Regional climate modelling at the Rossby Centre

The Rossby Centre has developed and applied climate models since 1997, when the group was established. Since then three versions of the Rossby Centre’s Regional atmosphereland climate model have been released [RCA1 (Rummukainen et al., 2001), RCA2 (Jones et al., 2004) and RCA3 (Samuelsson et al., 2011)], along with two regional ocean-ice–atmosphereland coupled models, one for the Baltic (RCAO-Baltic, Döscher et al., 2002) and one for the Arctic (RCAO-Arctic, Döscher et al., 2009). This special issue documents a range of scientific studies based on the latest official RCA release; RCA3 (Samuelsson et al., 2011; Kjellström et al., 2005). A similar overview, based on RCA2 and associated models, was made in Rummukainen et al. (2004, and articles therein). Regional climate models (RCMs) have become important tools for providing detailed estimates of future climate change, to support a range of studies concerned with the regional impacts of climate change on natural ecosystems, society and even government and large utility planning (Giorgi et al., 2009; Rummukainen, 2010). Institutes that apply RCMs today act as an important link between the global climate modelling (GCM) community and local end-users. This link includes the provision of downscaled products, but also expert support in local climate and climate change issues. This proved to be important with respect to the governmental Commission on Climate and Vulnerability in Sweden, where adaptation measures, in response to potential climate change, were formulated at a national, Swedish, level (SOU, 2007). In this process, not only were RCA3 simulations used as the basis for these recommendations, but also expert advice from Rossby Centre personnel was crucial in providing an informed interpretation of the climate scenarios (Persson et al., 2007). Over the past ∼5–10 yr European RCM groups have collaborated closely in the development of a multi-model ensemble of regional climate change projections for Europe. One motivation for this was to provide climate impacts research with a range of estimates of European climate change, spanning the main uncertainties in future regional climate change. This strategy was the basis of the European Union ENSEMBLES project (van der Linden and Mitchell, 2009), where the Rossby Centre contributed simulations with RCA3 (Kjellström et al., 2011; Nikulin et al., 2011). Results based on these, and a number of other, transient RCA3 simulations covering the period 1961–2100 have