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Summer regional rainfall over southern Ontario and its associations with outgoing longwave radiation and moisture convergence

Published online by Cambridge University Press:  01 July 2005

Zhenhao Bao
Affiliation:
Department of Earth and Atmosphere Science, York University, 4700 Keele Street, Toronto Ont., M3J 1P3 Canada Climate Research Branch, Meteorological Service of Canada, 4905 Dufferin Street, Downsview, Ontario, M3H 5T4 Canada
Hengchun Ye
Affiliation:
Department of Geography and Urban Analysis, California State University, Los Angeles, California 90032-8222, USA Email: Hye2@calstatela.edu
Peter A. Taylor
Affiliation:
Department of Earth and Atmosphere Science, York University, 4700 Keele Street, Toronto Ont., M3J 1P3 Canada
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Abstract

Daily rainfall records at 50 sites across southern Ontario are used to investigate the association of summer regional rainfall with outgoing longwave radiation (OLR) and moisture convergence, from 1991 to 2000. The results suggest that OLR values correspond well to heavy rainfall amounts when rain occurs over more than 90% of the study region. The average regional daily precipitation of 12.1 mm/day corresponds to 213.0 W/m2 of OLR values in the study region. Also, OLR is more significantly associated with the regional daily rainfall amount than moisture convergence in the atmospheric layers between 1000 hPa and 300 hPa although both are associated with precipitation. The study suggests that when a low OLR departure centres over Ontario, the region tends to have extremely heavy rainfall and flooding. The results of this study indicate that OLR is a useful tool for satellite detection of extremely heavy rainfall and possible flash flooding during the summer season over southern Ontario.

Type
Research Article
Copyright
© 2005 Royal Meteorological Society

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