Winds travelling over the surface of the oceans influence the radar backscattering properties of the surface of the sea in a way that is related to wind speed and direction. ASCAT will exploit this fact by transmitting pulses of microwave energy at 5.255 GHz (C-band) towards the surface of the Earth and then records the resulting echoes. These data will be used to derive wind speed and direction over the oceans for use in operational weather forecasting and climate research.
ASCAT's two sets of antennae provide two 550 kilometres wide swathes. Observations for each swathe are made sequentially so that each point on the ground is viewed three times, first by the fore-beam, then by the mid-beam and finally by the aft-beam.