北太平洋海浪特征分析

利用最新的欧洲中尺度天气预报中心(ECMWF)提供的1979—2014年逐6 h的ERA-Interim有效波高和风速数据,分析近36a北太平洋海浪场的变化特征。结果表明:有效波高经验正交函数分解(EOF)的第1模态呈同相位分布,该模态与太平洋10 a涛动指数(PDO)和厄尔尼诺事件(ENSO)呈显著的遥相关,可以通过这些气候因子的变化来预测有效波高的年代际变化;第2模态表明北太平洋西部海域的有效波高有显著的递增趋势,而东部海域则逐渐减小;第3模态以45°N为界,西风带呈现高低纬反相的双涡型分布,并有显著的2.5 a左右年际变化周期。北太平洋海域有效波高和风速重现期极值的大值区位于西风带,重现期越长,日本群岛南部海域风速加强越显著,加强的极值区延伸到中国的东海甚至是菲律宾群岛的东部海岸。

Analysis of wave characteristics in North Pacific Ocean

Using the latest ERA-Interim sea surface wind field and wave field data from every 6 h from 1979 to 2014 provided by the European Centre for Medium-Range Weather Forecasts(ECMWF), the wave characteristics in the North Pacific Ocean for the last 36 years were analyzed. The results show that the first mode decomposed from the empirical orthogonal function(EOF)of significant wave height(H_s)exhibits in-phase change rules and is teleconnected with the Pacific Decadal Oscillation(PDO)and El Niñ o-Southern Oscillation(ENSO); the second mode shows that H_s exhibits a significant increasing trend in the western region of the North Pacific Ocean, and a gradually decreasing trend in the eastern region of the North Pacific Ocean; and the third mode mainly exhibits inverse double-eddy-type distributions at high and low latitudes in the westerlies, with 45°N as a boundary. The maximum extremes of H_s and wind speed for different return periods appear in the westerlies; for a relatively long return period, wind speed shows a significant increase in the area to the south of Japanese islands. The area with increased extremes extends to the East China Sea or even the east coast of Philippine islands.