In stand-alone mode, COSMO-CLM receives SST from ERA-Interim re-analysis data, whereas in coupled mode, it is forced by SST from the NEMO model over the North and Baltic Seas (over other sea areas, COSMO-CLM receives the ERA-Interim SST). Figure 6 shows the differences between SST of the coupled run and of ERA-Interim as used in the uncoupled run. These differences are given over the North and Baltic Seas only because over other seas and oceans, both experiments use the same ERA-Interim SST and thus the difference is zero. As can be seen, the SST
values produced by NEMO are lower than those from ERA-Interim data; the differences in the annual average over most parts of the North and Baltic Seas are between −0.2 and −0.6 K. the most pronounced differences occur in summer with NEMO SSTs up to about −1 K colder in the far north of the Gulf of Bothnia. Winter and autumn show weaker differences. INCB024360 manufacturer This result of SSTs from the coupled model is in good agreement with the results reported by Dieterich et al. (2013). In that work, the authors compared SSTs from their coupled RCA4 and NEMO models with a satellite-derived record (Loewe, 1996 and Høyer and She, 2011). They also found that the SSTs from their coupled model were low compared with observations, especially in summer. Looking at Figures 5
and 6, one sees that the 2-m air temperature and SST from the coupled experiment are both lower than those of the uncoupled experiment. Furthermore, SB431542 molecular weight the seasonal differences in SST follow those in 2-m temperature: the large difference
in SST corresponds to the large difference in 2-m temperature and vice versa. That implies a link between the SST of the North and Baltic Seas and the 2-m temperature as well as the impact of these marginal seas on the European climate. The low 2-m temperatures in the coupled experiment lead to a shallower mixedlayer depth; as a result, the heat capacity of the ocean’s Rolziracetam upper layer falls and the SSTs remain lower than the ERA-Interim data. As a feedback, reduced heat loss from the ocean to the atmosphere results in lower air temperatures. We classified the main wind direction over the 10-year period from 1985 to 1994 for both coupled and uncoupled experiments. The results show that the two model systems agree well on the average wind classification; therefore, only the wind rose from the coupled experiment is shown here. On Figure 7, the lines illustrate the direction where the wind comes from, the circles show the frequency of wind direction, and the colours show the wind speed corresponding to each direction and each frequency. The dominant wind direction over the 10 years is north-west with the highest frequency of about 22%; winds blowing directly from the north and west also occur for more than 10% of the time. South-westerly winds blow > 10% of the time but have a relatively low speed. In 50% of the cases, south-west winds occur at speeds < 5 m s−1 and in most cases < 10 m s−1.