Synoptic influences on seasonal, interannual and decadal temperature variations in Melbourne, Australia

摘要

The technique of self-organizing maps (SOMs) has been applied to daily mean sea level pressure (MSLP) reanalyses to derive 20 large-scale synoptic patterns in the Australian region. The frequency of occurrence of each of these synoptic patterns has been calculated for each 3-month season from 1979 to 2001. The effect of variations in the relative frequency of these synoptic patterns on maximum daily temperature in Melbourne, in the southeast of the country, has been examined. The effects of frequency variations on the mean summer-winter temperature difference, on the variations in mean temperature from year-to-year and on the temperature trend 1979-2001 have all been examined. Changes in the frequency of occurrence of synoptic patterns between seasons have a measurable influence on the mean summer-winter temperature difference. Variations in winter temperatures from year-to-year are closely related to the frequency of a few synoptic patterns, and changes in the frequency of these patterns have contributed to the observed temperature trends. Relationships between temperature and the frequency of synoptic patterns in summer are weaker than the case for winter. The implications are discussed.