Extreme precipitation event over the Yellow Sea western coast: Is there a trend?

Abstract

Based on dataset at 12 meteorological stations across the Yellow Sea western coast (YSWC) during 1951–2011, spatiotemporal variations of extreme precipitation events are analyzed by the methods of linear regression, Mann–Kendall test and wavelet analysis. Results show that the majority of precipitation indices exhibit decreasing trends excepting for consecutive dry days (CDD) and simple daily intensity index (SDII), which display increasing trends in most of locations, indicating that the rainfall becomes more concentrated and the intensity of precipitation increases in the last decades. Trends in extreme precipitation indices have mixed patterns over the intersection regions between Shandong and Jiangsu, where the increases in drought-flood disasters may be dramatic. Regional extreme precipitation indices in CDD and SDII show significant positive trends even though the annual total wet day precipitation (PRCPTOT) has a significant decline trend, this suggests that the increases in intensity of precipitation cannot counteract the decreases in other wet-related indices and the YSWC tends to be drier conditions. The temporal variability in seasonal indices of max 1-day precipitation (RX1day) and max 5-day precipitation (RX5day) shows that winter is becoming the wettest season. And the abrupt shift of precipitation regime in the later 1970s is detected for several indices. Factor analysis indicates that the changes in precipitation extremes, rather moderate rainfall, are of great contributions to the variability of annual total rainfall. There are multiple and overlapping cycles for most precipitation indices during 1951–2011, suggesting variations of time and frequency, while the 12–15-year cycle is prevailing for some indices. Further analyses indicate that global warming, coupled ocean-atmosphere phenomena, and urbanization are three major forcing factors affecting the variations in precipitation extremes over the YSWC during last decades.