Search

Anticyclonic blocking is an important factor for mid-latitude climate variability and is considered to play a key role in anomalous and extreme events. In this study we present an ana lysis of atmospheric blocking events on the output of a multi-model ensemble of regional climate model (RCM) simulations. The ensemble consists of a set of 13 RCMs, nested in the Euro- pean domain with a resolution of 50 × 50 km. All RCM simulations were driven by similar lateral boundary conditions, namely, the ERA-40 reanalysis for the period 1961−2000, as part of the European project ENSEMBLES. The aim was to investigate the ability of the different RCMs to reproduce the anticyclonic blocking events of the forcing reanalysis fields. When the atmo - spheric blocking events were examined in terms of their frequency in the RCM outputs, we found that the longitudinal dependence of the frequency in ERA-40 is reproduced by all RCMs. The composite map of the 500 hPa geopotential height for the days central to blocking episodes calculated for the RCM ensemble was found to be similar in pattern and magnitude to the respec- tive composite map from ERA-40 reanalysis. Related effects of the blocking events on daily aver- age temperature and precipitation were studied in the RCM simulations and compared with respective observational (E-OBS) and reanalysis (ERA-40) gridded data sets. The results of this process-oriented evaluation study indicated a rather good ability of the different RCMs to repro- duce the anticyclonic blocking events of the forcing reanalysis, as well as their influence on temperature and precipitation anomalies.

Modelling the effects of climate change on air quality over Central and Eastern Europe: concept, evaluation and projections Katarzyna Juda-Rezler, Magdalena Reizer, Peter Huszar, Bernd C. Kruger, Prodromos Zanis, Dimiter Syrakov, Eleni Katragkou, Wojciech Trapp, Dimitris Melas, Hristo Chervenkov, Ioannis Tegoulias, Tomas Halenka 1Faculty of Environmental Engineering, Warsaw University of Technology, 00-653 Warsaw, Poland 2Department of Meteorology and Environment Protection, Charles University, 180 00 Prague, Czech Republic 3Institute of Meteorology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria 4Department of Meteorology and Climatology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 5Department of Air and Water Pollution, National Institute of Meteorology and Hydrology, 1784 Sofia, Bulgaria 6Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 7Air Protection Unit of Ekometria, 80-299 Gdansk, Poland 8National Institute of Meteorology and Hydrology, Branch Plovdiv, 4000 Plovdiv, Bulgaria