Tropical cyclone Dera, the unusual 2000/01 tropical cyclone season in the South West Indian Ocean and associated rainfall anomalies over Southern Africa |
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| Authors: | C J C Reason |
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| Institution: | (1) Department of Oceanography, University of Cape Town, Rondebosch, South Africa |
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| Abstract: | Summary Austral summer 2000/01 in the southern African region was unusual in several respects. Tropical cyclone activity in the southwest
Indian Ocean was substantially less than average despite large areas of this region showing anomalously warm sea surface temperatures
(SST) for much of the season. Many areas of southern Africa experienced above average rainfall with local flooding in parts
of Mozambique. In the tropical southeast Atlantic, a large warm SST anomaly evolved off the coast of Angola and northern Namibia
in late summer suggesting a Benguela Ni?o event. During the late summer (February–April 2001), three particularly widespread
and intense wet spells occurred over tropical southern Africa, one of which coincided with tropical cyclone Dera.
This study considers the generation and evolution of the middle wet spell of late summer 2001 and its relationship with tropical
cyclone Dera. This storm was generated in the northwestern part of the Mozambique Channel and then tracked more or less due
south through the Channel and into the subtropical southwest Indian Ocean. Rainfall associated with Dera contributed to the
ongoing floods over central Mozambique that arose from rains earlier in the season. Dera occurred in early March following
a relatively long period of no tropical cyclone activity in the southwest Indian Ocean. A build up of favorable conditions
during the preceding weeks contributed towards the storm whereas an anticyclonic anomaly east of Madagascar led to the northerly
steering current and the southward track of tropical cyclone Dera out of the Mozambique Channel. |
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