Abstract:

To further analyze the rain intensity characteristic and trend of the hourscale precipitation,we focus on the shortterm heavy precipitation events exceeding 98% fractile.Based on the onehour precipitation data of Anhui 16 meteorological stations from 1961 to 2009,several characteristics of shortterm heavy precipitation events were analyzed in this paper,including the shortterm heavy precipitation amount,frequency,intensity,the proportion of total precipitation and the trend of daily distribution.The results showed that there was an overall increasing trend of shortterm heavy precipitation in Anhui in recent 49 years,and the increasing trend was more significant in west than in east.The MK mutation test indicated that there was an upward mutation of shortterm heavy precipitation in 2001 and even more significant mutation after 2005,which were mainly caused by the increasing frequency of shortterm heavy precipitation.In recent 49 years,78% of the Anhui total precipitation increase was derived from shortterm heavy precipitation.Furthermore,the duration of shortterm heavy precipitation had increasing trend,but there was opposite trend in the duration of total precipitation.Consequently,the contribution of shortterm heavy precipitation grew greater to the total precipitation.Meanwhile,the daily distribution of shortterm heavy precipitation exhibited a significant bimodal structure,performing the peak during the after midnightmorning and afternoondusk period.The increasing trend of the shortterm heavy precipitation amount and frequency was more significant in the morning than that in the afternoonevening.Therefore,it could be speculated that the differences of peak and trough value would be reduced,with the characteristics of Twin Peaks gradually weaken in the future