棉兰老流与棉兰老潜流季节内变化研究

Intraseasonal Variability of the Mindanao Current and the Mindanao Undercurrent

通过分析HYCOM(HYbrid Coordinate Ocean Model)数据,得出棉兰老流(MC)位于0~800m深度,紧贴岸界,最大流速发生在次表层。棉兰老潜流(MUC)位于400m深度以下,127°E以东离岸侧,最大流速发生在1 600m深度处。MUC的流核数目在12个月的分布不尽相同,大概在1~3个,其中存在2个流核的月份最多;MUC各个流核在不同月份的核心强度有明显变化,5月份流核核心速度最大,可达10cm·s^(-1);MUC各个流核的纬向剖面面积也有明显的季节变化,2月份的剖面面积最大。从季节内变化上看,MUC与MC都存在较明显的季节内变化信号,周期在100d左右。MC的季节内变化是由海表面涡旋引起的,而MUC的季节内变化是由温跃层以下的涡旋引起的。

The MC and the MUC play an important role in contributing to equatorial heat and mass budget and act as important channels of mass,heat,and salt exchange between two hemisphere.In this paper,the structure and the intraseasonal variability of the MC and the MUC have been analyzed using the HYCOM data.The MC is a northward currentin the depth of 0～800m with its maximum velocity in the subsurface.And the MUC lies below the 400 mdepth,east of 127°E offshore,with maximum velocity in 1 600 mdepth.The climatological monthly mean velocities showed significant seasonal variabilities in both quantity and the strength of the MUC velocity cores.The cores of MUC varied with months from one to three with tow cores in most time.The strength and area of MUC also varied significantly.The core velocity attained the largest of up to 10cm·s-1 in May,with the largest areas occurring in February.Both the MC and the MUC have strong intraseasonal variability of about 100 d.The intraseasonal variability of MC maybe caused by the activity of surface eddies and the intraseasonal variability of MUC appears to be closely related to subthermocline eddies,which translate westward.