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渤、黄海风生流场季节循环时空模态与变异
石强
0
(海洋溢油鉴别与损害评估技术国家海洋局重点实验室,山东 青岛 266033;国家海洋局北海环境监测中心,山东 青岛 266033;山东省海洋生态环境与防灾减灾重点实验室,山东 青岛 266033)
摘要:
根据1978—2015年渤、黄海沿岸观测风应力场与二维非线性垂直平均风生流模式,以及旋转经验正交函数(REOF)、调和分析等方法,研究了渤、黄海月平均风生流速度势、流函数场季节循环时空模态与年际变异.渤、黄海月平均风生流速度势、流函数场主要有两种时空模态,季节周期分量是时空模态的主要分量.由于风应力场季节循环变异,渤海流函数场季节时空循环变异程度大于速度势场,速度势、流函数场第二模态是季节变异的主要分量,黄海速度势场季节时空循环变异程度大于流函数场,速度势场第二模态是季节变异的主要分量.由于月平均风应力场强度年际变化显著线性减弱,渤、黄海季节平均风生流场强度年际变化也显著减弱.渤、黄海暖流与冷水团季节生消是风生流水平环流与垂直对流对冷暖水体输送与汇集共同作用的结果,渤、黄海春、夏季辐合上升环流延缓及减弱了浅层暖水向深层传播,是春、夏季冷水团与温跃层形成的重要动力因素,因此,速度势是研究渤、黄海风生流场十分重要的因素.冬季渤海中部、黄海东部反气旋型及辐散下沉环流与黄海中部气旋型环流、辐合上升环流是黄海暖流季节转换与强度的主要动力控制因素,夏季黄海东部气旋型环流、辐合上升环流与黄海中部反气旋型环流、辐散下沉环流是黄海冷水团季节转换与强度的主要动力控制因素.
关键词:  海洋物理学  风生流场  速度势  流函数  时空模态  REOF分析  渤海  黄海
DOI:10.3969/J.ISSN.2095-4972.2018.04.004
基金项目:海洋溢油鉴别与损害评估技术国家海洋局重点实验室资助项目(2015010)
Spatio-temporal modes and variation on the seasonal cycle of wind-driven current field in the Bohai Sea and the Yellow Sea
SHI Qiang
(Key Laboratory of Marine Spill Oil Identification and Damage Assessment Technology, SOA, Qingdao 266033, China;North China Sea Environmental Monitoring Center, SOA, Qingdao 266033, China; Shandong Province Key Laboratory of Marine Ecological Environment and Disaster Prevention and Mitigation, Qingdao 266033, China)
Abstract:
Based on the wind stress field observed along the coast of the Bohai Sea and the Yellow Sea from 1978 to 2015, the spatio-temporal modes and interannual variation on the seasonal cycle of monthly mean wind-driven current field in the Bohai Sea and the Yellow Sea were studied with methods of two dimensional nonlinear vertical average wind-driven current model, Rotated Empirical Orthogonal Function (REOF) and harmonic analysis. The results show that the seasonal cycle of monthly mean wind-driven current velocity potential and stream function field are divided into two spatio-temporal modes. The seasonal periodic component is the main component of the spatio-temporal modes. Due to seasonal variation of monthly mean wind stress field, the seasonal spatial and temporal variation of the stream function field in the Bohai Sea is greater than that of the velocity potential field, and the second mode of velocity potential and stream function field are the main component of seasonal variation. The seasonal spatial and temporal variation of the velocity potential field in the Yellow Sea is greater than that of the stream function field, and the second mode of the velocity potential field is the main component of the seasonal variation. Due to the interannual variation of monthly mean, the wind stress field strength in the Bohai Sea and the Yellow Sea decreases significantly and linearly while the interannual variation of seasonal mean wind-driven strength decreases significantly. The seasonal growth and disappearance of warm current and cold water mass in the Bohai Sea and the Yellow Sea is the interaction results of wind-driven current due to horizontal circulation and vertical convection of cold-warm water mass transportation and convergence. The convergence upwelling circulation during spring and summer in the Bohai Sea and the Yellow Sea delay the transmission of shallow warm water to the deep layer, and was an important driving force for the formation of cold water mass and thermocline in spring and summer. Therefore, the velocity potential is a very important factor in the study of the Bohai Sea and the Yellow Sea wind-driven current field. The anticyclonic and divergence downward circulations in central Bohai Sea and the eastern Yellow Sea, the cyclonic and convergence upwelling circulation in central Yellow Sea in winter are the main dynamic control factors for the seasonal transition and intensity of the Yellow Sea Warm Current. The cyclonic and convergence upwelling circulation in eastern Yellow Sea, the anticyclonic and divergence downward circulation in central Yellow Sea in summer are the main dynamic control factors for the seasonal transition and intensity of the Yellow Sea Cold Water Mass.
Key words:  Ocean physics  wind-driven current field  velocity potential  stream function  spatial temporal modes  REOF analysis  Bohai Sea  Yellow Sea

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