The summer standardized precipitation evapotranspiration index (SPEI) dataset for six European regions over the past millennium reconstructed by tree-ring chronologies

Abstract

ABSTRACT Accurate reconstructed series are crucial for studying the differences in regional hydroclimatic variations in Europe over the past millennium. Using hierarchical clustering analysis and stepwise regression methods, we reconstructed yearly time series of the summer standardized precipitation evapotranspiration index (SPEI) for six European regions over the past millennium. Our analysis also revealed prominent regional hydroclimatic differences in multidecadal signals over the past 500 years. For instance, in the 1500s–1570s (from the beginning of the 1500s to the end of the 1570s), drying trends were observed in northern and southeastern Europe, whereas southwestern Europe experienced a wetting trend. Moreover, drying trends were observed in northern and central Europe in the 1640s–1670s. Additionally, wetting trends were observed in western and central Europe during the 1830s–1850s, with drying trends in northern and southeastern Europe. Notably, the hydroclimatic variations in most European regions showed drying trends in the 1920s–1950s, especially in southern Europe. By utilizing large amounts of tree-ring samples and directly comparing regional hydroclimatic variations, our reconstructions provide a consistent and comprehensive dataset for further analysis. The reconstructed dataset is available at https://doi.org/10.57760/sciencedb.07215.