Anticyclonic Blocking Effects Over Europe from an Ensemble of Regional Climate Models in Recent Past Winters

Abstract

Anticyclonic blocking is an important factor for mid-latitude climate variability and is considered to play a key role on anomalous and extreme events. In this study we present an analysis of atmospheric blocking events on the output of a multi-model ensemble of Regional Climate Models (RCMs) simulations. The ensemble consists of a set of seven RCMs, nested on the European 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 atmospheric blocking events are examined in terms of their frequency in the RCM outputs and compared to events detected in the ERA-40 data set. The aim is to investigate the ability of the different RCMs to reproduce the anticyclonic blocking events of the forcing reanalysis fields. Related effects on daily average temperature and precipitation are studied in the model results by means of composite maps and correlation analysis. The results are then compared to observations, with the aid of similar analysis performed on the daily mean temperature and precipitation data derived from the E-OBS gridded dataset.