Spatiotemporal Variations of Reference Crop Evapotranspiration in Northern Xinjiang, China

To set up a reasonable crop irrigation system in the context of global climate change in Northern Xinjiang, China, reference crop evapotranspiration (ET(0)) was analyzed by means of spatiotemporal variations. The ET(0) values from 1962 to 2010 were calculated by Penman-Monteith formula, based on meteorological data of 22 meteorological observation stations in the study area. The spatiotemporal variations of ET(0) were analyzed by Mann-Kendall test, Morlet wavelet analysis, and ArcGIS spatial analysis. The results showed that regional average ET(0) had a decreasing trend and there was an abrupt change around 1983. The trend of regional average ET(0) had a primary period about 28 years, in which there were five alternating stages (high-low-high-low-high). From the standpoint of spatial scale, ET(0) gradually increased from the northeast and southwest toward the middle; the southeast and west had slightly greater variation, with significant regional differences. From April to October, the ET(0) distribution significantly influenced the distribution characteristic of annual ET(0). Among them sunshine hours and wind speed were two of principal climate factors affecting ET(0).