Understanding the oceanic response to tropical cyclones (TCs) is of importance for studies on climate change. Although the oceanic effects induced by individual TCs have been extensively investigated, studies on the oceanic response to the passage of consecutive TCs are rare. In this work, we assess the upper-oceanic response to the passage of Hurricanes Dorian and Humberto over the western Sargasso Sea in 2019 using satellite remote sensing and modelled data. We found that the combined effects of these slow-moving TCs led to an increased oceanic response during the third and fourth post-storm weeks of Dorian (accounting for both Dorian and Humberto effects) because of the induced mixing and upwelling at this time. Overall, anomalies of sea surface temperature, ocean heat content, and mean temperature from the sea surface to a depth of 100 m were 50 %, 63 %, and 57 % smaller (more negative) in the third–fourth post-storm weeks than in the first–second post-storm weeks of Dorian (accounting only for Dorian effects), respectively. For the biological response, we found that surface chlorophyll a (chl a) concentration anomalies, the mean chl a concentration in the euphotic zone, and the chl a concentration in the deep chlorophyll maximum were 16 %, 4 %, and 16 % higher in the third–fourth post-storm weeks than in the first–second post-storm weeks, respectively. The sea surface cooling and increased biological response induced by these TCs were significantly higher (Mann–Whitney test, p<0.05) compared to climatological records. Our climatological analysis reveals that the strongest TC-induced oceanographic variability in the western Sargasso Sea can be associated with the occurrence of consecutive TCs and long-lasting TC forcing.

中文翻译：

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海洋对萨加索海连续的飓风Dorian和Humberto（2019）的反应

理解海洋对热带气旋的反应对气候变化研究至关重要。尽管已经对各个TC引起的海洋效应进行了广泛研究，但很少有人研究连续TC的通过对海洋的影响。在这项工作中，我们使用卫星遥感和建模数据评估了对2019年飓风Dorian和Humberto越过西部Sargasso海的上洋响应。我们发现这些缓慢移动的TC的综合作用导致了Dorian飓风后第三和第四周的海洋响应增加（考虑了Dorian和Humberto的影响），这是因为此时发生了混合和上升。总体而言，海面温度，海洋热量含量，在风暴之后的第三至第四周，海面至100 m深度的平均温度分别比风暴后的第一至第二周低50％，63％和57％（负值更大）（仅考虑Dorian效应）。对于生物学反应，我们发现表面的叶绿素 a（chl  a）浓度异常，富营养区的平均chl  a浓度和深叶绿素最大值中的chl a浓度在暴风雨后的第三至第四周分别比分别高出16％，4％和16％。风暴后的第一到第二周。与气候记录相比，这些TCs引起的海面降温和增加的生物响应显着更高（Mann-Whitney检验， p <0.05）。我们的气候分析表明，在Sargasso海西部最强的TC引起的海洋变化可能与连续TC的发生和持久的TC强迫有关。