Relationship between wintertime southern branch trough and runoff of Wujiang basin in flood period
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 researched,the physical mechanism were discussed as well.The runoff were acquired from hydropower stations 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 correlated to the runoff of Wujiang Basin in May.The streamflow of Wujiang in May can be effectively simulated 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.
国家科技期刊平台
NSTL
万方数据
维普
