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Water vapor enhancement in the polar summer mesosphere and its relationship to polar mesospheric clouds
Author(s) -
Hervig Mark,
McHugh Marty,
Summers Michael E.
Publication year - 2003
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 - 10.1029/2003gl018089
Subject(s) - mesopause , atmospheric sciences , mesosphere , water vapor , occultation , polar , environmental science , mixing ratio , evaporation , altitude (triangle) , upwelling , polar night , climatology , meteorology , geology , physics , stratosphere , oceanography , astronomy , geometry , mathematics
Polar mesospheric water vapor exhibits a strong seasonal cycle, with summer mixing ratios dramatically higher than in winter. It is generally accepted that vertical transport from ∼50 km altitude towards the mesopause is one driver behind this change, however, upwelling alone cannot explain observed H 2 O changes. H 2 O near 83 km increases from 1 ppmv in winter to over 8 ppmv in summer, and upwelling accounts for roughly half of this increase. It has been suggested that evaporation of polar mesospheric clouds (PMCs) should produce a layer of enhanced water vapor. This idea was explored using particle measurements from the Halogen Occultation Experiment (HALOE) to derive the equivalent gas phase H 2 O contained in PMCs. Comparing these estimates to HALOE water vapor measurements suggests that PMC evaporation is a large component in H 2 O enhancement near 83 km during summer.