1 WATER VAPOR WINDS FROM KALPANA VHRR: A NEW APPROACH

The information of tropospheric wind is extremely necessary for numerical weather prediction. A significant contribution of upper air wind information is derived from satellite observations that use the movement of cloud and water vapor tracers to determine winds operationally several times a day. The use of geo-stationary water vapor imagery has allowed the determination of both upper-level moisture content and the wind fields that correspond to the water vapor layers. Water vapor images from geostationary satellite allow the determination of winds in cloud-free regions also. The main aim of this study is to derive upper tropospheric winds operationally from the observations from Indian geostationary satellites. With the availability of water vapor channel (6.3 –7.1 m) on-board KALPANA VHRR; the first attempt has been made in India to derive water vapor winds (500-100 hPa) from Indian geo-stationary satellites. The algorithms of water vapor wind retrieval techniques basically depend upon the proper selection of appropriate water vapor tracers that are generally in the locations of maximum bidirectional gradients in the image and corresponding tracking of these tracers in the subsequent image. In the present work, upper-level atmospheric motion is derived from the water vapor images by considering 1) fast and efficient tracer selection procedure based on local image anomaly, 2) tracking procedure of the selected tracer in th