Analysis of future changes in meteorological drought patterns in Fulda, Germany

Meteorological droughts have large impacts on society and the environment. A better understanding and quantification of their occurrences can be highly relevant for the development of proper climate change mitigation, adaptation and resilience strategies. Here we examine meteorological droughts from observed data covering the 1971–2000 period for the Fulda catchment in Germany by means of the Standardized Precipitation Index. The joint dependency of drought duration and severity is modelled by a copula function, which relates their univariate distributions in a functional relationship. Recurrence intervals are further calculated as a function of the joint relationship and univariate marginals. Future projections are investigated in which downscaled EURO-CORDEX Regional Climate Model (RCM) projections for the period 2021–2050 are used together with the three Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5, in order to analyse and compare future joint patterns of duration and severity of events. We find that drought duration and severity present a clear interdependency supporting the choice of a bivariate model. Results suggest substantial differences in the future joint relationship duration–severity. Depending on the RCM and RCP, drought patterns show different magnitude of changes in the future. The projected changes are different for the different returns periods. RCP8.5 shows more severe events and longer drought durations than RCP2.6 and RCP4.5. The uncertainties of the projected patterns also depend on the RCP and RCM and are larger for higher return periods