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E. Linacre and B. Geerts |
8/'98 |
There were marked changes in the atmospheric circulation in the southern hemisphere during the winter months of the 1970’s and 1980’s (1). Compared to earlier years, the sea-level pressure around Antarctica (50-60° S) was lower, the subantarctic trough shifted equatorward, the sea-level pressure at low latitudes (20-30° S) increased, and the subtropical highs shifted slightly poleward.
As a result, the meridional pressure gradient and wind speed in mid-latitudes increased, and frontal disturbances moved more rapidly from west to east. Not surprisingly, the 1970’s and 1980’s were wetter than previous years, especially between 30-50° S.
Reference
(1) van Loon, H., J.W. Kidson and A.B. Mullen 1993. Decadal variaton of the annual cycle in the Australian data sets. J. Clim. 6, 1227-31.