AN OPERATIONAL STATUS AND VALIDATION OF CLOUD MOTION VECTORS WITH IMPROVEMENT IN WATER VAPOR WINDS DERIVED FROM KALPANA-1 SATELLITE AT IMD

The Cloud Motion Vector (CMV) is one of important meteorological products derived from satellite data and is known that it has a positive or neutral impact on global or middle scale numerical forecast results. Currently, CMV at India Meteorological Department, New Delhi , is being operationally generated using infrared (IR) data from Kalpana-1 satellite since April 2003. In the quality check procedure of the derivation technique, the output of the Limited Area Model (LAM) forecast data , which covers the area 40E-129E and 29S-45N, produced operationally in IMD, has been preferred over climatology. These CMVs are put on GTS for end users in both SATOB as well as BUFR format. The error analysis has been carried out for the validation of CMV with the available LAM forecast and Meteosat-5 winds. The comparison shows that the quality of Kalpana-1 CMVs compares well with the LAM forecast. The error statistics of these observations and its improvement using neural network (NN) technique is also presented. The result indicates that the pattern of NNCMV (ANN model output CMV) is much closer to the Meteosat derived winds. The vital changes have also been incorporated in the Kalpana-1 CMVs and WVWs derivation. The changes include improved hight assignment technique using H2O interception method,better navigation and use of LAM forecast field in quality controls. As a result of these changes the quality of Kalpana-1 derived WVW has improved. Further, Kalpana-1 derived water vapor winds (WVW) have also been compared with the available mid-upper level winds derived from Meteosat-7 as a part of validation. A case study of a 'sidr' cyclone has examined and it has found that the Kalpana-1 derived WVW has shown fairly good agreement with the Meteosat-7 winds.