基于矢量经验正交分析方法的琼州海峡定点锚系站余流分析

Vector EOF analysis of residual current of an anchor station in the Qiongzhou Strait

利用布放在琼州海峡西口的一个座底式锚系站获取的2007年2、4月各30 d的高精度海流连续观测数据,在常规分析基础上,进一步采用矢量经验正交分析(Vector EOF)方法对其余流场进行时空分解,结果表明:(1)4月各层余流的最大值均大于2月.在月平均意义上,2、4月各层余流分别介于5.3～6.7和2.3～4.1 cm/s之间,两月均以西向流为主.(2)风是造成琼州海峡西口西向余流占主导地位的重要原因之一.(3)Vector EOF分解后,两月的第一模态贡献率均高于90%,表明两月的余流均以东西向的流动为主.两月的第二模态均表明余流在垂向结构上有上、下水层流向相反的特点,2月表现为南北反向,4月表现为东西反向.(4)琼州海峡西口余流的流态主要有5 d左右的时间变化.

Based on the routine analysis of the 30 days high-precision and continuous current observation data of an anchor station in the west gate of the Qiongzhou Strait in February and April of 2007, this article further employed the Vector EOF method to conduct a spatio-temporal decomposition on the residual current field. The results show that ： （ 1 ） The maximum April value of residual current velocity in every aqueous layer is greater than the maximum February value. In respect of the monthly mean residual current, the February value is 5.3 - 6.7 cm/s and the A- pril value is 2.3 - 4.1 cm/s in all aqueous layers, and both with west as the main direction. （2） Wind is one of the important factors that established the dominance of the westward residual current. （3） The results of Vector EOF decomposition show that ： contribution rates of the first modes in February and April are all higher than 90% , indicating the dominance of east-west flow in the residual eun＇ent in two months. The second modes of the two months indicate that the residual current have vertical structure feature that water flows in opposite direction in upper and lower aqueous layers, displayed as south-north in February and east-west in April. （4） The main time change of residual current is about 5 days.