A MONSOON DEPRESSION OVER NORTHWESTERN AUSTRALIA PART-I - CASE-STUDY

A diagnostic study of a monsoon depression that developed over northwe stern Australia in February 1994 is presented. The analyses are based on gridded data from the Australian Bureau of Meteorology's Tropical A nalysis System. After remaining quasi-stationary for several days afte r its formation in the monsoon trough, the depression drifted slowly s outhwestwards along the coast of Western Australia and eventually weak ened. The evolution is exemplified by time-height cross-sections of va rious kinematic quantities as well as the apparent sources of heat, mo isture and potential vorticity, A prominent feature of these diagnosti c fields is the impact of convective and diabatic processes on the dev elopment. The structure of the depression was very similar to the few monsoon depressions that have been documented over the Indian subconti nent, The formation of the depression coincided with the passage of an upper-level mid-latitude trough and a low-level anticyclone to the so uth, but the extent to which the genesis was influenced by these distu rbances is unclear.