Satellite observations of the southern hemisphere monsoon during Winter MONEX

Abstract

Time–longitude strips of infrared GMS satellite imagery have been used to study the southern hemisphere summer monsoon during Winter MONEX. This representation reveals a sudden monsoon onset in late December characterized by a transition to spatially organized convection. Active and break regions of the monsoon show a strong coherence in time but are very longitudinally dependent. The latitudinal dependence, on the other hand, is quite weak. The dominant spatial scale over which changes in convection take place is of order 35 degrees longitude by 15 degrees latitude. These synoptic scale convective regions can move in either the eastward or westward direction. Typical phase speeds of movement range between 3 and 8 degrees longitude per day. Tropical cyclones in the region are revealed to be embedded in the large-scale monsoon circulation.