Scottish Shelf Model - Wider Loch Linnhe System

The Wider Loch Linnhe System (WLLS) model is an implementation of the Finite Volume Community Ocean Model (FVCOM) and has a domain covering many of Inner Hebrides from the southern tip of the Mull of Kintyre to the Isle of Skye in the north. The model is part of the Scottish Shelf Model (SSM) suite of hydrodynamic models and can be forced independently or nested within the wider SSM. The western boundary extends to approximately 7.5° W from Northern Ireland to the southern Outer Hebrides. The model grid is unstructured with the highest horizontal resolution in Loch Linnhe, Loch Leven and Loch Sunart, where the node spacing goes down to 15 m. The typical node spacing of these sea lochs is around 50 – 100 m, with  Lower Loch Linnhe having a typical node spacing of 100 – 150 m. Beyond Loch Linnhe, its side lochs, and Loch Sunart, the unstructured grid resolution reduces further, with the node spacing at the western boundary being around 5 km. The water column is resolved using a hybrid sigma layer scheme with 10 standard terrain following sigma layers, each representing 10 % of the water column, in water depths greater than 13 m. In areas shallower than 13 m, the water column is resolved with 2 fixed layers at the surface, each 1 m thick, 2 fixed layers at the bottom, each 2.5 m thick, and 6 sigma layers of equal spacing for the mid depths. This enables the freshwater output from Upper Loch Linnhe to be well resolved.