Analysis of variation of climate and potential evapotranspiration and its influencing factors in the Loess area in last 50 years

Based on the climatic data of 14 meteorological stations in the Loess area in 1951~2000,the temporal and spatial variation of the climatic variables and potential evapotranspiration were analyzed,and then the influence factors of ETo were also analyzed.The results showed that:(1) There was a temperature warming trend in Loess area in the last 50 years.The annual mean temperature had a warming rate of about 0.039~0.396℃/10a,which increased by about 0.195~1.98℃.The annual mean precipitation,wind speed,sunshine duration and relative humidity had a trend to decrease as a whole.(2) The reference crop evapotranspiration had a significant trend to increase except in Jiexiu and Zhumadian.(3) All in all,relative humidity was the most sensitive factor in the Loess area,followed by net shortwave radiation and air temperature,while wind speed had the least impact.