近海面风场对黄东海域海平面特征影响的分析与模拟

Analysis and simulation of the wind fields impact on sea level features of Yellow Sea and East China Sea

基于1993—2012年TOPEX/Poseidon(T/P)卫星海平面异常SLA(Sea Level Anomaly)数据和FSCR(Climate Forecast System Reanalysis)再分析风场资料,分析黄东海域近20 a海平面的时空分布特征,尤其是不同时间尺度风场影响的变化特征,进而通过区域海洋模式对海面高度短期变化的可能机制进行探讨。结果表明:1)黄东海域海平面多年平均状态为南高北低,近海面季节性风场在岸线分布和海水热膨胀特征下,造成海面冬春季偏低,夏秋季偏高。近20 a黄东海域平均风速逐步减弱,平均海面上升速率为2.9 mm/a。2)风场的短期活动主要为灾害性大风,统计显示冬夏寒潮大风和台风大风均呈频数减少、强度增强的趋势。运用FVCOM(Finite Volume Community Ocean Model)模拟分析台风和寒潮作用下黄东海域海平面的变化,发现台风强风可形成辐散式海流气旋式涡旋,对应海面为下凹负值中心;北路寒潮大风可形成海流反气旋式涡旋,对应海面为上凸正值中心。两类涡旋的强海流部分增强了海面倾斜度。3)强海流部分动能和动量迅速向海水深部下传,无论在深度和强度上,寒潮造成的海流涡旋动能和动量下传比台风涡旋更迅速,更强。这与寒潮降温引起的海洋层结不稳定对流作用有关。

Based on the TOPEX / Poseidon（ T / P） satellite sea level anomaly（ SLA） data during 1993—2012 and FSCR（ Climate Forecast System Reanalysis） w ind data,the temporal—spatial features of sea level of Yellow Sea and East China Sea w ithin the 20 years are analyzed. The impacts of w ind fields w ithin different periods on the sea level are investigated,and the possible mechanisms of sea level change of short duration are studied by FVCOM（ Finite Volume Community Ocean M odel）. The results show that the average sea level of Yellow Sea and East China Sea in recent 20 years is high in southern and low in northern; seasonal w ind fields near the sea surface w ith coastal distribution and sea w ater thermal sw elling together force the sea level plus deviations in summer and autumn,and minus deviations in w inter and spring. The average w ind speed near the sea surface is gradually decreasing and the sea level rising speed is about 2. 9 mm / a during the 20 years. The short duration actions of w ind field mainly present as disastrous w ind events. According to statistics,both the summer typhoon and the w inter cold w ave show a trend of decrease in frequency and increase in intensity during the 20 years. The FVCOM model is used to simulate and analyze the sea level changes of Yellow Sea-East China Sea under typhoon and cold w ave impacts,and results show that the strong typhoon w ind creates the divergent cyclone vortex of sea current w ith sea level of negative low surface center,w hile the strong cold w ave w ind from north creates the anti-cyclone vortex of sea current w ith sea level of positive high surface center. The strong sea current areas in the tw o types of vortexes increase the sea surface gradient. Due to the unstable sea temperature profile w ith depth and the active convection impact caused by the w inter cold w ave,the kinetic energy and momentum w ere transported dow nw ards more faster in depth and intensity,compared w ith that of summer typhoon.