Documentary and instrumental-based drought indices for the Czech Lands back to AD 1501

This study addresses the reconstruction of 4 slightly different drought indices in the Czech Lands (now the Czech Republic) back to 1501 AD. Reconstructed monthly temperatures for Central Europe that are representative for the Czech territory, together with reconstructed seasonal precipitation totals from the same area, are used to calculate monthly, seasonal and annual drought indices (SPI, SPEI, Z-index, and scPDSI). The resulting time series reflect interannual to multi-decadal drought variability. The driest episodes cluster around the beginning and end of the 18th century, while 1540 emerges as a particularly dry extreme year. The temperature-driven dryness of the past 3 decades is well captured by SPEI, Z-index and scPDSI, whereas precipitation totals show no significant trend during this period (as reflected in SPI). Data and methodological uncertainty associated with Czech drought indices, as well as their position in a greater European context, are critically outlined. Comparison with fir tree-rings from southern Moravia and a spatial subset of the 'Old World Drought Atlas' (OWDA) reveals statistically significant correlation coefficients, of around 0.40 and 0.50, respectively. This study introduces a new documentary-based approach for the robust extension of standardised drought indices back into pre-instrumental times, which we also believe has great potential in other parts of the world where high-resolution paleoclimatic insight remains limited.