冬季南海海洋热浪年际变化特征及影响因素分析

Analysis of InterAnnual Variation Characteristics and Influencing Factors of Marine Heatwaves in the South China Sea in Winter

摘要: 本文利用多源再分析和数值模式资料，分析了南海近40年间(1983~2022年)冬季海洋热浪(简称MHWs)的变化特征及影响因素。从气候态来看，冬季MHWs发生频率、持续时间和强度都有显著增加的趋势，其中南海北部是受MHWs影响最严重的区域。通过经验正交分解分析得知南海冬季MHWs自2000年后呈现突然增加的趋势。冬季MHWs的发生同样与西太副高的加强西伸密切相关，环流异常会增大南海北部潜热通量与南部的短波辐射通量，促进MHWs发生。此外，根据上层海洋温度方程的诊断分析表明，多尺度海洋、大气物理过程都对冬季MHWs有显著的影响，事件发生期间海洋内部动力过程对海温变化影响的量级与大气热强迫相当。这一点与夏季的MHWs有显著区别。此外，2018年12月至2019年1月的个例分析也表明，海洋中尺度和亚中尺度过程对MHWs有显著的调节作用。

Abstract: In this paper, multi-source reanalysis and numerical model data are used to analyze the variation characteristics and influencing factors of marine heatwaves (MHWs) in the South China Sea in win-ter during the past 40 years (1983~2022). From the perspective of climate state, the frequency, duration and intensity of MHWs in winter have a significant increase trend, and the northern part of the South China Sea is the most seriously affected area by MHWs. According to EOF analysis, winter MHWs in the South China Sea have shown a sudden increase trend since 2000. The occurrence of MHWs in winter is also closely related to the strengthening westward extension of the west pacific subtropical high, and the abnormal circulation will increase the latent heat flux in the north of the South China Sea and the short-wave radiation flux in the south China Sea, promoting the occurrence of MHWs. In addition, according to the diagnostic analysis of the upper ocean temperature equation, the multi-scale marine and atmospheric physical processes have significant effects on winter MHWs, and the influence of the ocean internal dynamic processes on SST changes during the event is com-parable to that of atmospheric thermal forcing. This is significantly different from MHWs in the summer. In addition, individual case analyses from December 2018 to January 2019 also indicate that mesoscale and submesoscale processes in the ocean have significant regulatory effects on MHWs.