VARIOUS TRENDS IN BACKSCATTER OF NATURAL TARGETS ON LAND OBSERVED IN QUICKSCAT DATA AT KU-BAND

Now a days there are few areas on the surface of earth having a relatively constant BSC and can serving as radar calibration targets. Few Examples include the Amazon rain forest, the Greenland ice sheet etc. In this paper we analyse a consistent set of Ku-band radar measurements from the QuickSCAT data mission for about ten years. To study the long-term variation of observed BSC, a set of data is required from Earth's surface this band. A global survey of potential constant land targets is performed. To identify the locations of the best natural calibration targets Quantitative measurements of temporal and spatial variabilities (homogeneity) and isotropy are used. By concentrating on low variation areas, useful calibration targets for future radar missions and for inter calibration between existing radars can be identified. By focusing on regions with little spatial heterogeneity, the temporal variations on diurnal, seasonal, and also decadal scales in homogenous natural terrain types including rain forest, dry brushy areas, and ice sheets can be analysed. The Greenland ice sheet shows a significant trend in backscatter in recent years, and therefore, may not be a suitable calibration site anymore. Another location for a good stable target is a dry brushy area in the Sahara, which shows comparable stability and isotropy with those of the Amazon, Congo, and Antarctica.