Spatial-temporal evolutions of historical and future meteorological drought center in Beijing area, China

Drought has received increased attention due to its serious disasters and significant impacts. The drier areas usually deserve more attention, and thus the drought center, the area where high drought values aggregate in a region, was defined here. This study aims to access the the evoluations of three-dimensional (i.e., latitude, longitude, and time) drought center in both space and time over Beijing area. The observed meteorological data from 1961 to 2016 and the future data from 2031 to 2080 derived from the optimal GCM model were used to calculate the Standardized Precipitation and Evapotranspiration Index. A normalized drought comprehensive feature (NCf) was constructed using the entropy weight method to fully assess the drought, and then the threedimensional drought center, the high clustering region for NCf in a given space and time, was determined by employing the K-means algorithm. The results showed that, 80% of historical drought centers were dominated by high-grades and above. The 2000s experienced the most serious drought, with larger drought center areas and greater drought center grades. The future droughts were projected to alleviate in Beijing area, with decreased drought duration, frequency, intensity, severity, and weak drought center grade. 76% of future drought centers were predicated to be middle-grades and below. The high-grade drought centers would be less and the center areas would be smaller, although the center areas for the extreme-grade would be larger. The 2060s was projected to experience the worst drought in the future. In the northern mountainous areas, the future drought may intensify with more statistically significant changes points and more centroids of drought centers (45%) migrating there.