Spatiotemporal Drought Variation in Midlatitude East Asia Over the Past Half Millennium

Drought is a recurring challenge, especially in the arid and semi-arid regions. Therefore, understanding its spatial and temporal variation is important for pre-disaster planning and sustainable water resource management during drought. However, the sparse and short length of the instrumental records in midlatitude East Asia hampered the full understanding of drought variation, especially at multidecadal and longer timescales. Here, we compiled a tree-ring network of 364 chronologies in midlatitude East Asia and reconstructed the variation of the averaged May-August Standardized Precipitation Evapotranspiration Index at a spatial resolution of 0.5 degrees x 0.5 degrees, for the period 1501-2000 CE. The reconstruction captured the spatial and temporal variation of actual drought well and has a strong association with a drought atlas that was derived from historical documents. The study area has experienced an expansion of dry areas during the past decades; however, it is still within the natural variability of the past half millennium. According to drought variation during the instrumental period, the study area was divided into four subregions; however, running correlations showed that drought variation in some subregions was similar in past centuries, except in recent decades. This study provides new data for understanding the spatiotemporal variability of drought in midlatitude East Asia, and the vanished correlation between drought variation in some regions during the past decades indicates the complex forcing mechanism of regional drought variation. Plain Language Summary We present a 500-year drought reconstruction for midlatitude East Asia with a spatial resolution of 0.5 degrees x 0.5 degrees, by using a tree-ring network of 364 chronologies. Based on this reconstruction, we found that the recent dry area expansion in midlatitude East Asia is still within the range of natural variability of the past 500 years. Our results also showed that, except for the past several decades, the drought variation in some subregions was significantly correlated.