Sunday, June 28, 2009

QuickScat finds tempests brewing in 'ordinary' storms

Science Daily: … In the decade since NASA's QuikScat satellite and its SeaWinds scatterometer launched in June 1999, the satellite has measured the wind speed and wind direction of these powerful storms, providing data that are increasingly used by the National Oceanic and Atmospheric Administration's (NOAA) National Hurricane Center and other world forecasting agencies. The data help scientists detect these storms, understand their wind fields, estimate their intensity and track their movement.

But tropical cyclones aren't the only storms that generate hurricane-force winds. Among others that do is a type of storm that dominates the weather in parts of the United States and other non-tropical regions every fall, winter and into spring: extratropical cyclones.

Scientists have long known that extratropical cyclones (also known as mid-latitude or baroclinic storms) sometimes produce hurricane-force winds. But before QuikScat, hurricane-force extratropical cyclones were thought to be relatively rare. Thanks to QuikScat, we now know that such storms occur much more frequently than previously believed, and the satellite has given forecasters an effective tool for routinely and consistently detecting and forecasting them.

…As confirmed in a 2008 study, QuikScat substantially extends the ability of forecasters to detect hurricane-force wind events in extratropical storms. For the studied case, QuikScat was able to identify more than three-and-a-half times as many hurricane-force events as combined data from the European ASCAT sensor on the METOP-A satellite, directly-measured buoy and ship information, and model predictions.

…QuikScat data have been instrumental in the ability to forecast hurricane-force extratropical cyclones several days in advance, while they are still well out over the ocean. Forecasters can use the data to determine which numerical weather prediction models are handling a storm the best, thereby improving the accuracy of forecasts and increasing warning lead times. QuikScat data are available to forecasters within three hours of acquisition….

Artist's conception of the QuikScat satellite, from one of the Gerhard Richters of NASA

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