Basin-wide responses of the South China Sea environment to Super Typhoon Mangkhut (2018)

• Published in: The Science of the total environment Vol. 731; p. 139093
• Main Authors: Liu, Shuhong, Li, Jiagen, Sun, Liang, Wang, Guihua, Tang, Danling, Huang, Ping, Yan, Hong, Gao, Si, Liu, Chao, Gao, Zhiqiu, Li, Yubin, Yang, Yuanjian
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.08.2020
• Subjects: basins; chlorophyll; Chlorophyll-a bloom; cold; cooling; dinner; environment; Multi-satellite remote sensing; overland flow; rain; salinity; Sea surface cooling; seawater; South China Sea; Super typhoon Mangkhut; surface water temperature; typhoons; wind; South China Sea; South China Sea; Chlorophyll-a bloom; Sea surface cooling; Multi-satellite remote sensing; Super typhoon Mangkhut
• DOI: 10.1016/j.scitotenv.2020.139093
• ISSN: 0048-9697; 1879-1026

Relative to the open Northwest Pacific, the basin-scale South China Sea (SCS) is smaller and semi-enclosed, and the impacts of frequent super typhoons on the entire SCS basin have yet to be fully understood. Using multi-satellite observations and reanalysis data, this study explored biophysical responses of the upper ocean of the SCS induced by a typical super typhoon, Mangkhut (2018), and their regional differences with potential mechanisms. There were three different significant-response regions in the whole SCS, as follows: (1) In the ocean area around the typhoon path, strong vertical mixing, upwelling and cooling were induced, resulting in the surface chlorophyll-a (chl-a) concentration enhancing markedly (three-fold). Particularly, asymmetric distribution of typhoon rainfall induced asymmetric sea surface salinity change over along the path the nearshore. Diurnal peak of chl-a concentration increased obviously, and the daily growth rate of chl-a sped up considerably in non-shore areas after Mangkhut's passage. (2) In the Beibu Gulf (BBG), the peripheral winds of Mangkhut caused a change in direction of the sea surface flow field, transporting the high-temperature and high-salinity surface seawater from the southeastern area to the BBG. This induced dramatic increases in sea surface temperature, salinity and height, and a decrease in chl-a, in most areas of BBG. (3) In the southwest SCS, the southwest monsoon–induced eastward offshore upwelling jet was weakened by the opposite large-scale peripheral wind vector of Mangkhut and gradually disappeared, resulting in accumulation and enhancement of chl-a in the nearshore. In addition, Mangkhut peripheral winds also intensified (weakened), shifting the cold (warm) eddy to the north (south) and blocking the horizontal eastward transport belt of the high-concentration chl-a. In general, our present work sheds light on the new evidence that a supper typhoon can cause basin-wide anomalies in the SCS, which has broad implications for marine biophysical environment. [Display omitted] •Three significant-response regions were identified by multi-satellite observations.•The daily growth rate of chl-a sped up considerably in non-shore areas.•Sea surface salinity near the shore was dominated by asymmetric typhoon rainfall.•Mangkhut-induced horizontal advection altered the environment of Beibu Gulf.•Offshore upwelling in the southwest SCS was affected by the peripheral of Mangkhut.