Application of Satellite-Derived Ocean Surface Winds to the Detection of Weather Systems and the Prediction of Near-Ocean Surface Winds around Hawaii


The Hawaiian Island chain is surrounded by the open ocean and is an ideal place to conduct the application of QuikSCAT satellite-derived ocean surface winds to the detection of weather systems. With the help of QuikSCAT winds, the associated circulation of the weather systems over the open ocean around Hawaii can be identified. In this study, the obvious cyclonic circulation associated with a Kona storm, the significant wind shift and wind confluence related to the surface cold front, and the anticyclonic circulation related to high-pressure systems for both a strong-wind event and a trade-wind condition are revealed over the open ocean through QuikSCAT winds. The propagation of a cold frontal boundary, defined by the wind shift and wind confluence, also can be clearly detected using the reanalyzed ocean-surface winds.

With the assimilation of QuikSCAT winds into the WRF 3D-Var system, the under-estimation of near-ocean surface winds in the Hawaiian Islands and the surrounding ocean by the Global Forecasting System (GFS) and NCEP reanalysis can be improved in the analyzed low-level winds and the associated short-term forecast, including the effects of the Island obstacle on near-ocean surface winds. To statistically evaluate the prediction of near-ocean surface winds under the influence of the most frequent weather systems and events in Hawaii, the numerical weather predictions with/without assimilated QuikSCAT wind data are performed. The results reveal that the predicted 10-m wind speed/direction during the 24-hr forecast results in a relatively smaller mean squared error (MSE) with assimilated QuikSCAT winds as compared with the GFS/NCEP-FNL run for the ocean surrounding Hawaii.

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