Comparison of variables from ocean, sea ice and atmosphere models as forcing data for iceberg drift and deterioration models in the Barents Sea in 2010–2014 and 2020–2021 (Part I)

Abstract. Numerical models of ocean, sea ice and atmosphere supply a wide range of information in the Arctic that are difficult to observe otherwise. Model disagreements emphasise the need to evaluate the suitability of the models for individual applications. This study compares selected ocean, sea ice and atmosphere variables from the models Topaz4b, Barents-2.5, ERA5 and CARRA in the Barents Sea during the years 2010–2014 and 2020–2021. The same data is used in the sequel paper (Herrmannsdörfer et al., 2024) to force simulations of iceberg drift and deterioration and to examine the impact of varied forcing on the iceberg simulations. Comparing Topaz4b and Barents-2.5, it is evident that sea ice is more extensive (larger sea ice concentration, thickness and southward extent) and sea surface temperatures are lower in Barents-2.5 with clear differences in the seasonal and spatial characteristics. Further, sea surface and sea ice drift speeds are larger in Barents-2.5, especially in shallow waters and the sea ice edge. On the side of atmospheric models, CARRA exhibits slightly larger 10 m wind speeds over open water while ERA5 show larger wind speeds over icy water. Those similarities and differences could partly be traced back to similarities and differences in spatial and temporal resolution, model setup, assimilated data and relations between the models. Despite fundamental difference in data assimilation, Barents-2.5 hindcast and forecast showed high similarity for some variables. The large occurrence of sea ice and its deviating representation in the models indicate large relevance for the iceberg pathways in the Barents Sea.