Segundo, CA 90245,
Walterscheid, R Richard.Walterscheid@aero.org, The Aerospace Corporation, 2350 E El Segundo Blvd, El Segundo, CA 90245,
Mechoso, C R mechoso@atmos.ucla.edu, UCLA Dept Atmospheric Sciences, 405 Hilgard Ave, Los Angeles, CA 90045, United States
Schubert, G schubert@ucla.edu, UCLA, 595 Charles Young Dr E, Los Angeles, CA 90095, United States

The CNES VORCORE stratospheric balloon campaign consisted of 27 super-pressure constant density balloons launched into the Antarctic polar vortex in September and October of 2005. We use balloon measurements of stratospheric wind, air pressure and temperature to study vortex dynamics and wave dynamics within the vortex, with the goal of constraining parameterizations of gravity wave momentum fluxes. The gravity wave spectrum extends from the Brunt-Vaisala frequency to the inertial frequency, which has a latitude-dependent period ≥³ 12 h. In contrast to measurements made in the Arctic polar vortex, we find no distinct inertial peak in the wind spectrum in the Antarctic balloon data. Instead, a prominent peak near 10 h is observed. Waves with periods of about ten hours fall within the gravity wave part of the spectrum, and have therefore been assumed to be small-scale inertia-gravity waves. However, we find that quasi-ten hour waves in the VORCORE data are often large-scale disturbances that can be stable over week-long periods. Analyses of balloon-assimilated GEOS-5 model data have not yet yielded a robust explanation for this wave mode. We present data showing the large-scale dynamics of the ten-hour wave mode over the lifetime of the polar vortex and compare results from the GEOS-5 analysis with assimilated balloon data. The analysis seems to suggest that the 10 h wave is a large-scale disturbance trapped by the Antarctic polar vortex and possibly forced by dynamics within the vortex.

A31D-0147

Polar night vortex breaking and air mixing in the southern stratosphere

de la Camara, A acamarai@atmos.ucla.edu, Departamento de Geofisica y Meteorologia, Universidad Complutense de Madrid, Facultad de Ciencias Fisicas, Madrid, 28040, Spain
de la Camara, A acamarai@atmos.ucla.edu, Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90095, United States
* Mechoso, C R mechoso@atmos.ucla.edu, Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90095, United States
Walterscheid, R L Richard.Walterscheid@aero.org, Space Sciences Department, The Aerospace Corporation, PO Box 92957 - M2/260, Los Angeles, CA 90009, United States
Gelinas, L J Lynette.J.Gelinas@aero.org, Space Sciences Department, The Aerospace Corporation, PO Box 92957 - M2/260, Los Angeles, CA 90009, United States
Ide, K , Department of Earth and Space Sciences, Institute of Geophysics and Planetary Physics, UCLA 405 Hilgard Ave., Los Angeles, CA 90095, United States
Schubert, G schubert@ucla.edu, Department of Earth and Space Sciences, Institute of Geophysics and Planetary Physics, UCLA 405 Hilgard Ave., Los Angeles, CA 90095, United States

The present paper addresses issues of vortex breaking and air mixing during the final warming of the Southern Hemisphere stratosphere by using a unique set of in-situ observations collected during the spring of 2005. During this period, the Stratèole/Vorcore project launched 27 superpressure balloons (SPBs) from McMurdo, Antarctica. The SPBs drifted for several weeks on two different isopycnic levels in the lower stratosphere. We describe outstanding features of the balloon trajectories and compare them with simulated trajectories obtained on the basis of the velocity field from the GEOS-5 and NCEP/NCAR reanalyses. Next, we examine the balloon trajectories in the context of the Lagrangian properties of the stratospheric flow. To display Lagrangian coherent structures of the flow and gain insight on the mechanisms responsible for the horizontal transport of air inside and outside the well-isolated vortex we compute finite-time Lyapunov Exponents (FTLE). It is shown that a combination of isentropic analysis and FTLE distributions helps to understand the balloon crossing of the polar vortex edge and air mixing along the vortex's periphery.

http://www.cnes.fr/web/5935-strateole-vorcore.php

A31D-0148

The Semidiurnal Westward s=1 Tide in the Stratosphere

Mechoso, C R mechoso@atmos.ucla.edu, UCLA Department of Atmospheric and Oceanic Sciences, 7127 Math Sciences Building 405 Hilgard Avenue, Los Angeles, CA 90095,
* Walterscheid, R L Richard.Walterscheid@aero.org, The Aerospace Corporation, MS M2-260 POB 92957, Los Angeles, CA 90009,
Gelinas, L J Lynette.J.Gelinas@aero.org, The Aerospace Corporation, MS M2-260 POB 92957, Los Angeles, CA 90009,
Schubert, G schubert@ucla.edu, UCLA Department of Earth and Space Sciences, 595 Charles Young Drive East, Box 951567, Los Angeles, CA 90095,

The semidiurnal westward propagating zonal wavenumber 1 tide (2, 1) is the dominant tide in the high- latitude wind field in the upper mesosphere during the late spring and summer. Observed peak wind speeds are ~ 30 m/s. Simulations agree with observations in showing a dominant (2, 1) tide in the upper mesosphere with about the correct amplitude at high polar latitudes. In model simulations the (2, 1) tide originates in a nonlinear interaction between the migrating semidiurnal tide (2, 2) and a stationary s=1 planetary wave. The interaction occurs in the stratosphere and mesosphere. However, stationary planetary waves are essentially absent from the summertime stratosphere and mesosphere so the occurrence of the predicted (2, 1) tide in the summer mesosphere originates via an interaction in the winter hemisphere. Observations and simulations in the mesosphere indicate a connection with the zero wind line in the zonally averaged zonal winds. The models (Angelas i Coll and Forbes, 2002, Aso, 2007) agree in showing that the (2,1) tide is confined to the upper mesosphere. We have analyzed results from the GEOS-5 assimilation model and find a significant stratospheric (2, 1) tide. We have also analyzed balloon data from the CNES VORCORE campaign in which a total of 27 balloons drifted in the Antarctic polar stratospheric vortex during the late summer and spring of 2005, and confirm the existence of the (2, 1) tide. This is the first observation of a (2, 1) tide in the stratosphere insofar as we are aware. The existence of this tide in the stratosphere is hard to understand in terms of energy propagation from the winter hemisphere guided by the zero wind line, since this would guide energy into the mesosphere rather than the stratosphere. We will present the height- latitude structure of the (2, 1) tide in the Antarctic spring and will show its correlation with the zero wind line and wave energy flux found from the GEOS-5 data assimilation model.

A31D-0149

Study on the Spatial and Temporal Variability of Stratosphere-Troposphere Exchange with A-Train Observations

* Kollonige, D W dwicks1@umbc.edu, University of Maryland Baltimore County, Department of Physics 1000 Hilltop Circle, Baltimore, Md 21250, United States
McMillan, W mcmillan@umbc.edu, University of Maryland Baltimore County, Department of Physics 1000 Hilltop Circle, Baltimore, Md 21250, United States
Sparling, L sparling@umbc.edu, University of Maryland Baltimore County, Department of Physics 1000 Hilltop Circle, Baltimore, Md 21250, United States
Avery, M m.a.avery@larc.nasa.gov, NASA Langley Research Center, MS 483 NASA LaRC, Hampton, Va 23681, United States
Diskin, G glenn.s.diskin@nasa.gov, NASA Langley Research Center, MS 483 NASA LaRC, Hampton, Va 23681, United States
Sachse, G g.w.sachse@larc.nasa.gov, NASA Langley Research Center, MS 483 NASA LaRC, Hampton, Va 23681, United States
Browell, E edward.v.browell@nasa.gov, NASA Langley Research Center, MS 401a NASA LaRC, Hampton, Va 23681, United States
Hair, J W j.w.hair@larc.nasa.gov, NASA Langley Research Center, MS 401a NASA LaRC, Hampton, Va 23681, United States

An understanding of isentropic transport of trace atmospheric constituents near the jet stream and frontal boundaries provides insight to the coupled stratosphere-troposphere system. Observations from NASA's A- Train satellites can assist in the determination of the global frequency, distribution and spatial extent of irreversible mixing of chemical species due to stratosphere-troposphere exchange (STE). The Tropospheric Emission Sounder (TES) and HIgh Resolution Dynamics Limb Sounder (HIRDLS) onboard the Aura satellite yield high vertical resolution profiles of ozone, water vapor, and other trace species that capture the vertical structure of STE along upper tropospheric fronts associated with the jet stream as well as cut-off low- pressure systems. The Atmospheric InfraRed Sounder (AIRS) onboard the Aqua satellite supplies wider horizontal coverage of the same atmospheric tracers near STE. Together, these A-Train instruments provide a more complete three-dimensional view of STE than previously possible. We explore the temporal and spatial evolution of STE events over the Pacific Ocean originating off the eastern coast of China and traveling along the storm track to the North American west coast, during NASA's Intercontinental Chemical Transport Experiment – Phase B (INTEX-B) in April and May of 2006. To study the variability of the STE events, we use chemical and dynamical analyses, including tracer-tracer correlations from A-Train observations and potential vorticity gradients from the NCEP's NARR (North American Regional Reanalysis) data in the vicinity of stratosphere-to-troposphere transport. We also compare our observations with in-situ and aircraft remote sensing measurements of similar trace gases evaluating the satellite instruments' sensitivity in the troposphere and stratosphere.

A31D-0150

MJO in four years of EOS MLS UT/LS Temperature and Composition

* Schwartz, M J michael.j.schwartz@jpl.nasa.gov, NASA Jet Propulsion Laboratory / California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109, United States
Waliser, D E duane.e.waliser@jpl.nasa.gov, NASA Jet Propulsion Laboratory / California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109, United States
Tian, B baijun.tian@jpl.nasa.gov, Joint Institute for Regional Earth System Science and Engineering, UCLA, 9258 Boelter Hall Box 957228, Los Angeles, CA 90095, United States

Preliminary work with EOS MLS v1.5 cloud ice and water vapor fields showed the strong imprint of the Madden-Julian oscillation in tropical upper-tropospheric and TTL hydrological fields. Four years of v2.2 MLS fields including IWC, H2O, temperature, CO and O3 are now available. Analysis provides a multi-parameter construct useful in validating and improving the parameterization of convection, clouds, cloud-microphysics and TTL composition in MJO modeling.

A31D-0151

Study of new Particle Formation in the Upper Troposphere and Lower Stratosphere Using WACCM/CARMA

* English, J M jason.english@colorado.edu, University of Colorado at Boulder Laboratory for Atmospheric and Space Physics, 392 UCB, Boulder, CO 80309-0392, United States
Toon, O B brian.toon@lasp.colorado.edu, University of Colorado at Boulder Laboratory for Atmospheric and Space Physics, 392 UCB, Boulder, CO 80309-0392, United States
Mills, M J mills@colorado.edu, University of Colorado at Boulder Laboratory for Atmospheric and Space Physics, 392 UCB, Boulder, CO 80309-0392, United States
Yu, F yfq@asrc.cestm.albany.edu, Atmospheric Sciences Research Center State University of New York at Albany, 251 Fuller Road, Albany, NY 12203, United States

Nucleation mode sulfate particles are known to exist in the Upper Troposphere - Lower Stratosphere (UTLS) region; however, the nucleation mechanism(s) and the role of these particles in the aerosol burden in the UTLS region are not well understood. We use WACCM/CARMA, a three-dimensional chemistry climate model based upon the Whole-Atmosphere Community Climate Model (WACCM) with sectional microphysics from the Community Aerosol and Radiation Model for Atmospheres (CARMA) to simulate the formation and evolution of sulfuric acid aerosols in the UTLS. We will compare the particle size distributions and aerosol spatial distributions predicted with two different binary homogeneous nucleation schemes, and an up-to-date ion nucleation scheme. The relative contribution of homogeneous nucleation versus ion nucleation to aerosol burden in the UTLS region will be discussed.

A31D-0152

Cloud Particle Size and Water/Ice Ratio Estimation using the DMSP SSMIS Sounder

* Peng, G S Grace.S.Peng@aero.org, The Aerospace Corporation, P.O. Box 92957 - M1/102, Los Angeles, CA 90009-2957, United States
Fote, A A Alfred.A.Fote@aero.org, The Aerospace Corporation, P.O. Box 92957 - M1/102, Los Angeles, CA 90009-2957, United States
Wu, D L Dong.L.Wu@jpl.nasa.gov, Jet Propulsion Laboratory, M/S 183-701 4800 Oak Grove Drive, Pasadena, CA 91109, United States
Boucher, D J Donald.J.Boucher@aero.org, The Aerospace Corporation, P.O. Box 92957 - M1/102, Los Angeles, CA 90009-2957, United States
Thomas, B H Bruce.H.Thomas@aero.org, The Aerospace Corporation, P.O. Box 92957 - M1/102, Los Angeles, CA 90009-2957, United States
Kishi, A M Arlene.M.Kishi@aero.org, The Aerospace Corporation, P.O. Box 92957 - M1/102, Los Angeles, CA 90009-2957, United States

The Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager/Sounder (SSMIS) is a next-generation passive conically scanning microwave radiometer. It combines both imaging and sounding capabilities of current operational instruments, SSM/I, SSM/T-1 and SSM/T-2. It also improves the capability of temperature sounding by providing profiles from the surface up to 70 km altitude with higher spatial resolutions (~37.5 for lower air and ~75 km for upper air). DMSP Flight 17 launched on 4 November 2006 from Vandenberg Air Force Base carrying the second SSMIS sounder. During the SSMIS Cal/Val period, cold patches were observed in the 50-55 GHz temperature sounding channels at low latitudes. Cold patches were also more apparent in the horizontal polarization (H- pol) than the Vertical polarization (V-pol) channels. A difference in sensitivity of the H-pol and V-pol channels gives the ratio of water to ice in the clouds. Subsequent investigation showed that these patches appeared in the 91.6 GHz channels but not the 37 GHz channels. This information, together with the theoretical scattering efficiency for spherical particles of various sizes, gives an upper bound of < 2 mm diameter for water and ice particles that may not be detected by SSMIS operational 'cloud clearing' algorithms.

Authors (2008), Title, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract xxxxx-xx