Investigation of long-term variability and conditions for formation of precipitation in the Selenge River basin
The factors influencing on rainfall production in the Selenge River basin are investigated, using observational data about atmospheric precipitation, surface air temperature, and NCEP/NCAR Reanalysis 1 data about vertical velocity and precipitable water vapor. The contribution of each of rainfall forming factors and relationships between them are defined. Combinations of the most favorable and unfavorable factors for precipitation in the investigated region are revealed. The long-time variations of the total rainfall and rainfall forming factors are investigated for period 1948–2010 in the Selenge River basin. The intervals with different rainfall forming conditions are showed. It was found that the main reason of precipitation decrease observed in recent decades is the atmospheric moisture content decrease caused by reduction in East Asian of the summer monsoon moisture transport.