Changes in clustered extreme precipitation events in South China and associated atmospheric circulations

Abstract

ABSTRACTPrevious studies have documented that the summer precipitation over South China (SC) has experienced a prominent inter‐decadal increase in 1992/1993, and the possible mechanism has been well revealed. The aim of this study is to investigate the changes in extreme precipitation and clustered extreme precipitation events in recent decades using station observations and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. The results indicate that extreme precipitation also experienced a significant inter‐decadal increase around 1992/1993. Significant changes can also be found in the associated atmospheric circulations, such as the western North Pacific subtropical high (WNPSH) and the westerly jet stream over East Asia. In addition, the water vapour transport (WVT) related to extreme precipitation differed from mean conditions. For extreme precipitation events, the WVT from the Northwest Pacific and Indian Oceans was much stronger when compared with mean precipitation. When extreme precipitation events were clustered, the increased WVT mainly originated from the South China Sea and Northwest Pacific Ocean. Further analysis indicates that the WVT increased from the Indian Ocean but decreased from the Northwest Pacific after 1992/1993; this finding explains the significant increase in the clustered extreme precipitation events over SC after 1992/1993. In addition, the atmospheric stratification has become more unstable since 1992/1993.