Extreme 2020 summer SSTs in the northern South China Sea: implications for the Beibu Gulf coral bleaching
Extreme 2020 summer SSTs in the northern South China Sea: implications for the Beibu Gulf coral bleaching
复制标题
2020年夏季南海北部极端海温：对北部湾珊瑚白化的影响
作者：
Yicheng Chen;Fangguo Zhai;Peiliang Li;Yanzhen Gu;K. Wu
于二零二零年夏季，北部湾发生严重珊瑚白化事件。这次事件是由南海北方破纪录的暖海温异常引起的。南海异常反气旋（AACs）与印度洋变暖有关，拉尼娜现象导致了南海极端变暖。2020年5月至7月，热带西太平洋上空出现了异常的反气旋切变东风，这是对印度洋变暖的开尔文波反应。这些东风通过Ekman动力学导致了NSCS和热带西北太平洋上空的AAC。此外，异常东风增加了从太平洋到海洋大陆（MC）的水汽通量，增强了MC对流，从而通过异常Hadley环流支持了NSCS AAC。在这一阶段，增加的入射短波辐射引起的NSCS AAC是主要贡献者的NSCS变暖。2020年9月，与拉尼娜现象相关的赤道太平洋东风异常可能通过增强MC对流触发NSCS AAC。AAC主要通过增加向下潜热通量和短波辐射使南海海温异常增温。与NSCS AAC相关的向下热平流也有助于NSCS的极端变暖。
A severe coral bleaching event occurred in the Beibu Gulf during boreal summer 2020. This event was caused by record-breaking warm sea surface temperature (SST) anomalies in the northern South China Sea (NSCS). Anomalous anticyclones (AACs) over the NSCS linked to the Indian Ocean warming and La Niña induced the extreme NSCS warming. In May through July 2020, anomalous anticyclonic-shear easterlies appeared over the tropical western Pacific as a Kelvin wave response to the Indian Ocean warming. These easterlies resulted in an AAC over the NSCS and tropical northwestern Pacific via the Ekman dynamics. Besides, the anomalous easterlies increased moisture fluxes from the Pacific to the Maritime Continent (MC), enhancing the MC convection and thus supporting the NSCS AAC via an anomalous Hadley circulation. In this stage, the increased incident shortwave radiation induced by the NSCS AAC was the major contributor to the NSCS warming. In September 2020, anomalous equatorial Pacific easterlies associated with the La Niña could trigger an NSCS AAC by enhancing the MC convection. The resultant AAC warmed the NSCS SST anomalies mainly by increasing downward latent heat flux and shortwave radiation. Downward heat advection associated with the NSCS AAC also contributed to the extreme NSCS warming.