Global Projections of Changes in Köppen-Trewartha Climate Zones Derived from RegCM CORDEX-CORE Simulations

The analysis of climate patterns can be performed for each climatic variable separately or the data can be aggregated using e.g. a kind of climate classification. The advantage of such method, in our case K ö ppen-Trewartha classification, is putting together the most important variables, i.e. temperature and precipitation, considering not only annual means, but through monthly values the annual cycle as well. These classifications usually correspond to vegetation distribution in the sense that each climate type is dominated by one vegetation zone or eco-region. C limate classifications represent a convenient tool for the assessment and validation of climate models and for the analysis of simulated future climate changes.

The results of RegCM driven by selected CMIP5 simulations (mostly HadGEM, MPI and NorESM) produced within the CORDEX-CORE experiment over nine CORDEX domains are analysed. Validation based on ERA-Interim driven runs compared to CRU database (E-OBS for higher resolution in Europe) shows some systematic biases in different types. Through the analysis of the control experiments together with the performance of driving GCMs we can assess the sources of biases in present conditions as well as the added value, which comes mainly from better description of topography in higher resolution and thus appearance of mountainous tundra type, as well as better representation of coastal regio ns and thus separating maritime subtypes. Finally, for two scenarios RCP8.5 and RCP2.6 we show the projections of the individual type areas, individual transformations of types or their shifts in CORDEX domains (e.g. decrease of boreal and tundra type area, their shift to the higher latitudes and altitudes, increase of temperate climate, deserts, savanna, more significant for RCP8.5). We compare the changes with the signal of climate change for driving GCMs to identify the added value of higher resolution RCM simulations.