A33H-01 INVITED 

Transport and mixing of chemical airmasses in idealized baroclinic life cycles

* Polvani, L M (lmp@columbia.edu), Columbia University, Department of Applied Physics & Applied Mathematics, 500 West 120th Street, Room 216, New York, NY 10027, Esler, J G), University College London, Department of Mathematics, Gower Street, London, WC1E 6BT, United Kingdom

The transport, mixing, and three-dimensional evolution of chemically distinct airmasses within growing baroclinic waves are studied in idealized, high-resolution, life cycle experiments using suitably initialized passive tracers, contrasting the two well-known life cycle paradigms, distinguished by predominantly anticyclonic (LC1) or cyclonic (LC2) flow at upper levels. It is found that stratosphere-troposphere exchange differs significantly between the two life cycles. Specifically, transport from the stratosphere into the troposphere is significantly larger for LC2 (typically by 50%), due to the presence of large and deep cyclonic vortices that create a wider surf zone than for LC1. In contrast, the transport of tropospheric air into the stratosphere is nearly identical between the two life cycles. The mass of boundary layer air uplifted into the free troposphere is similar for both life cycles, but much more is directly injected into the stratosphere in the case of LC1 (fourfold, approximately). However, the total mixing of boundary layer with stratospheric air is larger for LC2, owing to the presence of the deep cyclonic vortices that entrain and mix both boundary layer air from the surface and stratospheric air from the upper levels. For LC1, boundary layer and stratospheric air are brought together by smaller cyclonic structures that develop on the poleward side of the jet in the lower part of the middleworld, resulting in correspondingly weaker mixing. As both the El Nino-Southern Oscillation and the North Atlantic Oscillation are correlated with the relative frequency of life cycle types, corresponding changes in chemical transport and mixing are to be expected. http://www.columbia.edu/~lmp/pubs.html

A33H-02 

In situ measurements of nitric acid and ozone in the upper troposphere and lower stratosphere

* Popp, P J (peter.j.popp@noaa.gov), NOAA Earth Systems Research Laboratory, 325 Broadway, R/CSD6, Boulder, CO 80305, Marcy, T P (tpmarcy@hotmail.com), NOAA Earth Systems Research Laboratory, 325 Broadway, R/CSD6, Boulder, CO 80305, Gao, R (rushan.gao@noaa.gov), NOAA Earth Systems Research Laboratory, 325 Broadway, R/CSD6, Boulder, CO 80305, Watts, L A (laurel.a.watts@noaa.gov), NOAA Earth Systems Research Laboratory, 325 Broadway, R/CSD6, Boulder, CO 80305, Fahey, D W (david.w.fahey@noaa.gov), NOAA Earth Systems Research Laboratory, 325 Broadway, R/CSD6, Boulder, CO 80305, Richard, E C (erik.richard@lasp.colorado.edu), LASP, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303, Oltmans, S J (samuel.j.oltmans@noaa.gov), NOAA Earth Systems Research Laboratory, 325 Broadway, R/GMD, Boulder, CO 80305, Santee, M L (mls@mls.jpl.nasa.gov), Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Drive, Pasadena, CA 91109, Sen, B (Bhaswar.Sen@jpl.nasa.gov), Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Drive, Pasadena, CA 91109, Toon, G C (Geoffrey.C.Toon@jpl.nasa.gov), Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Drive, Pasadena, CA 91109,

Nitric acid is a primary reservoir species for reactive nitrogen and is a key player in ozone chemistry in the upper troposphere and lower stratosphere (UT/LS). An extensive in situ dataset of nitric acid and ozone measurements has been collected in the UT/LS between the equator and northern hemisphere midlatitudes with NOAA instruments onboard the NASA WB-57F high altitude research aircraft. These in situ data have been used to establish the robustness of nitric acid/ozone correlations in the lower stratosphere and the latitudinal variability in the correlation. These correlations are consistent with nitric acid/ozone correlations measured remotely at similar latitudes by the MkIV Interferometer and Aura MLS instruments. The utility of this correlation is demonstrated by establishing vertical profiles of proxy nitric acid mixing ratios using ozone data from the NOAA GMD ozonesonde network. These proxy profiles enhance the value of in situ nitric acid measurements in validating the Aura MLS instrument. Nitric acid/ozone correlations also provide a useful diagnostic for the redistribution of nitric acid in the UT/LS region by cloud sedimentation processes. The first in situ measurements of nitric acid in the tropical tropopause during Aura validation campaigns revealed extremely low nitric acid mixing ratios (<100 ppt) in this region. High-resolution in situ datasets continue to reveal information about the small- scale variability of nitric acid in the UT/LS that may not be available from remote instruments with large sampling volumes

A33H-03 

OMI Tropospheric NO2 from Lightning in Observed Convective Events

* Pickering, K E (Kenneth.E.Pickering@nasa.gov), NASA Goddard Space Flight Center, Laboratory for Atmospheres Code 613.3, Greenbelt, MD 20771, United States Bucsela, E (eric.bucsela@gsfc.nasa.gov), UMBC/GEST, NASA/GSFC, Code 613.3, Greenbelt, MD 20771, United States Kucsera, T L (tlk@croc.gsfc.nasa.gov), UMBC/GEST, NASA/GSFC, Code 613.3, Greenbelt, MD 20771, United States Pan, L (liwen@ucar.edu), National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, United States Davis, C (cdavis@ucar.edu), National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, United States Gleason, J (James.F.Gleason@nasa.gov), NASA Goddard Space Flight Center, Laboratory for Atmospheres Code 613.3, Greenbelt, MD 20771, United States Levelt, P (Pieternel.Levelt@knmi.nl), Royal Netherlands Meteorological Institute, Box 201, De Bilt, 3730 AE, Netherlands

Lightning is responsible for an estimated 15 percent of total NOx emissions, and is one of the most prominent sources in the upper troposphere. In this study, we present evidence of lightning-generated NO2 (LNO2) using data from the Ozone Monitoring Instrument (OMI), which has observed tropospheric NO2 since its launch in 2004. Although LNO2 has been also reported in previous satellite studies from the Global Ozone Monitoring Experiment (GOME) and SCIAMACHY, OMI is better suited for such measurements by virtue of its higher spatial resolution and daily global coverage. We will present data clearly showing the LNO2 signal in the OMI tropospheric NO2 product on two days over and downwind of specific convective systems in the US Midwest. Gridded monthly mean tropospheric NO2 data are subtracted from the daily gridded data to obtain the presumed LNO2 signal. Observed cloud-to-ground (CG) lightning flashes from the National Lightning Detection Network (NLDN) were counted along middle and upper tropospheric back trajectories that were run from the regions containing the LNO2 signal. A vertically-weighted average number of upwind CG flashes was obtained using a profile of LNOx mass obtained from a series of midlatitude cloud-resolved storm chemistry simulations. The number of CG flashes was scaled up to total flashes (intracloud (IC) flashes plus CG) using a climatological IC/CG ratio. The number of moles of LNOx in the region considered was estimated by assuming that LNO2 is 30 percent of LNOx. This value was divided by the number of upwind flashes to obtain an average estimate of the number of moles produced per flash. Results yield values in the range obtained through other estimation techniques (e.g., aircraft measurements, models). We will also present a similar analysis over northern Australia during the SCOUT-O3/ACTIVE field campaigns in November and December 2005, in which we will compare the OMI LNOx signals with aircraft observations from the storm anvils.

A33H-04 INVITED 

Stratospheric Transport Times From Observations and Models

* Hoor, P M (hoor@mpch-mainz.mpg.de), Max Planck Institute for Chemistry, Atmospheric Chemistry Department, J.J. Becherweg 27, Mainz, D-55128, Germany Lelieveld, J), Max Planck Institute for Chemistry, Atmospheric Chemistry Department, J.J. Becherweg 27, Mainz, D-55128, Germany Boenisch, H), Institute for Atmosphere and Environment, J.W.Goethe University, Altenhöferallee 1, Frankfurt/Main, D-60438, Germany Joeckel, P), Max Planck Institute for Chemistry, Atmospheric Chemistry Department, J.J. Becherweg 27, Mainz, D-55128, Germany Steil, B), Max Planck Institute for Chemistry, Atmospheric Chemistry Department, J.J. Becherweg 27, Mainz, D-55128, Germany Bruehl, C), Max Planck Institute for Chemistry, Atmospheric Chemistry Department, J.J. Becherweg 27, Mainz, D-55128, Germany Strahan, S), UMBC - Goddard Earth Science & Technology Center (GEST), NASA Goddard Space Flight Center, Greenbelt, MD 8080, United States

Transport time scales in the stratosphere are crucial to understand and calculate the effects of chemical active species on stratospheric chemistry. In general CO₂ or SF₆ have been used to calculate mean ages of air in the stratosphere, whereas shorter lived trace gases like CO are used to investigate cross tropopause transport and mixing on short time-scales close to the tropopause. Besides mean ages and their assocated mean trace gas mixing ratios at a given point in the atmosphere other quantities of the trace gas distributions can be used to constrain stratospheric transport times, such as variability and slope. In particular the younger part of the age spectrum needs to be constrained since it determines the extent to which shorter lived compounds can be transported into the stratosphere. We investigate transport times in the stratosphere based on observations of CO, N₂O and CO₂ and test a new approach to deduce transport times. For that purpose we compare observations from the ER-2 and other platforms. The approach is applied to global models (ECHAM5/MESSy, Combo GMI) to identify barriers as well as regions of rapid mixing and transport.

A33H-05 

Evaluation of Transport Characteristics and Chemical Composition in the UTLS region using a 3D Chemistry-Climate Model

* Kinnison, D E (dkin@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States Tilmes, S (tilmes@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States Pan, L (liwen@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States Schauffler, S (sues@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States Orlando, J (orlando@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States Garcia, R (rgarcia@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States Gettelman, A (andrew@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States Lamarque, J (lamar@ucar.edu

Brasseur, G (brasseur@ucar.edu), National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80503, United States

Three-dimensional coupled chemistry-climate models (CCMs) are currently being used to evaluate the evolution of stratospheric ozone throughout the 21st century (WMO/UNEP, 2007). Presently, little effort has been made to evaluate the chemical and dynamical performance of these CCMs in the upper troposphere and lower stratosphere (UTLS). Coupled models with tropospheric chemistry generally do not include resolve the dynamics of the UTLS, and models with appropriate stratospheric dynamics do not include a detailed representation of tropospheric chemical processes. In this study, we will use the Whole Atmosphere Community Climate Model (WACCM), a CCM developed at NCAR, to examine the impact on the UTLS of including a detailed representation of tropospheric chemical processes. We will contrast simulations from this version of WACCM with simulations that include only middle atmosphere chemical processes. The evaluation of both simulations will be compared with available in-situ tracer observations, specifically measurements obtained from several NASA high altitude aircraft field campaigns over North America.

A33H-06 

Recent evidences of deep convective transport through the tropopause

* Wang, P K (pao@windy.aos.wisc.edu), University of Wisconsin-Madison, 1225 W. Dayton Street, Madison, WI 53706, United States

A few years ago, we identified a deep convective transport mechanism (storm top gravity wave breaking) of water vapor through the tropopause so that tropospheric water substance can be injected into the lower stratosphere via this pathway. The main evidence we presented previously was taken from the lower resolution geostationary and a few polar orbiting satellite images of the storm anvil top cirrus plumes. Recent observations turn out more supporting evidences for this important vertical transport mechanism. There are now many higher resolution satellite images, mainly from MODIS instrument, that show more definitely the existence of these plumes, many of which would probably unseen by lower resolution GOES images. Furthermore, movies taken by a building top webcam also demonstrate that the jumping cirrus phenomenon, first identified by T. Fujita in 1980s, is quite common in active thunderstorm cells, quite contrary to previous belief that it is a rare occurrence. We have used a cloud model to demonstrate that the jumping cirrus is exactly the gravity wave breaking phenomenon that transports water vapor through the tropopause. Finally, the recent measurements of the heavy water to normal water ratio (HDO/H2O) clearly indicate that the ratio is much highly than that would be if the transport of water from the troposphere to the stratosphere is via slow ascent. The only explanation that can be used to interpret this observation is that water substance is transported through the tropopause via rapid vertical motion, i.e., deep convection. We will present satellite images, surface-based thunderstorm movies and the chemical measurements to demonstrate that the deep convective transport of water substance (and possibly other trace chemicals) through the tropopause is a very common phenomenon and may be one of the most importance pathways of vertical transport.

A33H-07 INVITED 

Dynamical variability of UTLS ozone and mixing near the extratropical tropopause from Atmospheric Infrared Sounder (AIRS) data

* Pan, L L (liwen@ucar.edu), National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305, Randel, W (randel@ucar.edu), National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305, Wei, J (Jennifer.Wei@noaa.gov), QSS Group Inc., 5201 Auth Rd., Camp Springs, MD 20746, Barnet, C (Chris.Barnet@noaa.gov), NOAA National Environmental Satellite Data and Information Service, 5201 Auth Rd., Camp Springs, MD 20746, Gettelman, A (andrew@ucar.edu), National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305, Hall, W (hallb@ucar.edu), National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305,

Understanding the role of dynamics in controlling the UTLS composition is a key element for predicting chemistry-climate interaction. Using newly available global ozone and water vapor data from AIRS on the NASA Aqua satellite, combined with meteorological data, we present an analysis of the dynamical variability of ozone in the UTLS region and the preferred locations of mixing across the tropopause. Key validation results and information content analyses will be discussed for both version 4 and version 5 retrieval. Our initial analyses, including comparisons with aircraft in situ and ozonesonde data, show that AIRS ozone profile data has ability to resolve synoptic-scale variability in the region of the extratropical tropopause, largely owing to its high horizontal resolution. In addition, AIRS collocated measurements of ozone and water vapor profiles in the UTLS region provide an opportunity to investigate the mixing between stratosphere and troposphere, using tracer-tracer correlations, on a global scale. Consistent with the conclusions of aircraft in situ data analyses, the preferred regions of mixing derived from AIRS data are on the cyclonic (poleward) side of the subtropical jet in association with the large separation of the thermal and dynamical tropopause.

A33H-08 

HIRDLS Observations of Strat-Trop Exchange in Thin Laminae in the Sub-Tropical Jet Region

* Gille, J (gille@ucar.edu), CLAS, University of Colorado, FL-0 3450 Mitchell Lane, Boulder, CO 80301, United States * Gille, J (gille@ucar.edu), NCAR, P.O. Box 3000, Boulder, CO 80307, Yudin, V (vyudin@ucar.edu), NCAR, P.O. Box 3000, Boulder, CO 80307, Nardi, B (nardi@ucar.edu), NCAR, P.O. Box 3000, Boulder, CO 80307, Phillips, T (phillitr@ucar.edu), CLAS, University of Colorado, FL-0 3450 Mitchell Lane, Boulder, CO 80301, United States Barnett, J (j.barnett1@physics.ox.ac.uk), Department of Atmospheric, Oceanic & Planetary Physics Oxford University Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom Khosravi, R (rashid@ucar.edu), NCAR, P.O. Box 3000, Boulder, CO 80307,

High Resolution Dynamics Limb Sounder (HIRDLS) data show atmospheric structures in the mid-latitude UT/LS region in which thin layers of low-latitude air having a low ozone mixing ratio move pole-ward over the subtropical jet stream during northern hemisphere winter, and simultaneously layers of mid-latitude air from the lowermost stratosphere, with higher ozone amounts move equator-ward beneath them. These layers appear to be too thin vertically to be seen by other instruments. The flows were observed between double tropopauses, at the time of a sudden stratospheric warming. This study extends the previous work to evaluate the frequency of such events as a function of time. Particular attention has been focused on the frequency, size, and effects of these structures at the end of the Northern Hemisphere winter, when more frequent tropopause fold events have been reported. Comparison to the overall dynamical situation shown by the GEOS-5 data reveals certain conditions in which these flows occur. The relationship of these structures to double tropopauses and the sub-tropical jet will be shown.

Author(s) (2007), Title, Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract #####-##.