NOAA TOVS-DERIVED MOISTURE FIELDS OVER THE ARABIAN SEA AND THE BAY OFBENGAL AND THEIR ASSOCIATION WITH THE SOUTH-SEST MONSOON

Moisture fields derived from the Tiros-N Operational Vertical Sounder (TOVS) data onboard previous National Oceanic and Atmospheric Administ ration (NOAA) series of satellites have been used to study monthly moi sture fields over the Arabian Sea and the Bay of Bengal for the years 1979-1981. It is observed that monthly averaged moisture fields over t he Bay of Bengal are always more than those over the Arabian Sea at a given latitudinal belt. Further, the monthly mean moisture flux diverg ence has been calculated using monthly mean winds from ship observatio ns over the same areas of the Arabian Sea and the Bay of Bengal. It is found that net moisture flux divergence over the Arabian Sea is consi stently higher than that over the Bay of Bengal for the years, 1979, 1 980, and 1981, which are deficient, and excess monsoon rainfall years in terms of departure from long-term climatological rainfall values. M oisture variability over the Arabian Sea and the Bay of Bengal on a mo nthly scale has also been studied for the months of June, July, and Au gust for the years 1979-1981. A plot of the zonally averaged (at every 2 degrees latitude) differential moisture signal (DMS) by latitude in dicates the approximate position of the low-level westerly jet. The ov erall differential signal between zonally averaged moisture fields ove r the Arabian Sea and the Bay of Bengal has also been found to be an i ndicator of total Indian rainfall, excluding orographically influenced regions, although more data is needed to firmly establish the relatio nship quantitatively.