Variation Characteristics And Leading Factors Of Potential Evapotranspiration In Hebei From 1960 To 2017

ETo(potential evapotranspiration,ET0)is an important factor in the study of surface water circulation and water resources planning and management.Study trends in ET0 in specific areas and under specific conditions.Defining and changing the rules and characteristics,and identifying the dominant factors are of great significance for regional water resources utilization and agricultural production layout.This paper uses the China Meteorological Data Sharing Service Network to provide daily weather data from 1960 to 2017 in Hebei Province and surrounding areas.Using the Penman-Monteith formula,partial correlation analysis,sensitivity coefficient and contribution rate analysis,the characteristics of ETo change in the study area were analyzed within 58 years.Initial attempts to use the combination of qualitative partial correlation analysis and quantitative sensitivity analysis to further explore the dominant factors that cause ET0 changes.conclusion as below:1?In the past 15 and 58 years,the average annual ET in Hebei Province has shown a downward trend,and the average deceleration rate is-9.329mm/10a.The decreasing tendency rate is winter[0.026mm/10a]<spring[0.759mm/10a]<autumn[1.827mm/10a]<summer[5.836mm/10a].The spatial distribution of ET0 is from west to east and gradually decreases from north to south.Wavelet analysis shows that the ET0 changes have a 40-year main cycle and a 25-year small cycle.2.The average wind speed,average sunshine hours and relative humidity reduction rates were-0.02 m/s/a,-0.01 h/a,-0.07%/a,respectively.The increasing rates of the three temperature indicators were 0.03?/a,0.04?/a,0.02?/a.In the spatial distribution,the average wind speed shows a trend of large-small-sub-large distribution from northwest to southeast;the relative humidity shows a trend from northeast to northwest;the sunshine duration shows a downward trend from northwest to southeast in spatial distribution.The three temperature indicators have the characteristics of decreasing from south to north and from east to west.3.The absolute value of the partial correlation coefficient of each meteorological factor is in the order of sunshine hours>daily average wind speed>daily average relative humidity>daily average maximum temperature>average daily average temperature>daily average minimum temperature.In the season,the correlation coefficient of each meteorological factor in summer is higher,and the lowest in autumn.The dominant factors in spring are average wind speed,sunshine hours,maximum temperature and relative humidity.Summer is the number of hours of sunshine,maximum temperature and relative humidity,and autumn is the average wind speed,relative humidity and sunshine hours.Winter is the other five meteorological factors except the minimum temperature.4.The sensitivity of ET0 to various meteorological factors is increasing year by year.The most obvious performance is relative humidity,and the trend is 0.01/10a.The least obvious performance was the average temperature and the highest temperature,and the trend was only 0.002/10a.The contribution of meteorological factors is highest in summer and lowest in autumn.There is a big difference in the spatial distribution of dominant factors in each season.