The primary application of the scatterometers is for Ocean Surface Wind Vectors. A scatterometer sends microwave pulses to the earth's surface and measures the backscattered power from the surface roughness elements. The back scatter power depends not only on the magnitude of the wind stress but also on the wind direction relative to the direction of the radar beam. The relation between backscatter signal and ocean surface winds is not well established under the strong wind and rainy conditions of a cyclone because of lack of validation. After the failure of NASA's NSCAT system, there has been rapid deployment of a new system called Quikscat that provides a wide swath of 1800 km and unprecedented global ocean coverage. Wind fields from quikscat are available on near real-time to most TC forecast offices. The standard wind product has a 25 km spatial resolution. The data has provided the outer wind structure of tropical cyclones. It is also used to determine the radius of 35 knots (De Muth et al., 2001), and for identifying closed circulations of developing systems and in providing lower limits for maximum sustained winds. Sarkar (2003) has reviewed techniques for surface wind measurements over global oceans from space platforms. The most successful wind sensor has been the microwave scatterometer.

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