Distribution and intraseasonal variability of rain over Indian Oceanic region from Indian Remote Sensing Satellite IRS‐P4 Multifrequency Scanning Microwave Radiometer

Abstract

Multifrequency Scanning Microwave Radiometer (MSMR) onboard Indian Remote Sensing Satellite (IRS‐P4) has been utilized for measurement of precipitation over Indian Oceanic region. MSMR‐derived monthly rain rates for the month of August for three consecutive years are compared with that from TMI and PR. A reasonably good agreement is found. Rain distributions are presented for three seasons, namely, premonsoon (February–May), monsoon (June–September), and postmonsoon (October–January) for the entire period of MSMR from June 1999 to September 2001. The year‐to‐year difference in the three seasons is found in agreement with the weather reports. Latitudinal distribution of the MSMR‐derived rain rate for the Arabian Sea and the Bay of Bengal and for the entire study area are analyzed and are found to be in good agreement with climatology. Furthermore, starting from 60°E longitude up to 95°E, at every 5° interval, latitudinal distribution of rain rate is plotted for the three monsoon seasons. It is found that the vigor of monsoon rain begins building up between 65° and 70°E and goes beyond 95°E. A time series and wavelet analysis of daily rain rate is presented for monsoon seasons of three consecutive years. Wavelet analysis clearly shows the presence of long waves of 30–60 and 10–20 day oscillations and also of synoptic scale of 3–6 day oscillations in the monsoon rain. Furthermore, Hovmoller diagrams of daily rain over the northern Bay of Bengal are analyzed for monsoon seasons of three years, and some northward propagation of rain is reported.