Spatial and temporal variation of extreme precipitation over the Yangtze River Basin

摘要

The present study examines the spatial and temporal variation of extreme precipitation over the Yangtze River Basin based on meteorological data for 1960-2004. From 147 stations, regional characteristics of extreme precipitation are analyzed using a rotated empirical orthogonal function (REOF). Non-parametric trend analysis and wavelet transformation analysis are applied to analyze the temporal variation of extreme precipitation. The results show that (1) 6 leading modes of extreme precipitation exist in the following area: eastorth-eastern Yangtze, north/central Yangtze, south-eastern Yangtze, north-western Yangtze, western Yangtze and south/ south-western Yangtze; (2) significant positive changes can be found for extreme precipitation averaged for the eastorth-eastern Yangtze and the western Yangtze basin, and statistically significant abruption is detected in year 1986 for both regions; (3) significant negative trends can be detected over the north-western Yangtze basin with abruption in the years 1968 and 1990; and (4) long-term trends and inter-decadal oscillations of extreme precipitation can be found for 6 mode domains, but not constant periodicity. The increase in heavy precipitation in the middle-lower reaches can partly explain the frequent occurrence of floods in the 1990s. It is difficult to predict the trends of heavy precipitation for future years, but possible alternating of high-frequency extreme precipitation in the middle and lower reaches indicates flood disaster might be aggravated in the incoming decade of the 21st century in the Yangtze River Basin.