1961-2011年秦巴山区极端降水事件的时空特征分析  

Spatiotemporal Characteristics of Precipitation Extremes in the Qinba Mountains Region during 1961-2011

作　　者：杨波[1] 张勃[1] 安美玲[1] 张调风[1] 

机构地区：[1]西北师范大学地理与环境科学学院,兰州730070

出　　处：《水土保持研究》2014年第1期110-116,共7页Research of Soil and Water Conservation

基　　金：国家自然科学基金项目(40961038);生态经济学省级重点学科项目(5001-02);西北师范大学知识与科技创新工程项目(NWNU-KJCXGC-03-66)

摘　　要：利用1961—2011年秦巴山区及其周边36个站点的逐日降水数据,应用百分位阈值定义法、线性倾向估计法和Morlet小波周期和小波方差分析,通过区域划分探讨秦巴山区极端降水事件的时空特征。分析表明:秦巴山区极端降水阈值在空间上自东南向西北递减;极端降水发生频数与年均降水日数分布情况相似,自东向西依次增大;年均降水量、年均极端降水量空间分布特征相似,中部值最高,而西部地区的极端降水比重最高,达到44%。极端降水的发生频数受降水日数多少的制约,受地形影响更加显著。极端降水事件发生频数在东部、中部和全区呈不显著上升趋势;西部地区为不显著下降趋势;在20世纪80年代中期有一个明显的峰值,90年代中后期上升幅度较大,而西部地区变化幅度最小。通过Morlet小波和小波方差分析得出,整个秦巴山地区的准周期相似,在32a左右振荡最强,为第1准周期,还有12a和17a的第2准周期。此外,秦巴山地区极端降水事件的发生可能受西南季风影响较大。The Qinba Mountains covering the southeastern part of Gansu province, southern part of Shaanxi and partial Sichuan was considered. The present study focused on the analysis of the spatiotemporal charac- teristics in daily extreme precipitations indices at a regional scale over 51 years （1961-2011）, while the in- dex threshold is defined at 95th percentile and the linear least square method, Morlet wavelet analysis was used for the analysis. The distribution of extremely wet days in the area is regular and frequencies in western stations are more than eastern stations and southern stations are more than the northern those calculated for. Positive slopes were found in middle and eastern part of the Qinba Mountains in case of extremely wet days while the western part presented a positive slope, also, the positive slopes were detected in the whole region on an average level but all of the calculated slopes of extremely wet days are statistically insignificant. By Morlet wavelet and wavelet variance analysis, similar to the quasi periodic Qinba mountain area, around 32 a oscillation is strongest, as first quasi cycle. In addition, the extreme precipitation events in this area may be influenced more by southwest monsoon.

关 键 词：秦巴山地 极端降水 时空变化 MORLET小波分析 

分 类 号：P426.6[天文地球—大气科学及气象学]