Design of High-Resolution Paleoclimate Simulations with the COSMO-CLM Model in the Eastern Mediterranean and Middle East

Abstract

The climate of the past in the Eastern Mediterranean and the Middle East is studied with a broad spectrum, both in time and space, with long high-quality instrumental time series, documentary information, and natural archives that are limited to a certain location and different periods. Filling the gaps in time and space for longer periods is currently only possible with Earth system or general circulation models (ESM, GCM) with relatively coarse horizontal resolutions of about 200 km. They can hardly connect potential regional climate impacts to major societal events in historical periods. Thus, the regional climate model (RCM) COSMO-CLM (CCLM) is adjusted by us to paleoclimate needs with the integration of all climate forcings (orbital, solar and volcanic forcing, greenhouse gas concentrations, and land-use changes). The RCM-simulations with 0.44° and 0.11° spatial resolution are set with present-day (1979–2019) climate simulations forced by the ERA-Interim reanalysis data and by the MPI-ESM. The MPI-ESM model run ‘past2k’ performed under the CMIP6 protocol will also be used as initial and boundary data in a transient RCM-simulation of the last 2500 years. The present-day simulations with the adjusted, fully forced CCLM have already shown promising results compared to observational and reanalysis data sets. Mean annual cycles of temperature and precipitation and increasing temperatures due to climate change can both be represented in the model. A preliminary comparison to observational and reanalysis datasets is the difference between the 0.44° and 0.11° horizontal resolution which is not found to significantly improve the performance.