Impact of East Asian winter monsoon on rainfall over southeastern China and its dynamical process

Abstract

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.

Changes in precipitation and extreme precipitation in a warming environment in China

“…The weakened EAWM further weakens the control of its related cold-dry air over East Asia, favouring the northward flow of warm-moist air from low latitudes and the ocean. Consequently, in a weaker EAWM year, there is more winter precipitation over China, in particular over southern China [22,23]. These results are consistent with the distribution of winter precipitation and extreme precipitation associated with climate warming in China.…”

Long-term change in rainfall distribution in Northeast Thailand: will cropping systems be able to adapt?

“…Increased dry season rainfall in NET was found to be consistent with wider on-going climate dynamics observed in East Asia and explained by the weakening of the East Asian winter monsoon (Zhou, 2011). These changes were attributed to global warming (Zhang et al, 2011), indicating that rainfall is likely to continue increasing in the future.…”

Interdecadal Change of Winter Precipitation over Southern China in Late 1990s

“…Most studies on the effect of ENSO on East Asian summer rainfalls concentrated on spring and summer. However, the effect of ENSO on East Asian rainfall is not limited to summer only (Zhang et al 1999;Wang et al 2000;Chen et al 2009;Zhou and Wu 2010;Zhou 2011). Zhang and Sumi (2002) reported that positive precipitation anomalies were strengthened in winter (December-January-February) in southern regions of China during the El Niño mature phase.…”