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Role of deep convection in establishing the isotopic composition of water vapor in the tropical transition layer
Author(s) -
Smith Jamison A.,
Ackerman Andrew S.,
Jensen Eric J.,
Toon Owen B.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl024078
Subject(s) - water vapor , convection , atmospheric sciences , cirrus , environmental science , mixing ratio , deep convection , diabatic , climatology , geology , meteorology , thermodynamics , physics , adiabatic process
The transport of H 2 O and HDO within deep convection is investigated with 3‐D large eddy simulations (LES) using bin microphysics. The lofting and sublimation of HDO‐rich ice invalidate the Rayleigh fractionation model of isotopologue distribution within deep convection. Bootstrapping the correlation of the ratio of HDO to H 2 O (δD) to water vapor mixing ratio (q v ) through a sequence of convective events produces non‐Rayleigh correlations resembling observations. These results support two mechanisms for stratospheric entry. Deep convection can inject air with water vapor of stratospheric character directly into the tropical transition layer (TTL). Alternatively, moister air detraining from convection may be dehydrated via cirrus formation in the TTL to produce stratospheric water vapor. Significant production of subsaturated air in the TTL via convective dehydration is not observed in these simulations, nor is it necessary to resolve the stratospheric isotope paradox.