海洋锋海表风速最小值及其成因
发布时间：2018-08-29 10:53
【摘要】：利用2000—2008年AVHRR、QuickSCAT等高分辨率卫星观测资料和CFSR再分析资料,分析了墨西哥湾流区、东海黑潮锋区、巴西-马尔维纳斯合流区和厄加勒斯回流区等全球主要海洋锋区的大气响应特征,发现在上述海洋锋区普遍存在海表矢量风速的最小值分布,并对这一现象的产生原因进行探讨。研究指出:夏季(6—8月)墨西哥湾流区、6月东海黑潮锋区附近有明显的矢量风速最小值分布,而巴西-马尔维纳斯合流区及厄加勒斯回流区海洋锋附近则终年存在矢量风速最小值。产生这一现象的条件是大尺度气压背景场梯度方向与海洋锋附近海表温度梯度方向接近一致,其物理过程为:海洋锋暖(冷)水区一侧上空对应有低(高)气压,由此产生的局地气压梯度与大尺度背景气压梯度方向接近相反,导致锋区附近叠加后的气压梯度最小,海表风速因此也最小。同时,摩擦作用使海表风偏向低压一侧,于是沿锋区走向(跨锋区走向)的风速分量差在暖水区一侧产生气旋性切变涡度(风速辐合),进而造成上升运动和强降水,而该分量差在冷水区一侧则产生相反的大气响应特征。
[Abstract]:Based on the high resolution satellite observations such as AVHRR,QuickSCAT and CFSR reanalysis data from 2000 to 2008, the Gulf Stream and the Kuroshio front in the East China Sea are analyzed. The atmospheric response characteristics of the major global ocean fronts, such as the Brazilian-Malvinas confluence zone and the return zone of Ogharest, show that the minimum distribution of sea surface vector wind speed exists generally in these sea fronts. The causes of this phenomenon are also discussed. It is pointed out that in the summer (June-August) Gulf Stream, there is an obvious minimum distribution of vector wind speed near the Kuroshio front in the East China Sea in June. However, the minimum vector wind speed exists all year round near the oceanic front in the Brazilian-Malvinas confluence area and in the reflux area of Ogharest. The condition for this phenomenon is that the gradient direction of large-scale atmospheric pressure background field is close to the direction of sea surface temperature gradient near the ocean front, and the physical process is that there is a low (high) pressure over the warm (cold) water area of the ocean front. The resulting local pressure gradient is close to the reverse direction of the large-scale background pressure gradient, resulting in the minimum pressure gradient near the frontal area and the minimum sea surface wind speed. At the same time, the friction makes the sea surface wind incline to the low pressure side, so the difference of the wind velocity component along the front area (across the front zone) produces the cyclonic shear vorticity (convergence of the wind speed) on the warm water area, and then causes the rising motion and the heavy precipitation. On the other side of the cold water zone, this component difference produces the opposite atmospheric response.
【作者单位】： 南京信息工程大学气象灾害预报预警与评估协同创新中心和气象灾害教育部重点实验室;
【基金】：江苏高校优势学科建设工程资助项目(PAPD)资助
【分类号】：P732
本文编号：2210983
[Abstract]:Based on the high resolution satellite observations such as AVHRR,QuickSCAT and CFSR reanalysis data from 2000 to 2008, the Gulf Stream and the Kuroshio front in the East China Sea are analyzed. The atmospheric response characteristics of the major global ocean fronts, such as the Brazilian-Malvinas confluence zone and the return zone of Ogharest, show that the minimum distribution of sea surface vector wind speed exists generally in these sea fronts. The causes of this phenomenon are also discussed. It is pointed out that in the summer (June-August) Gulf Stream, there is an obvious minimum distribution of vector wind speed near the Kuroshio front in the East China Sea in June. However, the minimum vector wind speed exists all year round near the oceanic front in the Brazilian-Malvinas confluence area and in the reflux area of Ogharest. The condition for this phenomenon is that the gradient direction of large-scale atmospheric pressure background field is close to the direction of sea surface temperature gradient near the ocean front, and the physical process is that there is a low (high) pressure over the warm (cold) water area of the ocean front. The resulting local pressure gradient is close to the reverse direction of the large-scale background pressure gradient, resulting in the minimum pressure gradient near the frontal area and the minimum sea surface wind speed. At the same time, the friction makes the sea surface wind incline to the low pressure side, so the difference of the wind velocity component along the front area (across the front zone) produces the cyclonic shear vorticity (convergence of the wind speed) on the warm water area, and then causes the rising motion and the heavy precipitation. On the other side of the cold water zone, this component difference produces the opposite atmospheric response.
【作者单位】： 南京信息工程大学气象灾害预报预警与评估协同创新中心和气象灾害教育部重点实验室;
【基金】：江苏高校优势学科建设工程资助项目(PAPD)资助
【分类号】：P732
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