With intensification of climate change and human activities, warming and drying trend has brought severe challenges to pastoral areas in arid and semi-arid regions. Consequently, it becomes imperative to explore non-stationarity features of drought in such regions. In this research, the SPEIbase v2.4 datasets with a 0.5 degree spatial resolution was employed to extract Standardized Precipitation Evapotranspiration Index (SPEI) in Inner Mongolia, China. We explored non-stationarity characteristics of drought using Breaks For Additive Seasonal and Trend (BFAST) method, investigated the variation characteristics of drought intensity in each time interval using intensity analysis method, and finally assessed the spatial and temporal gathering characteristics of drought with Empirical Orthogonal Function (EOF). The results showed that trend of regional drought had a tendency towards drought conditions, which is particularly significant from the year 1945 onwards in the overall Inner Mongolia. We have explored a long behavior of drought in semiarid and central regions of cold semihumid climate zone throughout the whole study period, and detected a drying trend in northeastern regions of Inner Mongolia at the latter decades. The overall drought intensity displayed an increasing trend first, which was followed by a decreasing trend, among which the extreme drought was dominant in period of 1960-1970. EOF mode1 showed that variation intensity of drought showed a not significantly increasing trend in the entire region, and the drought with high amplitude was likely to occur in the central region. EOF mode2 showed that variation intensity of drought displayed the opposite phases between the eastern and the western regions. The northeastern regions were prone to display a high amplitude of drought.
Keywords: BFAST; Drought; Gathering characteristics; Intensity; Non-stationarity.
Copyright © 2018. Published by Elsevier B.V.