Spatial and temporal characteristics of aridity index and association with AO and ENSO in Qinghai Province

This study were used the methods of climate tendency rate, spatial analysis, Penman-Monteith model, the temporal-spatial variations, cross wavelet and wavelet coherence to analyze the spatial and temporal variations of AI (aridity index), influencing factors, and the relationship of the AI with AO (Arctic Oscillation) and ENSO (El Nino-Southern Oscillation), based on the data of 29 meteorological stations in Qinghai Province during the period of 1961-2013. The results showed that the average of AI was 0.49 for many years. The trend of AI fluctuantly reduced in the past 53 years. The average of AI linearly decreased at the rate of -0.03·10 a-1 (α=0.01) over the study area, which means the climate gradually changes to moist in Qinghai Province. The maximum value and minimum value of AI appeared in December and August, respectively, which showed that the average of AI increased firstly then reduced within a year. The maximum of the AI appeared in northwest of Mangai County and north-central of Golmud City and Nuomuhong Town, and the minimum of AI appeared in southern-central of Maqulai County and Jiuzhi County. The average of AI had significantly positive correlation to sunshine time (P<0.01) and wind velocity (P<0.05) in Qinghai Province. At the same time,the average of AI has negative correlation with the temperature, precipitation and relative humidity. In addition, the average of AI is multi-scale significant correlation to AO and ENS in this study (a=0.05).