黑海西北部涡旋与环流对跨陆架水交换的影响

Effect of eddies and Rim Current on cross-shelf exchange in the northwestern Black Sea

涡旋对海洋中的能量传递和物质交换有重要作用。黑海西北部陆坡边缘是长生命周期涡旋经常发生的海域,但涡旋引起的陆架和海盆之间水交换通量的季节性特征,以及海盆边缘环流对跨陆架水交换的作用等方面的研究还不是很充分。本文对黑海西北部陆架区与深海盆区间的跨陆架水交换进行了研究,利用高分辨率三维原始方程模式模拟的温、盐、流等资料,结合涡旋自动探测方法,统计了黑海西北部海域的涡旋活动,研究了涡致跨陆架水交换的季节性特征,计算对比了2002年到2010年间海盆边缘环流与涡旋对跨陆架水交换通量的各自贡献。结果表明:黑海西北部地区海盆边缘环流强度与跨陆架进、出通量的相关系数分别为0.57和0.67,海盆边缘环流位置与跨陆架交换量的相关系数为0.52;海盆边缘环流强度与位置的季节性变化导致了黑海西北部跨陆架通量的季节性变化。黑海西北部地区表层3月到8月之间涡旋所引起跨陆架交换量约占了跨陆架交换总量的16%～31%;涡致跨陆架通量也具有季节性特征。文中对单个涡旋进行了详细研究:2005年5月5日到2005年7月20日之间在黑海西北部存在一个直径最大值时达到120km的反气旋式涡旋,涡旋存在期间完成了从陆架区向深海区的水体传输,相当于黑海西北陆架区水体积的30.9%。

Mesoscale eddies play an important role in energy transfer and material exchange in the ocean.Long-lived mesoscale eddies are frequently observed ocean processes at the shelf edge of the Black Sea.The researches about cross-shelf exchange are not enough,e.g.,the seasonal characteristics of the exchange flux between shelf and basin induced by eddies,and the role of Rim Current in the cross-shelf exchange are not clear.Based on a three-dimensional circulation model output,combined with automatic eddies detection method,this study calculated cross-shelf exchange between the continental shelf and the deep sea in the northwestern Black Sea from 2002 to 2010.The contributions of Rim Current and eddies to the exchange process were comparatively investigated.The correlation coefficients between the intensities of Rim Current in the northwestern Black Sea region and the inward and outward transport across the continental shelf are 0.57 and 0.67 respectively,and the correlation coefficient between the Rim Current location and the crossshelf exchange capacity is 0.52.Seasonal changes in intensity and location of the Rim Current lead to seasonal variations in the cross-shelf flux in the northwestern Black Sea.Eddies-induced cross-shelf exchange accounts for about 16%to 31% of the total cross-shelf exchange during March to August,in this research seasonality of cross-shelf flux has been confirmed.Even a single eddy is able to influence significantly the flux in the northwestern Black Sea.About volume of northwestern-shelf water was renewed by a single mesoscale eddy over the period 5 May to 20 July 2005,which is equivalent to 30.9% of the overall volume of shelf water.