The annual cycle of stratospheric water vapor in a general circulation model

Journal Article · Thu Apr 20 04:00:00 EDT 1995 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JD03301· OSTI ID:166244

Mote, P W ^[1]

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1. Univ. of Washington, Seattle, WA (United States)

The application of general circulation models (GCMs) to stratospheric chemistry and transport both permits and requires a thorough investigation of stratospheric water vapor. The National Center for Atmospheric Research has redesigned its GCM, the Community Climate Model (CCM2), to enable studies of the chemistry and transport of tracers including water vapor; the importance of water vapor to the climate and chemistry of the stratosphere requires that it be better understood in the atmosphere and well represented in the model. In this study, methane is carried as a tracer and converted to water; this simple chemistry provides an adequate representation of the upper stratospheric water vapor source. The cold temperature bias in the winter polar stratosphere, which the CCM2 shares with other GCMs, produces excessive dehydration in the southern hemisphere, but this dry bias an be ameliorated by setting a minimum vapor pressure. The CCM2`s water vapor distribution and seasonality compare favorably with observations in many respects, though seasonal variations including the upper stratospheric semiannual oscillation are generally too small. Southern polar dehydration affects midlatitude water vapor mixing ratios by a few tenths of a part per million, mostly after the demise of the vortex. The annual cycle of water vapor in the tropical and northern midlatitude lower stratosphere is dominated by drying at the tropical tropopause. Water vapor has a longer adjustment time than methane and had not reached equilibrium at the end of the 9 years simulated here. 57 refs., 17 figs., 1 tab.

• OSTI ID: 166244
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: D4 Vol. 100; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ANNUAL VARIATIONS
ECOLOGICAL CONCENTRATION
GENERAL CIRCULATION MODELS
GLOBAL ASPECTS
STRATOSPHERE
WATER VAPOR