Statistical features of strong wind over the Bohai and Yellow Sea and its multimodel ensemble prediction during boreal summer

Abstract

Based on the surface wind and geopotential height fields of the NCEP/NCAR reanalysis data during the period from January 1, 1980 to December 31, 2009 and forecast data of the JMA, NCEP GFS and NOGAPS models, statistical features of the strong wind have been investigated, and the bias-removed ensemble mean (BREM) forecast experiment of the sea surface wind has been conducted over the Bohai and Yellow Sea for the period from July 28 to August 10 in 2009. The results show that the strong wind days over the Bohai and Yellow Sea have a significant interannual variability and seasonal variability. On average, there are 50 strong wind events which last for at least 12 hours annually. In addition, strong windy weather events occur most frequently in winter and less frequently in summer. The strong wind events in summer are mainly attributed to the northward movement of the typhoons in the western Pacific, while those in winter are mainly brought by the cold fronts. The first two EOF eigenvectors describe the activities of tropical cyclones over the East China Sea and the Yellow Sea, respectively, together with the high pressure system in the northeastern China. Large pressure gradient between the high and low pressure systems results in the strong windy weather over the Bohai and Yellow Sea. On the whole, the BREM forecast technique performs better than each of three single model forecast in terms of the forecast skill of the surface wind over the Bohai and Yellow Sea for the forecast period from July 28 to August 10 in 2009.