Integrated satellite microwave and infrared measurements of precipitation during a Bay of Bengal cyclone

Abstract

In the present paper, an approach for integrated IR and microwave measurements using various satellite sensors have been used for the study of a severe cyclone over Bay of Bengal and adjoining Eastern India and Bangladesh during 24-29 April 1991. The rain estimates from measurements of brightness temperatures from Special Sensor Microwave/Imager

(SSM/I) and Outgoing Longwave Radiation (OLR) from IR radiances of polar orbiting and geostationary satellites have been used. Since the OLR derived rainfall exhibit a larger spatial spread with lower intensities in rain fall fields, we have followed the above procedure for optimally combining both the observations for more realistic rainfall o n regional scale to

study precipitation fields. Since the OLR rains are well represented spatially and tempo rally by more frequent observations from both geostationary and polar orbiting satellites, the algorithm sharpens the IR derived rain s and augments it to the microwave derived rain. The combined IR and microwave rain algorithm brings out the finer details of the cyclone structure and precipitation fields, and thus seems to be highly promising for operational applications. Some aspects of the associated wind fields are also examined for their relationship with tropical rain intensity in the present case. A comparison of rainfall is performed with rare <i>in-situ </i>observations over the coastal regions during the severe cyclone.