Spatio-temporal variation of vapor pressure deficit and impact factors in the Yalung Zangbo River basin from 1981 to 2023
Vapor pressure deficit(VPD)reflects the atmospheric water demand,and clarifying the spatial and temporal characteristics of VPD is helpful to understand the response of regional atmospheric dryness and wetness to climate change.Based on the data of monthly sunshine duration,average temperature(Tm),average maximum temperature,average minimum temperature,precipitation(Pr),relative humidity,vapour pressure(e)and wind speed of 34 meteorological stations in the Yalung Zangbo River basin(YZRB)from 1981 to 2023,the spatio-temporal characteristics and influencing factors of VPD in YZRB during recent 43 years were analyzed by linear trend estimate,R/S analysis,Mann-Kendall method,Morlet wavelet analysis and stepwise regression method.The results show that:(1)The annual and seasonal VPD in YZRB were generally lower in the east and west,and higher in the middle.The monthly variation showed a bimodal pattern,with the 1st and 2nd peaks in June and October,respectively,and the minimum in January.VPD was the largest in summer,followed by spring,and the smallest in winter.(2)The annual VPD increased significantly with a rate of 0.030 kPa/(10 a),mainly in summer and autumn,especially in the last 23 years(2001-2023).The annual and seasonal VPD mutation occurred in the mid-to-late 2000s,and the possibility of continuous increase in the future is very high.The annual and seasonal VPD were lower in the 1980s and 1990s,especially in the 1990s.In the 2000s,due to the higher VPD in summer and winter,the annual VPD was higher.Annual and seasonal VPD were higher in the 2010s,mainly in summer and autumn.VPD had a significant 3-4 a cycle in spring,summer and autumn,2-3 a cycle in winter,and annual VPD had no significant cycle.(3)Seasonal/annual VPD had no significant linear relationship with geographical factors,but there was a very significant quadratic curve relationship between them.(4)The increase of annual and seasonal Tm was the dominant factor causing the increase of VPD.After 2004,the contribution of annual Tm and e to VPD decreased,and the role of Pr increased significantly.
Yalung Zangbo River basin(YZRB)Vapor pressure deficit(VPD)Linear trendInter-decadal changeClimate mutationCycle
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