Inclination Trend of the Agulhas Return Current Path in Three Decades
Inclination Trend of the Agulhas Return Current Path in Three Decades
复制标题
DOI：
10.3390/rs15245652
复制
发表时间：
2023-12
期刊：
影响因子：
--
通讯作者：
Yan Lin;Liru Lin;Dongxiao Wang;Xiao-Yi Yang
中科院分区：
文献类型：
--
作者：
Yan Lin;Liru Lin;Dongxiao Wang;Xiao-Yi Yang
厄古拉斯回流（ARC），作为厄古拉斯系统的主要组成部分，有助于印度洋和大西洋盆地南部之间的水交换和物质输送。在这项研究中，卫星高度计数据和再分析数据集，以及一套新的标准，分段定义的喷流轴，探讨了长期变化的ARC的轴的位置在最近三十年。结果表明，ARC轴呈明显的倾斜趋势，其西部（35-48°E）向北偏移，东部（48-70°E）向南偏移。ARC路径的纬向移动可归因于大尺度风强迫。由于Ekman泵吸机制导致的异常海面风应力旋度，导致了西部海区正-负-正的海面高度异常和东部海区负-正-负的海面高度异常，从而导致了ARC轴向西北-东南方向的倾斜。进一步的分析表明，这种弧倾斜趋势更多地依赖于下游轴的南移，而不是地形转向上游。下游轴更可能与ACC锋相互作用，其迁移可能通过改变背景环流和能量级联方向来控制当地的EKE模式。在35°E以西的河源区，ARC轴更易受地形影响，EKE的变化更易受涡旋活动过程的控制，包括涡旋的脱落、传播和合并。本研究为ARC的长期变化及其与局部EKE变化的相互作用提供了新的认识。
The Agulhas Return Current (ARC), as a primary component of the Agulhas system, contributes to water exchange and mass transport between the southern portions of the Indian and Atlantic Ocean basins. In this study, satellite altimeter data and reanalysis datasets, and a new set of criteria for the piecewise definition of the jet axis are used to explore the long-term change of the ARC’s axis position in recent three decades. It is found that the ARC axis exhibits a significant slanting trend with its western part (35–48°E) migrating northward and the eastern part (48–70°E) migrating southward. The meridional movement of the ARC path could be attributed to large-scale wind forcing. The anomalous surface wind stress curl, by Ekman pumping mechanism, leads to positive–negative–positive sea surface height anomalies in the western section and negative–positive–negative anomalies in the eastern section, thus the ARC axis tilts accordingly, in a northwest–southeast direction. Further analysis suggests that this ARC slanting trend is more dependent on the southward shift of the downstream axis and less on the topographic steering upstream. The downstream axis is more likely to interact with the ACC fronts and its migration could dominate the local EKE pattern by changing the background circulation and energy cascade direction. For the headstream west of 35°E, the ARC axis is more subject to topography, thus the EKE change is more dominated by eddy activity processes, including shedding, propagation and merging. This study provides some new insights into the long-term change of ARC and its interaction with the local EKE variability.