Open AccessStratospheric and mesospheric latitudinal water vapor distributions obtained by an airborne millimeter‐wave spectrometer
Author(s) -
Peter R.
Publication year - 1998
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 - 10.1029/98jd00968
Subject(s) - atmospheric sciences , water vapor , stratosphere , polar vortex , mixing ratio , environmental science , mesosphere , subtropics , latitude , altitude (triangle) , physics , meteorology , geometry , mathematics , astronomy , fishery , biology
In the last 3 years, several flights from polar regions (Spitzbergen, 78°N) to the subtropics (Cap Verde Islands, 16°N) have been performed with the Airborne Millimeter‐ and Submillimeter‐Wave Observing System aboard a Learjet of the Swiss Air Force. From the observation of the H 2 O rotational transition at 183.31 GHz, altitude‐latitude cross sections of the middle atmospheric water vapor abundance for August 1994, October 1995, and March 1996 have been derived from the subtropical to Arctic regions. The key findings in this new H 2 O data set of the latitudinal variation from the lower stratosphere to the mesosphere are (1) the unusually high H 2 O abundance of 6.8 ppm at a potential temperature of 700 K in the spring 1996 polar vortex indicating a strong downward descent of ∼14 km from October to March associated with air mass isolation, (2) the seasonal dependent modulations of the dry subtropical stratospheric H 2 O profile, (3) flat volume mixing ratio (VMR) contours between 35° and 65°N due to isentropic mixing, (4) a maximum H 2 O VMR of more than 7.5 ppm in the subtropical mesosphere suggesting a disturbed mesospheric hydrogen partitioning possibly due to an enhanced conversion of methane and molecular hydrogen to water vapor, and (5) a general increase of middle atmospheric water vapor VMR of ∼1.5 ppm since 1986.