2004年至2008年间棉兰老穹窿海域温跃层深度变化对涡旋动能的影响

The Impact of Thermocline Depth on EKE Variation in Mindanao Dome Region

利用卫星观测的海表面高度异常数据和HYCOM(Hybrid Coordinate Ocean Model)模式的全球同化数据,考察了2004年至2008年间棉兰老穹窿(Mindanao Dome,MD)海域涡旋动能(Eddy Kinetic Energy,EKE)的变化特征,并探讨了影响EKE时间变化的物理机制,发现MD海域EKE变化和温跃层深度变化密切相关。从2004-2008年间,MD海域温跃层深度逐渐加深,导致背景流场的经向梯度减弱,引起MD南部海域EKE的逐渐降低。进一步研究发现EKE的变化是背景密度场和流场经向梯度共同影响的结果,其中流场梯度的影响更大,密度梯度的影响则主要在次表层。而2004年至2008年间ENSO信号和局地风应力旋度因未引起背景场经向梯度的响应,故对EKE的影响并不明显。

Using satellite altimetry observations and the global assimilation data from the Hybrid Coor- dinate Ocean Model（HYCOM）, the variation characteristic of Eddy Kinetic Energy （EKE） and the mechanisms that influence the temporal variation of EKE in the Mindanao Dome（MD）region during 2004-2008 are investigated. The results show that the variation of EKE and the thermocline depth are closely related. The thermocline deepened in the MD region during 2004-2008, causing the decrease of meridional gradient of background flow, which in turn resulted in weakened EKE in the southern region of the MD. It is shown that both the meridional gradient of background zonal flow and the density dom- inate the variation of EKE in the southern region of the MD, while the meridional gradient of zonal flow has greater influence on EKE and the effect of meridional gradient of density mainly exists in the sub- surface. The ENSO and the local wind stress curl have little influence on EKE in the MD region, for they do not change the meridional gradient of background flow obviously.