HR: 16:30h
AN: A44C-03    [Abstracts]
TI: TES Observations of the Isotopic composition of Tropospheric Water Vapor
AU: * Worden, J R
EM: john.worden@jpl.nasa.gov
AF: JPL / Caltech, 4800 Oak Grove Drive, Pasadena, CA 91101
AU: Bowman, K
EM: kevin.bowman@jpl.nasa.gov
AF: JPL / Caltech, 4800 Oak Grove Drive, Pasadena, CA 91101
AU: Noone, D
EM: dcn@colorado.edu
AF: PAOS/CIRES, U. of Colorado, Boulder, CO 80309
AB: The isotopic composition of atmospheric water vapor is sensitive to the history of condensation and evaporation processes. We present new global observations of the isotopic composition of tropospheric water vapor, namely HDO along with H2O, from the Tropospheric Emission Spectrometer aboard the NASA Aura spacecraft. The sensitivity of the retrieval of HDO/H2O is typically largest between 850 hPa and 400 hPa with a peak sensitivity at 700 hPa. An average of the HDO/H2O profile over these pressures has a precision of 1.5% or about 15 parts per thousand (per mille) relative to Standard Mean Ocean Water. This precision is sufficient for characterizing the global distribution of evaporation and condensation processes. The data show greater depletion toward the polar regions and is characteristic of preferential removal of heavy nuclides during condensation as water vapor moves pole-ward. These observations are consistent with in situ measurements of the isotopic composition of precipitation, which also shows a pole-ward depletion. We also find that the HDO/H2O ratio over tropical land regions can be enhanced relative to ocean values indicating strong convection (both wet and dry) and evapo-transpiration. Isotopic arguments that compare the HDO/H2O ratio to H2O show that most of the global tropospheric water distribution can be explained by a balance between condensation and evaporation from extra-tropical oceanic sources. The tendency of these distributions around some mean specific humidity and isotopic composition provides a quantification of the residence time of atmospheric water - one metric of the intensity of the hydrologic cycle. This distribution points towards the estimation of evaporation source locations and an assessment of the range of global cloud processes.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere: composition and chemistry
DE: 1655 Water cycles (1836)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005