Regular validation of the ocean models (in off-line mode) has played an essential role for the operation of MONCOZE. Although the time of formation and location of eddies are not always in agreement with for instance observations from satellites, it is mandatory that the models have correct forcing fields, reliable water masses, frontal locations and strength of topographic steering.  In turn, the mean and eddy kinetic energy can be realistically described (Røed and Fossum, 2004).

In the MONCOZE hindcast studies from 1998 the importance of the freshwater was tested for different combination of freshwater sources (no freshwater, only river-runoff, only Baltic Sea, river-runoff and Baltic Sea) and its impact on the dynamics in the Skagerrak/ northern North Sea (Albretsen and Røed, 2005). The results reveal that to obtain a realistic mesoscale activity in the NCC area, the single most important process to parameterize correctly, is the inflow of fresh water from the Baltic Sea. In addition, there is a potential for further improvements from using near real time direct river-runoff and nutrients measurements rather than climatology. This also includes the account of coast-fjord exchanges up along the west coast.

To obtain the reliable water mass distribution and stratification the salinity source of the Atlantic Water (AW) must be properly quantified and transported into the model domain. The inflow is predominantly topographically steered along the west slope of the Norwegian trench into the Skagerrak. A branch of AW also enters the North Sea between Shetland and Scotland. On average the magnitudes of these transports are 1.73 Sv and 0.48 Sv respectively. In this context, Skogen and Mol (2005) recently documented important impact and effect on the biochemical conditions in the North Sea and Skagerrak due to the physical state and forcing.

Two experiments, using climatology and TOPAZ boundary conditions, were conducted to examine the sensitivity to the inflowing Atlantic water. TOPAZ provides sea surface elevation, horizontal currents and hydrography (temperature and salinity) at selected depths at the lateral boundaries. In comparison to section observations it appears that when the boundary conditions from TOPAZ are used the results are slightly better, although the maximum salinity is higher than the observed (35.4 versus 35.2 psu). Moreover, the seasonal variability of the inflowing Atlantic Water looks better with TOPAZ. All in all, the downscaling from the large scale Atlantic-to-Arctic coverage within TOPAZ to the finer scale North Sea and Skagerrak coverage within MONCOZE ensure reliable open boundary conditions.  Anomalies in the oceanic state in the North-East Atlantic can thus be properly propagated eastward into the MONCOZE domain (Bertino et al., 2004).