AN ALGORITHM TO OVERLAY CONTINENTAL BOUNDARIES AND LATITUDE-LONGITUDEGRIDS OVER INSAT-VHRR IMAGES

The VHRR imagers aboard geostationary satellites have been the major s ource of quasicontinuous meteorological weather monitoring over tropic al and subtropical latitudes. Accurate geolocation of pixels with resp ect to continental boundaries in digital VHRR images, irrespective of problems of cloud cover obscuration, is an essential prerequisite for proper utilization of VHRR data for any meteorological and oceanograph ic applications. In this paper, we present a user-friendly algorithm t o overlay continental boundaries and geographical coordinate grids on VHRR images from geostationary satellites such as INSAT. The geometric scheme adopted for generating the required information is free from l imitations of cloud cover or lack of contrast in visible or thermal IR channel images. The algorithm produces satisfactory geolocation accur acies for most meteorological and oceanographic applications. The algo rithm is general and could be used for VHRR images from other geostati onary satellites (METEOSAT, GMS, and GOES) by incorporating the necess ary information about their VHRR scan characteristics. Copyright (C) 1 996 Elsevier Science Ltd