基于多重分形的降雨时空解集研究.doc

 2010 年 3 月 JOURNAL OF SICHUAN UNIVERSITY ENGINEERING SCIENCE EDITION Mar. 2010  文章编号:1009-3087 2010 02-0026-08 基于多重分形的降雨时空解集研究 周玉良1 ，2 ，陆桂华2 ，吴志勇2 ，金菊良1 1. 合肥工业大学 土木与水利工程学院，安徽 合肥 230009;2. 河海大学 水文水资源与水利工程科学国家重点实验室，江苏 南京 210098 摘 要:为建立不同时空尺度降雨间联系，分析“淮河流域水分和能量循环试验与研究”中 Doppler 雷达测雨数据的 时空多重分形特性，估算降雨场的对流速度，实现了降雨场的时空转换。采用 2 参数对数泊松分布作为随机级联 生成子，建立基于随机级联的降雨时空多重分形解集模型，研究对数泊松分布的参数与大尺度雨强及降雨场离差 系数间关系，比较解集模型模拟和实测雷达降雨场的统计特征。结果表明，降雨近似为自相似多重分形过程，建立 的降雨时空解集模型能重现雷达观测降雨场的标度特性和保持实测雷达降雨场的统计特征。 关键词:降雨;解集;尺度转换;多重分形;随机级联 中图分类号:P33;P333. 6 文献标识码:A Study on Rainfall Space-time Downscaling Based on Multifractal Analysis ZHOU Yu-liang1 ，2 ，LU Gui-hua2 ，WU Zhi-yong2 ，JIN Ju-liang1 1. College of Civil and Conservancy Eng. ，Hefei Univ. of Technol. ，Hefei 230009，China; 2. State Key Lab. of Hydrology-water Resources and Hydraulic Eng. ，Hohai Univ. ，Nanjing 210098，China Abstract:In order to establish the relations between different scale rainfall fields，a space-time multifractal analysis on Doppler radar rainfall from HUBEX was proposed and scaling anisotropy parameters were estimated by spectral a- nalysis. The results indicated that space-time rainfall can be considered to be a self-similar multifractal process ap- proximately. The advection velocities of rainfall fields estimated through tracking techniques were adopted to rescale the time dimension to space dimension. The log-Poisson distribution with two parameters was used as stochastic cas- cade generator，and the multifractal rainfall space-time downscaling model was developed based on stochastic cascade. The relations between parameters of the log-Poisson distribution and rainfall intensity on larger scale and the coeffi- cient of variation of rainfall fields was studied，and the characteristics of simulated rainfall fields through downscaling model was compared with the radar observed rainfall fields. The results showed that the simulated rainfall fields match scaling behavior