Power density of ocean surface wind from international scatterometer tandem missions

For 6 months between April and October 2003, two identical scatterometers flew in tandem. Their observations demonstrate the need for more than one scatterometer in the polar orbit to include sufficient temporal variability and reduce aliasing of ocean surface wind-stress measurements required for applications such as estimating electricity generation potential and ocean-atmosphere gas exchange. The energy deficiency over a 12-h period, evident in the data from one scatterometer, is eliminated with the additional scatterometer. The missions in tandem allow an improved understanding of the diurnal variability from coastal regions to the open ocean. The power density distributions were found to be very different at the different sampling times of the two satellites. Two scatterometers will be launched by India and China in the next few years and will fly in tandem with the scatterometers of the USA and Europe, which are already in operation. The potential improvement in the coverage of ocean wind stress by this constellation is analysed and discussed. The constellation is found to meet the 6-hourly revisit requirement of operational weather forecasting over most of the ocean.