Atmospheric forcing of coastal polynyas in the south-western Weddell Sea

Abstract

The development of coastal polynyas, areas of enhanced heat flux and sea ice production strongly depend on atmospheric conditions. In Antarctica, measurements are scarce and models are essential for the investigation of polynyas. A robust quantification of polynya exchange processes in simulations relies on a realistic representation of atmospheric conditions in the forcing dataset. The sensitivity of simulated coastal polynyas in the south-western Weddell Sea to the atmospheric forcing is investigated with the Finite-Element Sea ice-Ocean Model (FESOM) using daily NCEP/NCAR reanalysis data (NCEP), 6 hourly Global Model Europe (GME) data and two different hourly datasets from the high-resolution Consortium for Small-Scale Modelling (COSMO) model. Results are compared for April to August in 2007–09. The two coarse-scale datasets often produce the extremes of the data range, while the finer-scale forcings yield results closer to the median. The GME experiment features the strongest winds and, therefore, the greatest polynya activity, especially over the eastern continental shelf. This results in higher volume and export of High Salinity Shelf Water than in the NCEP and COSMO runs. The largest discrepancies between simulations occur for 2008, probably due to differing representations of the ENSO pattern at high southern latitudes. The results suggest that the large-scale wind field is of primary importance for polynya development.

Circumpolar polynya regions and ice production in the Arctic: results from MODIS thermal infrared imagery from 2002/2003 to 2014/2015 with a regional focus on the Laptev Sea

“…Between 20 and 50 cm, the uncertainty increases considerably. Therefore, we constrain our analysis accordingly as a thickness range of TIT ≤ 0.2 m is widely regarded as a threshold for polynya areas and for estimates of thermodynamic ice production in polynyas (Yu and Rothrock, 1996;Adams et al, 2013;Haid et al, 2015).…”

Meteorology and oceanography of the Atlantic sector of the Southern Ocean—a review of German achievements from the last decade

“…Haid et al (2015) found a large sensitivity of coastal polynya formation in the southwestern Weddell Sea to the atmospheric forcing for the sea ice-ocean model FESOM, using different coarse resolution global atmospheric analyses/reanalysis data and high-resolution COSMO model data. Major differences occur in mountainous areas where wind is strongly guided by surface topography.…”

“…In addition, a sea-ice/ocean model with enhanced horizontal resolution (3 km) was forced with the high-resolution data of the atmospheric model (Haid et al 2015). The mean wind field for the winter 2008 is presented in Fig.…”

The Finite-volumE Sea ice–Ocean Model (FESOM2)

“…The Finite-Element Sea ice-Ocean circulation Model (FE-SOM, Wang et al, 2014) is the first mature global multiresolution model designed to simulate the large-scale ocean. A number of FESOM-based studies related to the impact of local dynamics on the global ocean (see, e.g., Hellmer et al, 2012;Haid and Timmermann, 2013;Wekerle et al, 2013;Haid et al, 2015;Wang et al, 2016a;Sein et al, 2016;Wekerle et al, 2016) indicate that the multi-resolution approach advocated by FESOM is successful and allows one to explore the impact of local processes on the global ocean with moderate computational effort (see Sein et al, 2016). Other new global multi-resolution models are appearing (see Ringler et al, 2013), and new knowledge on unstructured-mesh modeling has accumulated (for a review, see Danilov, 2013).…”