Enhanced influence of ENSO on winter precipitation over southern China in recent decades

Abstract

AbstractUsing observation, reanalysis and model datasets, the impact of the El Niño-Southern Oscillation (ENSO) on winter precipitation in southern China is re-examined. The results show that positive correlation between ENSO and winter precipitation in southern China after 1995 is significantly higher than that before 1995. Significant positive correlation is located mainly over the southern coastal areas of China before 1995, whereas the positive correlation extends northward to the Yangtze River basin after 1995. These changes in the relationship between ENSO and winter precipitation are related to the ENSO pattern and Philippine anticyclone changes. An increasing trend is observed in the ENSO amplitude, while the area with cooler SST in the Philippine seas extends westward after 1995 compared with that before 1995, leading to an extension of the anticyclone from the east side to the west side of the Philippines. The westward extension of anticyclone after 1995 could enhance the winter precipitation over southern China through modifying water vapour fluxes and vertical motion. Model results support the observation analyses of the changes in ENSO-precipitation relationship and the corresponding mechanism. The mean SST changes could also modify the ENSO-precipitation relationship.