A13C-0354
A comparison of ATTREX H2O observations in the TTL with values derived from reanalysis-based back trajectories

Monday, 14 December 2015
Poster Hall (Moscone South)
Troy D Thornberry1, Andrew W Rollins1, Thaopaul V Bui2, Leonhard Pfister2 and Ru-Shan Gao1, (1)NOAA Boulder, Boulder, CO, United States, (2)NASA Ames Research Center, Moffett Field, CA, United States
Abstract:
Despite very low mixing ratios relative to the troposphere, water vapor in the lower stratosphere (LS) plays a significant role in Earth’s radiative balance and climate system, and is an important constituent in stratospheric chemistry. The low H2O content of air entering the LS is established to first order by dehydration processes controlled by the cold temperatures of the tropical tropopause layer (TTL), especially over the western Pacific. Global climate models rely on parameterizations in order to simulate TTL dehydration processes and calculate the amount of H2O transported into the stratosphere. Here we present an analysis of in situ water vapor measurements in the western Pacific TTL from the NASA ATTREX campaign and compare them to reanalysis-based back trajectory calculations of LS H2O in order to investigate the efficiency of TTL dehydration processes and provide constraints on the representation of TTL dehydration in reanalyses and global models.