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Observational constraints on the efficiency of dehydration mechanisms in the tropical tropopause layer
Author(s) -
Rollins A. W.,
Thornberry T. D.,
Gao R. S.,
Woods S.,
Lawson R. P.,
Bui T. P.,
Jensen E. J.,
Fahey D. W.
Publication year - 2016
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 - 10.1002/2016gl067972
Subject(s) - tropopause , stratosphere , dehydration , atmospheric sciences , water vapor , environmental science , saturation (graph theory) , relative humidity , climatology , meteorology , physics , chemistry , geology , mathematics , biochemistry , combinatorics
The efficiency of dehydration in the tropical tropopause layer (TTL) determines how closely water vapor will be reduced to the lowest saturation mixing ratio encountered along a trajectory to the stratosphere, thereby strongly influencing stratospheric humidity. The NASA Airborne Tropical Tropopause Experiment (ATTREX) provided an unprecedented number and quality of in situ observations to constrain the key mechanisms controlling this dehydration. Statistical analyses of the ATTREX data show that nucleation, growth, and sedimentation each result in TTL dehydration becoming increasingly inefficient at temperatures below 200 K. Because of these inefficiencies, models that ignore these mechanisms likely underestimate water vapor at the stratospheric entry point by ~10–20% at the lowest temperatures.