Open AccessVariability in HDO/H 2 O abundance ratios in the tropical tropopause layer
Author(s) -
Nassar Ray,
Bernath Peter F.,
Boone Chris D.,
Gettelman Andrew,
McLeod Sean D.,
Rinsland Curtis P.
Publication year - 2007
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007jd008417
Subject(s) - troposphere , water vapor , atmospheric sciences , tropopause , stratosphere , environmental science , climatology , southern hemisphere , tropics , convection , meteorology , geology , physics , biology , fishery
The dehydration of air in the tropical tropopause layer (TTL) and mechanisms for the entry of water vapor into the stratosphere are investigated by an analysis of ACE‐FTS profiles of temperature, water vapor, and the ratio [HDO]/[H 2 O] expressed in δ D notation. Month‐to‐month comparisons indicate greater seasonal variability than interannual variability between 25°S–25°N, thus comparisons are made between February, April, August, and October averages for the years 2004 and 2005 combined. The data indicate a pattern of seasonal variability which is clearer in the Northern Hemisphere tropics and a relationship between minimum temperature, minimum water vapor, and maximum HDO depletion, which exists beyond the estimated uncertainty in these values. The range of values observed for HDO depletion and comparisons to modeled Rayleigh distillation curves indicate an important contribution from convection in addition to gradual dehydration. Multiple factors including the shape of the δ D profiles suggest that a likely mechanism for the convective influence is the lofting of ice particles in the tropical troposphere.