Topography-based spatial patterns of precipitation extremes in the Poyang Lake basin, China: Changing properties and causes

The Poyang lake is the largest freshwater lake in China. Monthly precipitation extremes defined by maximum one-day precipitation amount (Rxl day) and maximum consecutive five-day precipitation amount (Rx5day) regimes were analyzed for precipitation data covering a period of 1957-2010. How the spatial patterns of these precipitation extremes are impacted by topographic characteristics was investigated using the max-stable method. Results indicated that a better performance of model can be identified if topographical influences were considered, showing the critical role of topography in the spatial distribution of precipitation extremes. Seasonal shifts of extreme precipitation events can be identified within the Poyang Lake basin: the Rxl day generally increases from the west to the east parts during spring, from the south to the north parts during summer, from the east to the west parts during autumn and from the northwest to the southeast parts during winter. Besides, details and subtle traits of spatial patterns of precipitation extremes can be attained when altitude was taken into consideration. However, complex influences of topographical properties or the mountains on changes of Rxl day and Rx5day were also detected: higher altitude tends to increase the Rxl day in summer and autumn while decrease the Rxl day in winter and spring, which should be attributed to propagation direction of water vapor flux and also different relations between water vapor flux and extreme precipitation processes during different seasons. When compared to Rx1day, the seasonal Rx5day regimes shift along the east-west direction and which may be attributed to the different seasonal movements of precipitation center for Rx5day when compared to those of Rxl day. Results of this study may help to better understand the possible influence of topography on the spatial patterns of precipitation extremes. (c) 2014 Elsevier B.V. All rights reserved.