Respective impacts of the East Asian winter monsoon and ENSO on winter rainfall in China

Using station rainfall observations and the ERA-40 reanalysis, this study investigates respective impacts of the East Asian winter monsoon (EAWM) and El Niño-Southern Oscillation (ENSO) on winter (November-March) rainfall in China by removing the interdependence between the EAWM and ENSO using a linear regression. It is found that circulation and temperature anomalies over the tropics and midlatitude North Pacific are mainly induced by ENSO, and those over the midlatitude Asia are closely linked to the EAWM. The warm ENSO induced lower-level southwesterly winds deflect from the southeast coast of China, and thus, the influence of ENSO on winter rainfall is mainly in southern China. The lower-level southerly winds associated with a weak EAWM penetrate northward over eastern China, and thus, the EAWM influences winter rainfall in eastern China.