Applications of the ERS wind scatterometer

Wind scatterometers use accurate measurements of the radar backscatter from the ocean surface when illuminated by a microwave signal with a narrow spectral bandwidth to derive information on ocean surface wind velocity. At a given angle to the flight path of the satellite, the amount of backscatter depends on two factors - the size of the surface ripples of the ocean, and their orientation with respect to the propogation direction of the pulse of radiation transmitted by the scatterometer. The first is dependent on wind stress and hence wind speed at the surface, while the second is related to wind direction. Hence measurements by the ERS scatterometer may be used to derive both wind speed and direction.

Scatterometer instruments aim to achieve high accuracy measurements of wind vectors, and resolution is of secondary importance - the resolution of the ERS scatterometer is 50km, though the grid sampling is 25km. Because the scatterometer operates at microwave wavelengths, the measurements are available irrespective of weather conditions.

Information from the ERS wind scatterometer provides a unique source of data on sea surface wind speed and direction which has important applications in weather and wave forecasting and the investigation of climate models and elaboration . The assimilation of scatterometer data into atmospheric forecasting models greatly improves the description of cyclonic features so important in predicting future weather patterns.

There are numerous other applications, such as the measurement of sea ice extent and concentration, and emerging land applications such as regional-scale monitoring of ice shelves, rainforests and deserts.