Summer surface salinity variability in the Yellow and East China Seas: ENSO effects

Abstract

The Yellow and East China Seas (YECS) show interannual variability in both physical and biological aspects in relation with El Ni&ntilde o&#8211 Southern Oscillation (ENSO). We investigate the interannual variability of summer sea surface salinity (SSS) in the YECS and its linkage with ENSO, using a global ocean general circulation model (OGCM) with a regional focus on the YECS. The OGCM experiment reveals that the dominant interannual variability of the SSS in the YECS is attributed to a variability of the Changjiang river discharge (CRD). The variability of the CRD is linked to ENSO-related precipitation over the Changjiang river when El Ni&ntilde o events occur in winter, precipitation over the Changjiang river increases in the rainy season of the following years. The increased precipitation in El Ni&ntilde o years results from enhanced southwesterly moisture flux from the South China Sea into southern China. In addition to salinity variability, increased CRD in El Ni&ntilde o years tends to increase CHL-a concentration by supplying more nutrients into the YECS, suggesting that the ENSO-related variability of CRD is likely to affect biological production in the YECS. Our finding suggests that ENSO contributes to interannual variability of both physical and biological processes in the YECS by modulating CRD through precipitation changes over the Changjiang river.alinity (SSS) in the YECS and its linkage with ENSO, using a global ocean general circulation model (OGCM) with a regional focus on the YECS. The OGCM experiment reveals that the dominant interannual variability of the SSS in the YECS is attributed to a variability of the Changjiang river discharge (CRD). The variability of the CRD is linked to ENSO-related precipitation over the Changjiang river when El Ni&ntilde o events occur in winter, precipitation over the Changjiang river increases in the rainy season of the following years. The increased precipitation in El Ni&ntilde o years results from enhanced southwesterly moisture flux from the South China Sea into southern China. In addition to salinity variability, increased CRD in El Ni&ntilde o years tends to increase CHL-a concentration by supplying more nutrients into the YECS, suggesting that the ENSO-related variability of CRD is likely to affect biological production in the YECS. Our finding suggests that ENSO contributes to interannual variability of both physical and biological processes in the YECS by modulating CRD through precipitation changes over the Changjiang river.