Meteorological Drought Migration in the Poyang Lake Basin, China: Switching among Different Climate Modes

The spatiotemporal variability of droughts over a region can often be characterized by combining orthogonal climate modes with corresponding temporal coefficients. The temporal characteristics of climate modes have been extensively addressed, while their spatial development remains largely unexplored. Hence, this study investigated the spatiotemporal evolution of meteorological droughts from the perspective of climate modes. Nearly 50 years of monthly precipitation records (1960-2007) from 73 meteorological stations in the Poyang Lake basin, China, were used. The standardized precipitation index at a 1-month scale was applied to quantify meteorological droughts. The dominant modes of the droughts over the basin were identified using principal component analysis, K-means cluster analysis, and analysis of variance. Based on the trajectory migration identification method, the role of the climate modes in spatiotemporal evolution was analyzed. The results showed that four spatial modes of the droughts in the basin were identified. The spatial extents, centroids, and severity of the drought clusters based on the identified modes were significantly consistent with those based on the meteorological stations (R-2 > 0.8, p < 0.05), which indicated that these modes could mostly match the large areas where serious dry/wet conditions occurred. Moreover, their performances in characterizing the spatiotemporal evolutional features (severity, migration distance, and pattern) of drought events were valid, which indicated that they might be considered as the elementary constituents of the historical meteorological drought events across the basin. The findings might offer some implications to understand drought development and causes through possible connections between the dominant modes and climate variability.