Seasonal and interannual (ENSO) climate variabilities and trends in the South China Sea over the last three decades

摘要

We present a short overview of the long-term mean and variability of five Essential Climate Variables observed in the South China Sea over the last 3 decades, including sea surface temperature (SST), sea level anomaly (SLA), precipitation (P), surface wind and water discharge (WD) from the Mekong and Red Rivers. At the seasonal time scale, SST and SLAs increase in the summer (up to 4.2?°C and 14?cm, respectively), and P increases in the north. The summer zonal and meridional winds reverse and intensify (mostly over the ocean), and the WD shows positive anomalies. At the interannual time scale, each variable appears to be correlated with El Ni?o Southern Oscillation (ENSO) indices. Eastern Pacific El Ni?o events produce basin-wide SST warming (up to 1.4?°C) with a 6-month lag. The SLAs fall basin-wide (by up to 9?cm) during an El Ni?o event (all types), with a 3-month lag. The zonal and meridional winds strengthen (up to 4?m/s) in the north (weaken in the south) during all types of El Ni?o events, with a 3–5-month lag. A rainfall deficit of approximately 30?% of the mean occurs during all types of El Ni?o phases. The Mekong River WD is reduced by 1/3 of the mean 7–8 months after all types of El Ni?o events. We also show increasing trends of SST as high as 0.24?°C/decade and SLAs by 41?mm/decade. Increasing trends are observed for zonal wind, which is possibly linked to the phase of the Pacific Decadal Oscillation, and decreasing trends are observed for P in the north and both WD stations that were analyzed. The likely driving mechanisms and some of the relationships between all observed anomalies are discussed