E. Linacre and B. Geerts
There were marked changes in the atmospheric circulation in the southern hemisphere during the winter months of the 1970ís and 1980ís (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 1970ís and 1980ís were wetter than previous years, especially between 30-50° S.
(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.