ESTIMATION OF LARGE SCALE WIND FIELDS OVER OCEANIC AREAS AROUND INDIA USING INSAT DERIVED CLOUD MOTION VECTORS IN CONJUNCTION WITH SHIP/BUOY DATA AND SCATTEROMETER DATA R.C. BHATIA AND K.C. SAI KRISHNAN Office of Deputy Director General of Meteorology (Upper Air Instruments) India Meteorological Department Lodi Road, New Delhi-110003 India ABSTRACT The low-level Cloud Motion Vectors (CMVs) derived from INSAT data are useful for estimating sea surface wind and ultimately wind stress over the large oceanic areas within reasonable limits of accuracy. CMVs are compared to ship/buoy observations collected over the oceans and the results indicate that low-level CMVS could be used to estimate surface winds to an r.m.s. accuracy of about 3m/sec in speed and about 30 degree in direction or even better, depending upon wind speed. The auto-correlation coefficients were also calculated to evaluate the consistency in CMVs and the ship data. These results are based on the limited comparison done using the available scatterometer data over the common coverage areas. Study shows the feasibility of estimating large scale wind field over the data sparse oceanic regions using all three data sets i.e. CMVs, ship/buoy and scatterometer. Such type of data sets have potential application for better analysis of synoptic charts during the summer monsoon season which is very important for routine operations. 1. INTRODUCTION A few improvements have been carried out over the last few years to the INSAT derived Cloud Motion Vectors (CMVs). These have been discussed at length in several papers (Bhatia et al, 1996, Kelkar et al 1993, Khanna et al, 1998 and