The present study investigates the impact of the East Asian winter monsoon (EAWM) on winter (January, February, and March, or JFM in short) rainfall over southeastern China (including South China and central eastern China) and its dynamical process by using station observations for the period 1951–2003 and the ERA‐40 reanalysis for the period 1958–2002. It is found that there is a significant correlation between interannual variations of the EAWM and JFM rainfall over southeastern China. Analyses show that in weak EAWM years southwesterly anomalies at 700 hPa dominate over South China Sea, which transports more moisture into southeastern China, favouring rainfall increase. At the same time, the East Asian westerly jet weakens and displaces southward, contributing to the increase in ascending motion over southeastern China. The air temperature over southeastern China shows an obvious decrease at 300 hPa and increase near the surface. This enhances the convective instability and weakens the potential vorticity (PV), which explains the strengthening of ascending motion and the increase in JFM rainfall over southeastern China. In addition, the EAWM has impacts independent of El Niño Southern Oscillation (ENSO) on JFM rainfall over southeastern China. Moreover, the rainfall anomalies over central eastern China are more closely related to the EAWM than that in South China. Copyright © 2010 Royal Meteorological Society

The present study investigates interdecadal variability of summer rainfall in Northwest China using station observations for the period 1951–2000 and the ERA‐40 reanalysis for the period 1958–2000. It is found that Northwest China summer rainfall experienced an obvious interdecadal increase around 1978. Analyses show that summer circulation, temperature and potential vorticity anomalies over Asia vary vastly before and after 1978. During the period 1978–2000, cyclonic and anti‐cyclonic circulation anomalies dominate over Northwest and North China, respectively. These are associated with the anomalous ascending motion over Northwest China, and their anomalous descending motion over North China. The temperature over Northwest China shows an obvious decrease at 300 hPa, but increase near the surface after 1978. This enhances convective instability, which contributes to the strengthening of ascent and the increase of summer rainfall in Northwest China during 1978–2000. Copyright © 2009 Royal Meteorological Society

Winter precipitation in Northwest China experienced an obvious interdecadal increase around 1987. Consistent increase in winter precipitation occurred in Middle Asia. This study investigates associated changes in atmospheric circulation and sea surface temperature (SST). Analyses show that winter water vapour flux and atmospheric circulation over the North Atlantic Ocean and Eurasia and SST in the North Atlantic Ocean were very different before and after 1987. During 1987–2008, a significant enhancement of tropospheric moisture convergence and ascending motion was observed over Northwest China and Middle Asia. This contributed to the increase of winter precipitation in Northwest China and Middle Asia. The wind difference field before and after 1987 features cyclones over Middle Asia and North Atlantic Ocean and anticyclones over East Asia and southern Europe‐northern Africa, signifying an obvious change in the Eurasian (EU) teleconnection pattern over middle latitudes of Eurasia. The results indicate that the Middle Asia and Northwest China were under the influence of enhanced westerlies from the North Atlantic Ocean that strengthened the water vapour transport to Middle Asia and Northwest China after 1987. Moreover, the interdecadal variability in the EU pattern is associated with the SST increase in the North Atlantic Ocean. Thus, the North Atlantic SST change is likely an important reason for the winter precipitation increase in Middle Asia and Northwest China.