The present study investigates the influence of South China Sea （SCS） SST and ENSO on winter （January-February-March; JFM） rainfall over South China and its dynamic processes by using station observations for the ...The present study investigates the influence of South China Sea （SCS） SST and ENSO on winter （January-February-March; JFM） rainfall over South China and its dynamic processes by using station observations for the period 1951-2003, Met Office Hadley Center SST data for the period 1900-2008, and ERA-40 reanalysis data for the period 1958-2002. It is found that JFM rainfall over South China has a sig- nificant correlation with Nio-3 and SCS SST. Analyses show that in El Nio or positive SCS SST anomaly years, southwesterly anomalies at 700 hPa dominate over the South China Sea, which in turn transports more moisture into South China and favors increased rainfall. A partial regression analysis indicates that the independent ENSO influence on winter rainfall occurs mainly over South China, whereas SCS SST has a larger independent influence on winter rainfall in northern part of South China. The temperature over South China shows an obvious decrease at 300 hPa and an increase near the surface, with the former induced by Nio-3 and the latter SCS SST anomalies. This enhances the convective instability and weakens the potential vorticity （PV）, which explains the strengthening of ascending motion and the increase of JFM rainfall over South China.展开更多
基金supported by the National Basic Research Program of China (Grant No. 2009CB421405) the National Natural Science Foundation of China (Grant Nos. 40730952 and40905027)+1 种基金 the Program of Knowledge Innovation for the third period of the Chinese Academy of Sciences (GrantNo. KZCX2-YW-220)City University of Hong Kong Strategic Research Grants 7002231 and 7002329
文摘The present study investigates the influence of South China Sea （SCS） SST and ENSO on winter （January-February-March; JFM） rainfall over South China and its dynamic processes by using station observations for the period 1951-2003, Met Office Hadley Center SST data for the period 1900-2008, and ERA-40 reanalysis data for the period 1958-2002. It is found that JFM rainfall over South China has a sig- nificant correlation with Nio-3 and SCS SST. Analyses show that in El Nio or positive SCS SST anomaly years, southwesterly anomalies at 700 hPa dominate over the South China Sea, which in turn transports more moisture into South China and favors increased rainfall. A partial regression analysis indicates that the independent ENSO influence on winter rainfall occurs mainly over South China, whereas SCS SST has a larger independent influence on winter rainfall in northern part of South China. The temperature over South China shows an obvious decrease at 300 hPa and an increase near the surface, with the former induced by Nio-3 and the latter SCS SST anomalies. This enhances the convective instability and weakens the potential vorticity （PV）, which explains the strengthening of ascending motion and the increase of JFM rainfall over South China.
