In this case, the initial and lateral boundary conditions including the lower boundary were taken from ERA-Interim re-analysis. This experiment is later referred to as the ‘uncoupled run’. Coupled COSMO-CLM and NEMO: The atmospheric

and ocean models were run together in the coupled mode and exchanged information. At the two lateral boundaries of NEMO, temperature and salinity were prescribed by Levitus climatology data (Levitus et al., 1994 and Levitus and Boyer, 1994). At the upper boundary of the ocean model, atmospheric forcing was taken from COSMO-CLM. The COSMO-CLM model, on the other hand, received forcing from NEMO at its lower boundary. This experiment is later referred to as the ‘coupled run’. The ocean and sea-ice model was spun up in stand-alone mode from January 1961 to December Cetuximab clinical trial 1978. After that, both atmospheric and oceansea-ice models were spun up from 1979 to 1984 in the coupled mode. The simulations which were used for evaluation start from 1985. Since the COSMO-CLM and NEMO models were coupled for the North and the Baltic Seas for the first time, we assessed the coupled system by comparing its results with the uncoupled COSMO-CLM run. In addition,

we also evaluated the coupled model performance by using E-OBS data (Ensembles daily gridded observational dataset for temperature in Europe, version 8.0) (Haylock et al. 2008). The dataset was available daily Selleck DAPT on a 0.50° regular latitude-longitude grid, covering the whole domain of our coupled model. The period of evaluation is from 1985 to 1994 within the available period of E-OBS data (1950–2012) and of ERA-Interim (1979–2012). Results are considered for eight sub-regions as already used in the PRUDENCE projects and described by Christensen & Christensen (2007). Region 9 encompasses all eight sub-regions as shown in Figure 1b. The coupled model’s SST was evaluated against SST data from Advanced Very High Resolution Radiometer (AVHRR)

(Reynolds et al. 2007). This gridded SST analysis is provided on a daily base with a resolution of 0.25° using satellite data and in situ data from ships and buoys. When comparing the coupled and uncoupled systems, we expected differences in the results due to the active interaction HA-1077 research buy between atmosphere and ocean-ice in the coupled model. To examine the cause of the possible differences, we determined the main wind direction over the study period by adapting the weather classification method from Bissolli & Dittmann (2001). Bissolli & Dittmann (2001) presented an objective weather type classification for the German Meteorological Service. Their study area was an extended central European area (Figure 1 in Bissolli & Dittmann (2001)). Since those authors focused on Germany, the area of Germany was given higher weighting (factor three), compared to the surroundings (weighting factor two) and the rest of the area (weighting factor one).