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High humidities and subvisible cirrus near the tropical tropopause
Author(s) -
Jensen Eric J.,
Read William G.,
Mergenthaler John,
Sandor Brad J.,
Pfister Leonhard,
Tabazadeh Azadeh
Publication year - 1999
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 - 10.1029/1999gl900266
Subject(s) - cirrus , tropopause , troposphere , atmospheric sciences , water vapor , environmental science , radiative transfer , outgoing longwave radiation , atmosphere (unit) , humidity , radiative flux , relative humidity , stratosphere , longwave , microwave limb sounder , meteorology , geology , physics , convection , quantum mechanics
Measurements of water vapor from the Microwave Limb Sounder on the Upper Atmospheric Research Satellite show that humidities in the extreme tropical upper troposphere are often near saturation with respect to ice. These high humidity values are supported by the available accurate in situ water vapor measurements near the tropical tropopause. A nearly saturated upper troposphere reduces the outgoing longwave radiative flux at the top of the atmosphere by about 1–2 W‐m −2 compared to the radiative flux calculated using a standard atmospheric humidity profile. Subvisible cirrus near the tropopause reduce the outgoing longwave radiation an additional few W‐m −2 as well as increasing the radiative heating near the tropopause. Changes in the humidity frequency distribution in this region of the atmosphere and the associated changes in subvisible cirrus frequency would substantially impact the radiative budget of the tropics.