Some structural features of a Bay of Bengal tropical cyclone

Abstract

The structure of the Bay of Bengal cyclone of 9 to 14 November 1984 could be studied, in detail thanks to simultaneous observations over a long period by coastal radars and the satellite INSAT-1B. The storm was small in size and had a small eye. It exhibited a double walled eye for some time. There was a highly, asymmetric distribution of radar reflectivity in the eyewall Corresponding asymmetries are inferred in the maximum wind and rainfall rate distribution in the core. The pressure gradient in the core exceeded 1 hPa/km. It was possible to delineate a radius of maximum radar reflectivity corresponding approximately to the radius of maximum winds. Such an estimation of radius of maximum winds will be, operationally useful in storm surge prediction. Changes In the radius of maximum reflectivity and the eyewall thickness seem to be correlated negatively with changes in cyclone intensity.

The rainfall distribution extended well to the northern side of the storm as expected, but also exhibited a maximum (with a steep sp3tial gradient) in the Madras-Sriharikota belt over a period of four days. After landfall the system persisted as a cyclone for several hours and developed a double-walled eye over land also.