Multi-decadal spatial and temporal changes of extreme precipitation patterns in northern China (Jing-Jin-Ji district, 1960-2013)

Observations of changes in daily extreme precipitation from local to global scales provide essential information for assessing the anthropogenic forcing driving natural climate. This study presents an analysis of daily precipitation records over the past half century (1960-2013) from 26 meteorological stations in northern China (Jing-Jin-Ji district) and attempts to identify spatial and temporal changes based on ten indices for extreme precipitation. Our analysis showed that all regionally averaged extreme precipitation indices were characterized by decreasing trends, of which the maximum one-day and five-day precipitation amounts (RX1day and RX5day) exhibited significant decreasing trends. We further considered possible triggering mechanisms for these trends, such as the recent continual weakening of the East Asian summer monsoon, although the detailed physical mechanisms need further study. Our analysis also showed that extreme precipitation patterns have varied spatially and exhibited a clear increasing trend from the northwest to the southeast except for consecutive dry days (CDD) and consecutive wet days (CWD). A correlation analysis showed that all indices except CDD had significant positive correlations with annual total precipitation(ATP); all indices except CDD and CWD had negative correlations with station elevation. Our results highlight the importance of understanding the patterns of changes in precipitation extremes that provide essential information for water resource management, natural hazard prevention and mitigation, and reliable future climate and environmental projections for policy makers in the Jing-Jin-Ji district. The results indicated that a higher spatial and temporal resolution analysis of extreme precipitation is needed in the study area.