Classifications and Characteristics of Marine Heatwaves in the Northern South China Sea

Yinxia Wang,Yinghui He,Zheng Wei,Jisheng Zeng,Song Tian,Qidong Chen,Fan Yang,Shan Li

doi:10.3389/fmars.2022.826810

Abstract

The classifications and associated characteristics of marine heatwaves (MHWs) in the northern South China Sea (SCS) have been investigated. Based on the ratio of the area with MHWs to the total area of the northern SCS, the MHWs are divided into three categories, i.e., narrow coverage, moderate coverage, and wide coverage. Different kinds of MHWs (i.e., narrow coverage, moderate coverage, and wide coverage) contribute around 64, 28, and 8% to the total days with MHWs, respectively. Narrow coverage MHW scatters over the northern SCS continental shelf, and moderate (wide) coverage MHWs are concentrated east of Hainan Island (mid of northern SCS continental shelf). Wide coverage MHWs contribute more than 50% to the total MHW cumulative sea surface temperature (SST) anomalies. The cumulative days and temperature anomalies of all kinds of MHWs exhibit significant long-term trends and decadal variability.

Highlights

Marine heatwave (MHW) is defined as an anomalously warm, discrete, and prolonged event, which has drawn great attention due to its extraordinary influences on ecosystem structure and functioning (Wernberg et al, 2013; Hobday et al, 2016; Gao et al, 2020)
Moderate coverage MHWs occupy around 28%, and wide coverage is only around 8%
Using the daily ratio of the area with MHWs to the total area of the northern South China Sea (SCS) continental shelf, the MHWs are divided into three categories, i.e., narrow coverage, moderate coverage, and wide coverage

Summary

Introduction

Marine heatwave (MHW) is defined as an anomalously warm, discrete, and prolonged event, which has drawn great attention due to its extraordinary influences on ecosystem structure and functioning (Wernberg et al, 2013; Hobday et al, 2016; Gao et al, 2020). Under the influence of intensification of the western North Pacific subtropical high, upwelling in the midwestern SCS weakens and causes basin-wide severe summer MHWs. Due to the MHWs in the SCS, the symbiotic relationship between corals and algae has been disrupted (Hughes et al, 2017; FIGURE 1 | Spatial distributions of (A) the number of marine heatwaves (MHWs) in each year, (B) average MHW duration, and (C) average MHW intensity in the South China Sea during the period of 1982–2018. The significant long-term trend of MHW occurrence and intensity mainly centers in the northern SCS continental shelf and the western margin (Figures 1D–F).

Results

Conclusion