Trends of sea surface temperature and sea surface temperature fronts in the South China Sea during 2003-2017

The trends of the sea surface temperature (SST) and SST fronts in the South China Sea (SCS) are analyzed during 2003-2017 using high-resolution satellite data. The linear trend of the basin averaged SST is 0.31 degrees C per decade, with the strongest warming identified in southeastern Vietnam. Although the rate of warming is comparable in summer and winter for the entire basin, the corresponding spatial patterns of the linear trend are substantially different between them. The SST trend to the west of the Luzon Strait is characterized by rapid warming in summer, exceeding approximately 0.6 degrees C per decade, but the trend is insignificant in winter. The strongest warming trend occurs in the southeast of Vietnam in winter, with much less pronounced warming in summer. A positive trend of SST fronts is identified for the coast of China and is associated with increasing wind stress. The increasing trend of SST fronts is also found in the east of Vietnam. Large-scale circulation, such as El Nino, can influence the trends of the SST and SST fronts. A significant correlation is found between the SST anomaly and Nino3.4 index, and the ENSO signal leads by eight months. The basin averaged SST linear trends increase after the El Nino event (2009-2010), which is, at least, due to the rapid warming rate causing by the enhanced northeasterly wind. Peaks of positive anomalous SST and negatively anomalous SST fronts are found to co-occur with the strong El Nino events.