北太平洋黑潮延伸体区域和副热带逆流区域中尺度涡能量特征研究

Mesoscale eddies energy characteristic in the Kuroshio Extension and north Pacific subtropical countercurrent region

不同科研工作者对黑潮延伸体区域和北太平洋副热带逆流区域的中尺度现象进行过不同的研究,但对两区域中尺度涡进行统一比较分析的工作较少。因此,本文利用11年的卫星高度计海表面高度异常资料分别对这两个区域的中尺度现象特征及其能量变化过程进行系统的分析和对比。研究发现,两区域的气旋涡与反气旋涡在分布、振幅、能量和寿命上均存在差异;进一步的动能谱分析和能量串级讨论发现:两区域的动能谱密度虽均集中在2×10–3~4×10–3周/km的波数域上,但黑潮延伸体区域大部分涡旋信号分布在经向上,而北太平洋副热带逆流区域主要分布在纬向上,这可能与两区域中尺度涡能量来源的不同有关。由于两区域在2×10–3~3×10–3周/km的波数域上动能转移项以负值为主,这说明两区域在此波数域上均存在能量源,并且发生能量逆向串级。

Different researchers have studied mesoscale phenomena of Kuroshio Extension(KE)and north Pacific subtropical countercurrent(STCC)area independently,but they have never made comparisons and analysis of the phenomenon in the two areas.In this paper,the mesoscale phenomenon and the change process of energy in these two regions are unified analyzed and compared by using the 11 years data of sea surface anomaly of altimeter.Firstly,the‘Okubo-Weiss algorithm’is used to detect and analyze the eddy,and concluded that there are differences in distribution,amplitude,energy and lifetime between the cyclonic eddies and the anticyclonic eddies in these two regions.Secondly,the kinetic energy spectrum and energy cascade of mesoscale eddies in the two regions are discussed by using the method of kinetic energy spectrum analysis.The kinetic energy spectral density of both regions is concentrated in 2×10–3 circle/km to 4×10–3 circle/km.The propagation direction of most of mesoscale eddies in the KE region are more meridionally,while that in the STCC region are more zonally.The kinetic energy transfer terms of the two regions are mainly negative in the range of 2×10–3 circle/km to 3×10–3 circle/km,which implied that there is an energy source in this wavenumber,meanwhile,there is an inverse cascade.