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Temperature dependence of atmospheric moisture lifetime
Author(s) -
Kennett E. J.,
Toumi R.
Publication year - 2005
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 - 10.1029/2005gl023936
Subject(s) - cirrus , moisture , water vapor , atmospheric sciences , environmental science , relative humidity , humidity , nucleation , climatology , meteorology , thermodynamics , geology , physics
In this study, the temperature dependence of atmospheric moisture lifetime is investigated using the European Centre for Medium‐Range Weather Forecasts 40‐year Reanalysis (ERA40) dataset. ERA40 shows that atmospheric moisture lifetimes can vary by greater than a factor of 4 within the column. Globally, the shortest lifetimes occur at temperatures of about −40°C, with mean lifetimes of just over a day at this level. Lifetimes derived independently from aircraft microphysical measurements in cirrus clouds confirm the rapid loss of moisture at about −40°C. This can be understood to result from changes in the rate of nucleation and size distribution of ice particles with decreasing temperature. A similar temperature dependence is observed in water vapor scale height, with relative humidity increasing with decreasing temperature below about −40°C. The variability of atmospheric moisture lifetime with temperature is found to be a fundamental microphysical control on the distribution of water vapor.