Future Changes in Day-to-Day Precipitation Variability in Europe

We analyzed regional patterns of day-to-day precipitation variability across Europe and assessed their future changes using CORDEX regional climate models. A discrete Markov chain process was employed to calculate transition probabilities from wet and dry states and the precipitation variability was quantified using the proposed Variability index (IVAR; sum of wet-to-dry and dry-to-wet transitions divided by total number of transitions). IVAR is, in general, lowest in Southern Europe and gradually increases northward in the observed data. Performance of the regional climate models is season dependent: they capture IVAR reasonably well in summer but higher simulated variability was found for the winter season. IVAR trends computed for the 2006–2095 period suggest decreasing day-to-day precipitation variability over Southern Europe, especially in summer under the high-concentration RCP8.5 pathway. By contrast, increased variability is projected in Northern Europe. Between these two regions, future IVAR trends are less clear, because they strongly depend on the selection of driving global model, hinting of an uncertain future hydroclimate in the Central European region.