Carried on MetOp, ASCAT (Advanced Scatterometer) uses radar to measure electromagnetic backscatter from the wind-roughened ocean surface, from which data on wind speed and direction can be derived.
ASCAT will achieve near global coverage in five days with a repeat cycle of 29 days (412 orbits). Since observations are made using radar, ASCAT provides day- and night-time imaging capabilities and is not affected by cloud cover.
By making observations of the same point on the ground from three directions, ASCAT reduces any ambiguity in the data and hence leads to more accurate information on wind speed and wind direction to feed into meteorological forecasting models. In addition, the dual swathes provide over twice the coverage of the earlier instruments on ERS-1 and ERS-2.
ASCAT's range discrimination diagram shows the use of a freqency modulation technique in conjunction with relatively long, medium power transmit pulses.
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