Circumpolar ROMS climatology

Brief description

Model output from a circumpolar realisation of the Regional Ocean Modelling System (ROMS). Model was run at a horizontal resolution of 1/4 degree and 31 vertical levels. Spatial domain was circumpolar out to 30 degrees South. Forcing comes from prescribed salt and heat fluxes based on a derived climatology from Tamura et al (2008). For open water regions the Tamura data is blended with open-water heat, salt and surface stress fluxes from a monthly NCEP2 climatology.

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Maintenance and Update Frequency: notPlanned

Statement: The ocean model used is ROMS, a primitive equation, finite difference model with a terrain following vertical coordinate system [HAIDVOGEL et al., 2008; Shchepetkin and McWilliams, 2009]. The model is configured with an offset pole and a circumpolar domain extending to 30◦S (Figure 1a). The horizontal resolution of the model is 1⁄4◦ and there are 31 vertical layers with smaller spacing near the surface and the bottom. The model topography comes from the 1-minute Refined Topography (RTopo-1) dataset includes elevation of the bedrock and the base of several ice shelves [Timmermann et al., 2010]. The domain encompasses the Antarctic Circumpolar Current (ACC), including its major fronts, and extends north to include the entire Kerguelen Plateau and downstream eddy field.
The model set-up, including the choice of mixing and advection schemes, mostly follows that of Galton-Fenzi et al. [2012]. The initial conditions of the seawater are a climatological mean value of the ECCO2 [Menemenlis et al., 2008; Wunsch et al., 2009] re-analysis interpolated on to the ROMS grid. To assist with initial model stability, the sea water is stationary at time t=0. The baroclinic time-step for the model is 300s and 10s for the barotropic time-step.
Polynyas have been shown to be important locations for increased primary production due to the presence of open water year round [Arrigo and van Dijken, 2003]. This in turn leads to increased populations of secondary producers such as zooplankton and krill and increased targeting of these regions by higher predators [Raymond et al., 2014]. Furthermore, brine rejection during the formation of sea ice in polynyas is considered important in the creation of dense water that sinks and is considered important in benthic-pelagic coupling, leading to an enhanced benthic community [?]. In order to capture these processes, the correct location of polynyas is essential and so for the sea ice region the open ocean boundary conditions are prescribed surface heat and salt fluxes based on sea ice concentrations from a climatology-derived model using Special Sensor Microwave Imager (SSM/I) observations [Tamura et al., 2008]. For open water regions, and during summer the Tamura et al. [2008] data are blended with open-water heat, salt and surface stress fluxes from the monthly NCEP2 climatology [?].