Abstract
Abstract. The North-West European Shelf ocean forecasting system has been providing oceanographic products for the European continental shelf seas for more than 15 years. In that time, several different configurations have been implemented, updating the model and the data assimilation components. The latest configuration to be put in operation, an eddy-resolving model at 1.5 km (AMM15), replaces the 7 km model (AMM7) that has been used for 8 years to deliver forecast products to the Copernicus Marine Environment Monitoring Service and its precursor projects. This has improved the ability to resolve the mesoscale variability in this area. An overview of this new system and its initial validation is provided in this paper, highlighting the differences with the previous version. Validation of the model with data assimilation is based on the results of 2 years (2016–2017) of trial experiments run with the low- and high-resolution systems in their operational configuration. The 1.5 km system has been validated against observations and the low-resolution system, trying to understand the impact of the high resolution on the quality of the products delivered to the users. Although the number of observations is a limiting factor, especially for the assessment of model variables like currents and salinity, the new system has been proven to be an improvement in resolving fine-scale structures and variability and provides more accurate information on the major physical variables, like temperature, salinity, and horizontal currents. AMM15 improvements are evident from the validation against high-resolution observations, available in some selected areas of the model domain. However, validation at the basin scale and using daily means penalized the high-resolution system and does not reflect its superior performance. This increment in resolution also improves the capabilities to provide marine information closer to the coast even if the coastal processes are not fully resolved by the model.
Highlights
The North-West European Shelf (NWS) is a shallow shelf region consisting of the North Sea, the Irish Sea, the English Channel, and the surrounding waters of the Skagerrak and Kattegat in the east and the north and south-west approaches in the west; see Fig. 1
The countries that have coastlines in the NWS are in the main densely populated in these coastal regions and so there are significant populations that are directly affected by the marine environment in the NWS, with coastal flooding a particular issue due to the high tides, waves, and storm surges
The AMM7 initial conditions are from the operational system, while for AMM15 they are from an extension of the non-assimilating experiments presented in Graham et al (2018a), which finished at the end of 2014
Summary
The North-West European Shelf (NWS) is a shallow shelf region consisting of the North Sea, the Irish Sea, the English Channel, and the surrounding waters of the Skagerrak and Kattegat in the east and the north and south-west approaches in the west; see Fig. 1. There is a significant history of marine monitoring and prediction in support of sustainable use of our marine environment, with the safety of life at sea imperative, leading to surface wave models providing forecasts, followed by ocean model forecasts predominantly by the need for storm surge prediction and (more recently) currents and hydrodynamics, mainly led by defence requirements, and supporting industry and marine planning (Siddorn et al, 2016). The NWS system has three major components: an ocean model coupled with a biogeochemistry model and a variational data assimilation scheme This system runs a forecast cycle every day to provide 6 d forecasts of the physical and biogeochemical variables in this area. Documents/PUM/CMEMS-NWS-PUM-004-013.pdf, last access: 15 August 2019); WAV_004_014
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