Changes in the spatial and temporal characteristics of China's arid region in the background of ENSO

Arid regions are sensitive to changes in precipitation, while El Niño-Southern Oscillation strongly influences worldwide hydrometeorological processes. Temporal and spatial changes of characteristics including precipitation, annual mean temperature and area in China's arid region were analyzed, using daily precipitation and temperature data from 117 meteorological stations of 1961-2016. The results show that: (1) The arid region is getting warmer and wetter. During the past 56 years, the precipitation in the arid region have shown an increasing trend. The annual and quarterly precipitation all exist a cycle of about 4 years. There is a negative correlation between the area of the arid region and the annual mean temperature, which is significant at the 0.01 level. (2) The area of arid region has been on a downward trend since 1968, and there was a mutation in 1992. There are three main cycles of 24 years, 13 years and 5 years in the area of the arid region. During the study period, the spatial center of the arid region's precipitation moved 0.14° to the north and 0.77° to the east. (3) The response of precipitation to ENSO is different between the eastern and the western arid region. El Niño events increased the area of China's arid region in El Niño years and La Niña events increased the precipitation of China's arid region in La Niña years. The response of China's arid region to ENSO in the first half of the following year is opposite and the response in spring is the most significant. To sum up, in El Niño years the eastern arid region increased in area and precipitation, while in La Niña years the western arid region decreased in area and the eastern arid region increased in precipitation, which was related to the eastward movement of the spatial center of the precipitation.