The Circulation Response to Idealized Changes in Stratospheric Water Vapor

Maycock, Amanda C., Joshi, Manoj M., Shine, Keith P. and Scaife, Adam A. (2013) The Circulation Response to Idealized Changes in Stratospheric Water Vapor. Journal of Climate, 26 (2). pp. 545-561. ISSN 0894-8755

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Abstract

Observations show that stratospheric water vapor (SWV) concentrations increased by ~30% between 1980 and 2000. SWV has also been projected to increase by up to a factor of 2 over the twenty-first century. Trends in SWV impact stratospheric temperatures, which may lead to changes in the stratospheric circulation. Perturbations in temperature and wind in the stratosphere have been shown to influence the extratropical tropospheric circulation. This study investigates the response to a uniform doubling in SWV from 3 to 6 ppmv in a comprehensive stratosphere-resolving atmospheric GCM. The increase in SWV causes stratospheric cooling with a maximum amplitude of 5–6 K in the polar lower stratosphere and 2–3 K in the tropical lower stratosphere. The zonal wind on the upper flanks of the subtropical jets is more westerly by up to ~5 m s-1. Changes in resolved wave drag in the stratosphere result in an increase in the strength of tropical upwelling associated with the Brewer–Dobson circulation of ~10% throughout the year. In the troposphere, the increase in SWV causes significant meridional dipole changes in the midlatitude zonal-mean zonal wind of up to 2.8 m s-1 at 850 hPa, which are largest in boreal winter in both hemispheres. This suggests a more poleward storm track under uniformly increased stratospheric water vapor. The circulation changes in both the stratosphere and troposphere are almost entirely due to the increase in SWV at pressures greater than 50 hPa. The results show that long-term trends in SWV may impact stratospheric temperatures and wind, the strength of the Brewer–Dobson circulation, and extratropical surface climate.

Item Type: Article
Uncontrolled Keywords: annular mode,transport,stratospheric circulation,statophere-troposphere coupling,water vapor
Faculty \ School: Faculty of Science > School of Environmental Sciences
Related URLs:
Depositing User: Pure Connector
Date Deposited: 05 Nov 2013 17:00
Last Modified: 18 Oct 2018 11:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/44237
DOI: 10.1175/JCLI-D-12-00155.1

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