Analyses from observational datasets of various measures of extreme weather events and related processes for present-day climate in Central and Eastern Europe, using both regional as well as local datasets in participating countries as covered by the WP2 10 km simulation.

Determination of suitable percentiles of precipitation and extremes indices (WMO, STARDEX) for the validation of the present-day experiments and assessment of climate-change simulations.

Validation of present-day climate simulations with regard to extremes, based on global and regional climate simulations at scales of 50km down to 10 km. Assessment of the added value of 10km simulations in focus regions (Czech Republic, Carpathian basin, Romania, and Bulgaria).

Estimates of the effects of climate change on extreme weather events based on pre-existing GCM and RCM output as well as 10km WP2 simulations; in particular analyses of changes in droughts and heatwaves, as well as in heavy-precipitation intensity distributions, with detailed analyses in focus regions.

Process analysis of important feedbacks using sensitivity experiments; assessment of impact of model resolution and domain size on the analyzed processes.

In the first stage of the project, WP4 will focus on the analysis of extreme events in Central and Eastern Europe from observations, with the possible identification of existing trends in the recent period. Beside regional datasets (e.g. European Climate Assessment & Dataset, ECA&D), WP4 will also take advantage of the analysis of local datasets available to the individual WP4 partners (CHMI, ELU, NMA). The suitability of other datasets available from local sources will be assessed in collaboration with all WP4 partners, together with the selection of the sets of extreme indices (WMO, STARDEX) relevant for the analysis. (D4.1, D4.2)

A second focus of WP4 will be the assessment of the added value of 10km resolution for the simulation of extremes. First, existing daily model output (GCM, 50km, 20km as well as one set in 12km resolution) can be obtained through the data servers of the EU projects PRUDENCE and ENSEMBLES or from DMI. This first data stream will be used for initial analyses of realism, resolution effects and impact of model/scenario choice on the simulations. Particular consideration will be given to intensity distributions, extremes indices, as well as relevant feedback processes. Once available, the RegCM3 and Arpège European simulations delivering boundary conditions to the 10km CECILIA RCMs will be analyzed, and finally the 10km simulations themselves will be investigated, with a special focus on the Czech republic, the Carpathian basin, Romania, and Bulgaria. (D4.2, D4.3, D4.4)

Finally, WP4 will assess future trends in extreme weather events for Central and Eastern Europe, based on pre-existing GCM and RCM output as well as the 10 km WP2 simulations. This will encompass analyses of changes in droughts, heatwaves, and heavy-precipitation intensity distributions, as well as the computation of changes in related extreme weather indices as selected in D4.1. Process analyses of important feedbacks (e.g., land-atmosphere coupling) will be performed with sensitivity experiments. The impact of model resolution and domain size on the analyzed processes will be investigated, as well as the relation between the driving GCM or RCM fields and the downscaled simulations. (D4.2, D4.3, D4.4, D4.5)

Studies for the whole region will be coordinated by ETH for droughts and heatwaves and by DMI for heavy precipitation; country-based studies will be performed at local institutions in collaboration with ETH and DMI. NMA will lead the analyses for Romania, ELU and OMSZ, the analyses in the Carpathian basin, and CHMI, IAP and CUNI, the analyses for the Czech republic, NIMH will perform the analyses for Bulgaria. ICTP, ETH and CUNI will collaborate on sensitivity and process studies, with contributions from NMA.

M4.1 Month 6: Decision on which measures and indices of extremes should be part of the analyses of WP4 and detailed implementation plan resulting from D4.1
M4.2 Month 36: Finished analyses of extremes based on both pre-existing and CECILIA model output