HR: 0800h
AN: A41B-0037    [Abstracts]
TI: Mechanisms controlling the humidity of the Tropical Tropopause Layer over the Eastern Tropical Pacific
AU: * Pittman, J V
EM: pittman@usra.edu
AF: University Space Research Association, Global Hydrology and Climate Center, 320 Sparkman Drive, Huntsville, AL 35805 United States
AU: Fueglistaler, S
EM: stefan@atmos.washington.edu
AF: Dept. of Atmospheric Sciences, University of Washington, 316 ATG Building Box 351640, Seattle, WA 98195 United States
AU: Miller, T L
EM: Tim.Miller@nasa.gov
AF: NASA Marshall Space Flight Center, Global Hydrology and Climate Center, 320 Sparkman Drive, Huntsville, AL 35805 United States
AU: Weinstock, E M
EM: weinstock@huarp.harvard.edu
AF: Dept. of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138 United States
AB: Aircraft measurements obtained aboard NASA's WB-57 and backward trajectory calculations are used to explore the mechanisms that control the humidity of the Tropical Tropopause Layer (TTL) over the Eastern Tropical Pacific. Of particular interest are the mechanisms that set the entry value of water vapor into the tropical stratosphere. In-situ data are obtained from the Clouds and Water Vapor in the Climate System (CWVCS) and the Pre-Aura Validation Experiment (Pre-AVE) campaigns both based out of San Jose, Costa Rica in August 2001 and January 2004, respectively. Analysis of in situ measurements of water vapor and temperature show frequent undersaturated conditions in the TTL region during both seasons suggesting that the entry value of stratospheric water vapor is not set by local saturation conditions. Furthermore, radiosonde data show minimum saturation mixing ratios over the Western Tropical Pacific as well as zonally averaged over the entire tropics (15S - 15N) to be 0.3 to 1.5 ppmv lower than the aircraft measurements. Trajectory calculations driven by ECMWF wind fields are used to explore the Lagrangian temperature history of the sampled air parcels along with their geographical origin in order to elucidate the effect that horizontal transport through cold pools might have on the humidity of the region.
DE: 0340 Middle atmosphere: composition and chemistry
DE: 0341 Middle atmosphere: constituent transport and chemistry (3334)
DE: 3362 Stratosphere/troposphere interactions
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005