Decadal change in ENSO related seasonal precipitation over southern China under influences of ENSO and its combination mode

Abstract

Existing researches have suggested that the meridionally quasisymmetric El Nino/Southern Oscillation (ENSO) mode and the antisymmetric combination mode (C-mode; reflecting the nonlinear atmospheric interaction between ENSO variability and the annual cycle) can significantly influence the seasonal precipitation over southern China during the boreal winter and spring. By using atmospheric reanalysis data and gridded precipitation observations, this study demonstrates that these influences have an obvious decadal change in their impact intensity and in the region over southern China around 2000, coincident with the climate shift that occurred over the tropical Pacific after the late 1990s. The precipitation anomalies dominantly influenced by ENSO mode shifted from southern China in winter during the 1980s–1990s to the Yangtze River Valley in spring after the 2000s. Additionally, the precipitation anomalies independently affected by C-mode were concentrated over southern China in spring, and their effects were further enhanced in the 2000s–2010s. The direct contribution of ENSO mode to southern China’s precipitation has declined. This decadal change in seasonal precipitation is largely due to different types of ENSO (eastern-Pacific/central-Pacific) accompanied by different atmospheric circulations over the western North Pacific (WNP) associated with C-mode responses. The understanding of this climate shift in the influences of ENSO mode and C-mode on affecting the seasonal precipitation over southern China indicates a potential opportunity for improving the ENSO mode/C-mode-related precipitation predictions over southern China.