ABSTRACT It has been widely known that the coastal upwelling along the southern coast of Java is generated by southeasterly wind which induces offshore Ekman Mass Transport (EMT) during southeast monsoon. However, the variability of EMT has not been fully described in previous studies. The present study investigated the variability of Ekman dynamics which consist of EMT and Ekman Pumping Velocity (EPV) along the southern coast of Java, based on remotely sensed data. We demonstrated the incongruity between the distribution of southeasterly wind speed and sea surface temperature (SST) during southeast monsoon which is related to the distribution of Ekman dynamics. Offshore EMT at the western region of the southern coast of Java is stronger than offshore EMT at the eastern region. However, stronger offshore EMT at the western part is inhibited by downwelling EPV while weaker offshore EMT at the eastern part is accelerated by upwelling EPV. Consequently, SSTs at the eastern parts are lower than those at the western parts. Thus, the changes of offshore EMT intensity from eastern to western parts are balanced by their EPV distributions which explain the incongruity between the distribution of wind speed and SST during southeast monsoon. On an interannual timescale, the combination of La Niña and negative Indian Ocean Dipole (IOD) events tends to weaken offshore EMT and EPV which reduce the intensity of Chl-a bloom and SST cooling during southeast monsoon season. Furthermore, ENSO has a less significant impact on the Ekman dynamics variability than IOD.

中文翻译：

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卫星数据揭示了爪哇南部海岸的埃克曼动态变化

摘要 众所周知，爪哇南部海岸的沿海上升流是由东南季风期间引起离岸埃克曼质量输送 (EMT) 的东南风产生的。然而，先前的研究并未完全描述 EMT 的可变性。本研究基于遥感数据调查了沿爪哇南部海岸由 EMT 和 Ekman 泵送速度 (EPV) 组成的 Ekman 动力学的可变性。我们证明了东南季风期间东南风速和海面温度（SST）分布之间的不协调性，这与 Ekman 动力学的分布有关。爪哇南部沿海西部地区的海上 EMT 强于东部地区的海上 EMT。然而，下流EPV抑制了西部较强的海上EMT，而上流EPV加速了东部较弱的海上EMT。因此，东部的海温低于西部的海温。因此，海上 EMT 强度从东到西的变化与其 EPV 分布相平衡，这解释了东南季风期间风速和 SST 分布的不一致。在年际时间尺度上，拉尼娜现象和负印度洋偶极子 (IOD) 事件的结合往往会削弱离岸 EMT 和 EPV，从而降低东南季风季节 Chl-a 绽放和 SST 冷却的强度。此外，ENSO 对 Ekman 动力学变异的影响不如 IOD。