Preliminary operational evaluation of WindSat ocean surface vector winds at the Tropical Prediction Center/National Hurricane Center
Michael J. Brennan, UCAR/TPC/NHC, Miami, FL; and R. D. Knabb
The Tropical Prediction Center/National Hurricane Center has tropical cyclone (TC) and marine analysis, forecast, and warning responsibility over a large area of the Eastern Pacific and Atlantic oceans. In these regions, observations of near-surface winds are limited to scattered buoys and transient ships; making remotely sensed ocean vector winds an integral part of the observational dataset in this area. Until now, the most heavily utilized ocean vector winds in TPC/NHC operations have been provided by the NASA QuikSCAT scatterometer, however, data from the multi-frequency polarized WindSat radiometer aboard the Air Force Coriolis satellite is now being received at TPC/NHC in near real time. WindSat is the first passive instrument to provide full ocean vector wind information, as previous radiometers have only provided wind speed information (e.g., SSM/I).
Evaluations of WindSat data will be presented in a variety of meteorological phenomena that occur in the TPC/NHC area of responsibility. WindSat estimates of maximum wind, outer wind radii, and center location will be evaluated for TCs. Additionally, the placement and characteristics of other features such as surface fronts, tropical waves, and surface high and low pressure centers will also be examined. Finally, the ability of WindSat to resolve gap wind events, such as those in the Gulf of Tehuantepec will also be evaluated. Comparisons will be made between the WindSat wind data and data from other observational platforms such as ship and buoy observations, the QuikSCAT scatterometer, aircraft reconnaissance, and the stepped-frequency microwave radiometer (SFMR).
The sensitivity of the WindSat wind solution to other co-located observed or derived parameters from the WindSat platform, including cloud liquid water, sea surface temperature, total precipitable water, and rain rate will be examined. Preliminary results have shown large sensitivity of the wind solution (both speed and direction) to the cloud liquid water field, particularly in regions of strong cloud water gradient. The relationship of the retrieved wind solution to cloud and rain water is of particular interest since winds from the QuikSCAT scatterometer exhibit a large sensitivity to rain.
The results from this evaluation will be used to train forecasters at TPC/NHC and elsewhere about how to best utilize the information provided by the WindSat platform. Also, data quality flags will be developed using results from this evaluation to identify areas where the retrieved wind solution is unreliable.
Extended Abstract (1.1M)
Session 6, New Observations
Wednesday, 17 January 2007, 4:00 PM-5:30 PM, 207A
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