Thursday, 18 October 2001
Near-realtime Winds and Surface Pressures from SeaWinds
High quality surface winds are available over the world’s oceans from SeaWinds, the latest scatterometer launched by NASA aboard the QuikSCAT satellite. It’s wide swath (1,800 km) and high resolution (25 km within the swath) provides valuable observations of wind speed and direction over the data-sparse oceans near their forecast areas. The Center for Ocean-Atmospheric Prediction Studies (COAPS), in cooperation with NOAA/NESDIS, is providing graphical representations of the surface winds and adjusted surface pressures on a near-realtime basis to the National Weather Service (NWS) Forecast Offices at Upton, New York and Tallahassee, Florida. Winds are plotted from directly from the SeaWinds observations, while surface pressures are computed using a variational technique. Surface pressures are compared to the latest ETA model output. These graphics are available to forecasters twice daily as the satellite passes over their area and contain information on the direction and intensity of the marine wind field, locations of fronts and low pressure centers, pressure gradients, and the development of tropical cyclones. A pilot project (funded through COMET) has shown that this information is useful to forecasters. Work is underway to supply NWS with winds and surface pressures as digital files, which can be incorporated into the AWIPS suite of products and be more accessible to the forecasters.
We are also working in cooperation with the NWS to improve identification of rain contamination in the retrieved winds. Currently, there are excessive false alarms, which results in the loss of data near meteorologically interesting features. Several approaches for scatterometer-based estimates of rain rate are being examined. A plan for using these rain-rates and pressures to enhance the quality of the rain-contamination flag will be discussed.
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