1. Air–Sea Interactions and Biogeochemical Responses to Medicane Daniel
关键词Tags: phytoplankton; marine heatwaves; vertical structure phytoplankton; marine heatwaves; vertical structure
摘要：Medican Daniel 于 2023 年 9 月 4 日至 12 日形成，是地中海历史上有记录以来最致命的风暴。在这项研究中，我们研究了海洋特征在丹尼尔药物强化中的作用以及生物地球化学特性对风暴的响应。我们的研究结果表明，丹尼尔在登陆前不久在沿海环境中增强，其特征是同时出现暖核涡流（WCE）、海洋热含量升高和中度海洋热浪（MHW），这表明海洋异常可能在有利的大气强迫下支持或调节了增强。此外，高分辨率地表水和海洋地形（SWOT）卫星的观测结果揭示了比低分辨率产品中所描绘的更大的反气旋涡流，从而进一步支持了海洋引起的增强的假设。 登陆前海上的有利条件伴随着上方大气的水汽汇聚和补给，导致该地区出现强降水。生物地球化学性质受到气旋引起的地下垂直混合和上升流的强烈影响。关注最大气旋强度附近的两个涡旋，我们发现观测到的深部叶绿素最大值的垂直位移超出了直接风驱动上升流的预期，这表明由涡旋涡度中和引发的结构等重调整的额外贡献。我们认为，这种药物破坏了涡流的内部平衡，导致水柱的大规模重组，其在 WCE 中的持续时间比在冷核涡流 (CCE) 中观察到的瞬态响应更长。
Abstract: Medicane Daniel, formed on 4–12 September 2023, stands out as the deadliest recorded storm in Mediterranean history. In this study, we investigate the role of sea features in the intensification of the medicane Daniel and the response of biogeochemical properties to the storm. Our results show that medicane Daniel intensified immediately prior to landfall in a coastal environment characterized by the co-occurrence of a warm-core eddy (WCE), elevated ocean heat content, and a moderate marine heatwave (MHW), suggesting that sea anomalies may have supported or modulated the intensification under favorable atmospheric forcing. Additionally, observations from the high-resolution Surface Water and Ocean Topography (SWOT) satellite reveal a larger anticyclonic eddy than that depicted in lower-resolution products, thereby further supporting the hypothesis of sea-induced intensification. The favorable conditions at the sea before landfall were accompanied by moisture convergence and moisture supply in the atmosphere above, leading to intense precipitation in this region. Biogeochemical properties were strongly affected by cyclone-induced subsurface vertical mixing and upwelling. Focusing on two eddies in the vicinity of the maximum cyclone intensity, we found that the observed vertical displacement of the deep chlorophyll maximum exceeds that expected by direct wind-driven upwelling alone, suggesting additional contribution from a structural isopycnal adjustment triggered by the neutralization of eddy vorticity. We propose that the medicane destabilizes the eddies' internal balance, leading to a large-scale reorganization of the water column that persists longer in the WCE than the transient response observed in the cold-core eddy (CCE).