The North Atlantic Oscillation signal in a regional climate simulation for the European region

Abstract

The North Atlantic Oscillation (NAO) is a dominant pattern of large-scale variability in the Northern Hemisphere, with important regional effects on the winter climate of Europe. Nested regional climate models (RCMs) can be useful tools for studying the regional signal of the NAO. Therefore, it is important to assess whether they can reproduce the observed NAO signal over Europe when driven by lateral boundary conditions from global climate models. In this paper we investigate the NAO-related winter variability over Europe in a RCM simulation driven by large-scale fields from an atmospheric global model simulation forced with historic sea surface temperature and sea ice distribution for the period 1961-1990. We show that (1) the NAO-related winter variability signal over the European region shows substantial topographically induced fine-scale features, both for temperature and precipitation, and (2) the model is capable of reproducing many aspects of this fine-scale regional signal and, in particular, the topographically forced regional response of precipitation to NAO-type circulations. We conclude that nested regional climate models can be used to study the fine-scale regional signature of the NAO under different climatic conditions. Copyright © Blackwell Munksgaand, 2005.