面雨量计算方法及其在海河流域的应用

基于1961—2018年汉江流域57个国家气象站日降水观测资料，利用线性倾向估计、滑动平均等方法研究了汉江流域5个子流域极端面雨量时空分布特征，并对年最大极端面雨量（P_max）的重现期进行了拟合，结果表明：（1）汉江流域的年极端面雨量日数（D）与年极端5 d累积面雨量日数（D_5d）年均分布从上游向下游逐渐减少，年极端面雨量（R）与年极端5 d累积面雨量强度（I_5d）表现为两头多、中间少。（2）D和R年均分布在石泉以上、石泉安康和丹皇区间表现出一定的正相关，在安康丹江口和皇庄以下子流域表现出一定的反相关。（3）D、R、D_5d、I_5d等年代际分布特征较为相似，石泉以上、石泉安康、安康丹江口3个子流域呈双峰分布，皇庄以下子流域呈单峰分布，丹皇区间年代际特征不明显。（4）汉江各子流域D、R、D_5d、I_5d与年最大极端面雨量（P_max）等指数峰（谷）值出现的时间重叠性较高，表明同一子流域强降水发生频次较高（低）的年份，降水的持续性和极端性均相对较高（低），但同一年所有子流域出现持续性极端降水事件的概率不大。（5）汉江流域P_max呈逐年增大趋势。重现期在50 a以前P_max增速较快，之后增速变缓。皇庄以下子流域不同重现期内P_max及其增幅最强。

More extreme precipitation in the world's dry and wet regions

Based on the daily precipitation data of 1961—2018, the spatial and temporal distribution characteristics of the extreme area rainfall calculated by the relative threshold method in the five sub-basins of the Hanjiang River are studied by using the sliding average and linear tendency. Pearson Ⅲ distribution is used to reproduce annual maximum extreme area rainfall (P_max). The results show that: (1) The spatial distribution of mean annual extreme area rainfall days (D) and the mean annual extreme 5-day area rainfall days (D_5d) decrease from upreaches to downreaches in the Hanjiang River basin. The mean annual extreme area rainfall (R) and the mean annual extreme 5-day area rainfall intensity (I_5d) are more in upreaches and downreaches, and less in middle region. (2) There is a positive correlation between D and R in Shiquan and its upper reaches, Shiquan Ankang and Danjiangkou Huangzhuang, but it shows an anticorrelation in Ankang Danjiangkou and Huangzhuang and its lower reaches. (3) The interdecadal variations of D, R, D_5d and I_5d are similar. In Shiquan and its upper reaches, Shiquan Ankang and Ankang Danjiangkou the variation shows a double-peak distribution, and in Huangzhuang and its lower reaches it shows a single-peak distribution. The interdecadal characteristics are not obvious in Danjiangkou to Huangzhuang. (4) The peak (valley) values of D, R, D_5d, I_5d, and Pmax are consistent, which indicates that the persistent and extreme rainfall events are relatively high (low) in the year with high (low) frequency of extreme area rainfall in the same sub basin, but the probability of persistent extreme precipitation events occur in all the sub-basins in the same year is small. (5) Pmax shows an increasing trend in most sub basins. Before the return period of 50 years, Pmax increases rapidly, and then slows down. The growth rate of Pmax is the largest in Huangzhuang and its lower reaches in any return periods.