Inter-Monthly Regional Variation And Spatiotemporal Variation Of Surface Salinity In The East China Sea And Its Adjacent Northwest Pacific

Based on 1871-2010 monthly average sea surface salinity(SSS)data and global submarine topography data,this study analyses the inter-monthly mean climatological distribution as well as the areal distribution of the annual range of SSS in the East China Sea and the adjacent Northwest Pacific Ocean.Combining with flow field and previous research,the climate state division of SSS is carried out.Besides,the inter-monthly regional variation of SSS in different regions and its influencing factors are discussed.On this basis,the temporal and spatial variation characteristics of surface salinity in the study area and the comparative analysis of characteristic points in typical climate areas are discussed.The results show that:(1)The study area can be divided into three salinity climatic zones: the continental shelf area of the East China Sea,the Kuroshio area of the East China Sea and the Northwest Pacific Ocean.In the Northwest Pacific Ocean,it can also be divided into three sub-climatic zones:?area,? area,? area,bounded by 25°N and29°N.(2)In the continental shelf area of the East China Sea,the annual SSS ranges from-3psu to 8.8psu,the inter-monthly regional variation of SSS is significant,especially at the mouth of the river.The inter-monthly variation range of feature points in this region is large,and the overall difference of SSS values at each point is great.(3)In the Kuroshio area of the East China Sea,the annual SSS variation is0.6-0.8psu in general,and the inter-monthly regional variation of SSS is small.The overall SSS of the feature points in the area is high,and the inter-monthly variation of SSS is not great.From the entrance to the exit of the Kuroshio in the East China Sea,SSS value gradually increases.(4)In the Northwest Pacific Ocean,the annual SSS variation is no greater than0.6psu in general,the inter-monthly regional variation of SSS is the smallest.The overall SSS of feature points in the area is high,and the inter-monthly variation of SSS is quite small.SSS increases with longitude at the same latitude.For the same longitude,SSS decreases with increasing latitude.(5)The contribution rate of variance of the first and second modes in the study area is 75.52%,and the law of the increase and decrease of surface seawater salinity is consistent with the law of annual range.There is an interannual cycle of 7 years and an interdecadal cycle of 13 years in the whole study area.