Advective pathways and transit times of the Red Sea Overflow Water in the Arabian Sea from Lagrangian simulations
Advective pathways and transit times of the Red Sea Overflow Water in the Arabian Sea from Lagrangian simulations
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DOI：
10.1016/j.pocean.2021.102697
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发表时间：
2021-10
影响因子：
4.1
通讯作者：
V. Menezes
中科院分区：
文献类型：
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作者：
V. Menezes
本研究调查了红海流出区释放的虚拟粒子的平流路径和过境时间，以此作为鲜为人知的红海溢流水(RSOW)在阿拉伯海扩散的替代。这项工作使用Parcels工具箱，一个拉格朗日框架，模拟了不同初始条件下的数万条轨迹。在RSOW层内的等压面和等轴面上进行了六种不同的拉格朗日模拟。所有的模拟都是基于富涡的GLORYS12再分析，它将过去20年收集的几乎所有现场(温度-盐度)观测和卫星观测合并到一个动力学框架中。这项研究表明，GLORYS12较好地再现了RSOW到亚丁湾的气候季节循环和曼达布海峡交换的基本特征。亚丁湾合成轨迹和RAFOS漂浮物的统计比较证实了用于拉格朗日模拟的GLORYS12速度场的质量。发现了六条主要的平流路径(按偏好顺序)：西南、西北、索科特拉通道、中部、东部和南部。Argo漂浮物的轨迹为其中一些路径提供了观测支持。尽管大多数粒子是从索马里附近的阿拉伯海输出的，但模拟显示了RSOW与阿拉伯海内陆及其东部边界的强大连接。颗粒在内部有很长的轨迹，这一事实增加了RSOW与更新鲜和缺氧的环境水混合的可能性。因此，这些路径可能对阿拉伯海及其他地区的盐分和氧气收支产生深远影响，因为RSOW也是全球倾覆环流的一部分，并通过阿古拉海流输出到印度洋。过境时间分布表明，外流来源的颗粒扩散到整个亚丁湾需要大约六个月的时间，沿西部边界向索马里(索科特拉海峡和西南路径)和也门-阿曼海岸(西北路径)出口需要一到三年的时间。相比之下，到达东部边界所需的时间要长得多。在北纬14°以北，最频繁的时间约为10-15年，在阿拉伯海东南部约为20-25年。因此，RSOW通常可以将氧气带到西部边界，但不能带到东部盆地。这可能有助于阿拉伯海氧气最低限区的东移，这是一个值得调查的问题。
The present study investigates the advective pathways and transit times of virtual particles released in the Red Sea outflow area as a proxy for the poorly understood spreading of the Red Sea Overflow Water (RSOW) in the Arabian Sea. This work uses the Parcels toolbox, a Lagrangian framework, to simulate tens of thousands of trajectories under different initial conditions. Six different Lagrangian simulations are performed at isobaric and isopycnal surfaces within the RSOW layer. All simulations are based on the eddy-rich GLORYS12 reanalysis that merges almost all in-situ (temperature–salinity) and satellite observations collected over the last two decades into a dynamical framework. This study shows that GLORYS12 reproduces relatively well the climatological seasonal cycle of the RSOW to the Gulf of Aden and essential characteristics of the exchange at the Strait of Bab al-Mandab. Statistical comparisons between synthetic trajectories and RAFOS floats in the Gulf of Aden corroborate the quality of GLORYS12 velocity fields used for the Lagrangian simulations. Six main advective pathways are uncovered (by order of preference): Southwest, Northwest, Socotra Passage, Central, Eastern, and Southern. Trajectories from Argo floats give observational support for some of these paths. Although most particles are exported out of the Arabian Sea off Somalia, the simulations reveal robust connectivity of the RSOW to the Arabian Sea interior and its eastern boundary. The fact that particles have long trajectories in the interior increases the potential of RSOW mixing with the fresher and oxygen-poor ambient waters. Thus, these pathways may have profound implications for the salt and oxygen budgets in the Arabian Sea and beyond since the RSOW is also part of the global overturning circulation and exported out of the Indian Ocean via the Agulhas Current. Transit time distributions indicate that it takes about six months for outflow-originated particles to spread over the entire Gulf of Aden and one to three years to be exported along the western boundary, toward Somalia (Socotra Passage and Southwest pathways) and off the Yemeni–Omani coast (Northwest Pathway). In contrast, reaching the eastern boundary takes much longer. North of 14° N, the most frequent time is around 10–15 years, and about 20–25 years at the southeastern Arabian Sea. Hence, the RSOW can often carry oxygen to the western boundary but not to the eastern basin. This may contribute to the eastern shift of the Arabian Sea Oxygen Minimum Zone, a subject that deserves investigation.