RIS ID
11955
Abstract
Mobile Polar Highs (MPHs) are masses of cold air that move out aperiodically from the Antarctic Icecap and eventually cross Australia. Their movement from the Weddell Sea and the Lambert Glacier was monitored between 26 March and 20 July 2004 using daily satellite images and synoptic charts. Their leading edge appears on these images as a distinct arced cloudband. The patterns of MPHs were then linked to significant rainfall events—>50 mm in 24 hrs—in southeastern Australia. Although most of this area of Australia was in drought over the study period, three major rainfall events resulted from the passage of three of the eleven MPH events mapped. All three events either originated or received cold air injections from the Lambert Glacier. Analysis of MPHs between January and March 2000 also indicated that polar air originating from this latter location could be linked to major rainfall events over southeastern Australia. If this relationship holds over time, then the tracking of MPHs offers a prognosis by several days for heavy rainfalls in southeastern Australia. MPHs appear to be another dynamic element of southern hemisphere circulation influencing the rainfall of southern Australia.
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Publication Details
This chapter was originally published as: Hargraves, C & Bryant, EA, Mobile polar highs over Australia : origins and effect on rainfall, in R.J. Morrison, S. Quin and E.A. Bryant (eds.), Planning for Natural Hazards — How Can We Mitigate the Impacts?, GeoQuEST Research Centre, University of Wollongong, 2005, 167-175.