Seasonal and interannual variability of sea surface wind over the China seas and its adjacent ocean from QuikSCAT and ASCAT data during 2000-2011

A total of 12 years (2000-2011) of sea surface wind data from QuikSCAT and ASCAT are employed to examine the seasonal and interannual variability over the China Seas and its adjacent ocean. The wind speed and direction, strong wind frequency, monsoon onset and transition time are revealed by statistic analysis. The result shows that (1) the wind speed is highest in winter and lowest in summer in the study area. The Southeastern Vietnam, Luzon Strait, Taiwan Strait and the eastern ocean of Japan are the regions with the higher wind speed throughout the year, especially more than 12 m/s in winter. (2) The monsoon prevails in the China Seas, southwesterly in summer and northeasterly in winter, while southeast wind also occurs all the seasons except winter. The northwest wind only occurs in the north of 27 degrees N in winter. (3) The strong wind more than 10.8 m/s exceeds 140 days per year in the Taiwan Strait while only 30 days in the Bohai Sea and Yellow Sea. In addition, the Luzon Strait can reach 120 days with strong wind larger than 10.8 m/s, ranking the second after the Taiwan Strait. (4) The time of monsoon onset changes from year to year. Generally, the southwest wind in the low latitudes begins in May and ends in September or October, then turns to northwest wind completely which almost have no transition time. For the mid-latitudes zone, the southwest wind begins in June and ends in August. May and September are the transition time. Then the northeast wind begins to prevail. (5) The trend of sea surface wind speed in the study area is increasing from 2000 to 2011, except the Southeastern Vietnam. The annual mean wind speed is lowest in 2002 and 2010 during the period of 2000-2011.