Seasonal Variation and Environmental Properties of Southward Propagating Mesoscale Convective Systems over the Bay of Bengal
2006 Volume 2 Pages 88-91
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2006 Volume 2 Pages 88-91
We tracked fast moving mesoscale convective systems (MCSs) over the Bay of Bengal, counted their numbers, and analyzed the characteristics of wind and geopotential fields of when such MCSs propagate southward over the Bay. We used hourly TBB data of GMS5 IR1 (1996-2001, April-October) for the tracking, and used 6-hourly ECMWF 40 year re-analysis data to analyze the characteristics of wind and geopotential fields.
The numbers of fast moving MCSs were as follows: April 11/56 (20%); May 46/103 (45%); June 50/173 (29%); July 33/160 (21%); August 27/125 (22%); September 8/61 (13%); October 8/67 (12%); total 183/745 (25%). The fractions represent (number of southward propagating MCSs)/(total number of MCSs), and the numbers inside the parentheses are the percentages of the southward propagating MCSs.
We concluded that fast southward propagation of MCSs tends to occur when a trough exists over the Bay at the height of 600 hPa, and the wind shear between the surface and the 600 hPa height has a southward component. We also found that propagation towards other directions is related with eddy disturbances over the Bay.
