冬半年南支槽与乌江流域汛期径流的关系探讨  

Relationship between wintertime southern branch trough and runoff of Wujiang basin in flood period

作　　者：张亮 荣艳淑[1] 魏佳[1] 胡玉恒 

机构地区：[1]河海大学水文水资源学院,南京210098

出　　处：《气象科学》2017年第6期766-775,共10页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(51420105014);国家"十三五"重点研发计划项目(2016YFA0601504);中国南方电网有限责任公司科技项目(K-ZD2014-014)

摘　　要：基于1954—2014年乌江流域站点的逐月径流与NCEP/NCAR的逐月位势高度、风矢量资料、比湿及垂直速度资料,采用相关分析、回归分析、合成分析等方法,研究了冬半年南支槽与汛期乌江流域径流的关系,并探讨了其对乌江流域径流影响的可能机制。结果表明,冬半年各月南支槽强度指数(Southern Branch Trough Index,SBTI)与5月乌江流域径流有着稳定且显著的负相关关系,且基于冬半年月份SBTI构建的线性回归模型可以很好地预测5月径流;因此,冬半年南支槽指数可以作为乌江流域5月径流的预报因子。合成分析表明,南支槽强年,青藏高原南侧西风带波动强烈,且槽前风场差值呈气旋性异常,伴随着乌江流域的南风矢量,为槽前暖湿气流向乌江流域的输送提供了水平动力;副热带高压强度的减弱可能使得来自西太平洋的水汽流向乌江流域,强化了水汽向乌江的输送;南支槽强年乌江流域低层到高层水汽含量显著增加,垂直上升运动可持续到300 h Pa,加强了乌江流域的水汽辐合和对流运动,有利于该流域降水的产生,进而使得径流量显著增加。By using the methods of correlation, regression and composite analysis, the relationship between the runoff of Wujiang Basin in flood season and the Southern Branch Trough （SBT） were re- searched, the physical mechanism were discussed as well. The runoff were acquired from hydropower sta- tions in Wujiang Basin, and the meteorological data including geopotential height, vector wind, specific humidity and vertical speed are obtained from NCEP/NCAR, the time range for all the data is 1954-- 2014. It indicates that Southern Branch Trough Index（SBTI） in wintertime is significantly and stably cor- related to the runoff of Wujiang Basin in May. The streamflow of Wujiang in May can be effectively simu- lated by using the linear regression model, and the SBTI, therefore, may be served as a reliable factor for predicting the runoff of Wujiang. According to the result of composite analysis, in strong years of SBTI, westerlies fluctuates dramatically in southern part of Tibetan Plateau, meanwhile, cyclonic anomaly of wind field can be found in front of the trough with the south wind vector occurring in Wujiang Basin,which provides horizontal power for process of water vapor delivery in Wujiang. The decrease in terms of intensity for western Pacific subtropical high can result in transportation of water vapor to Wujiang Basin, which would strengthen the process correspondingly. In strong year of SBTI, the content of water vapor has a significant increasing from the lower to upper level of troposphere in Wujiang, upward movement of airflow is sustainable at 300 hPa and accelerates moisture convergence in the basin. This will promote the generation of precipitation in this area and eventually cause a remarkable increasing of runoff.

关 键 词：南支槽 径流 合成分析 乌江流域 

分 类 号：P434[天文地球—大气科学及气象学]