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Sea ice kilometer-scale characteristics are not explicitly represented in weather and climate model systems. However, due to the large differences of the surface temperature between sea ice and ocean, sea ice-free areas (leads, polynyas, etc.) can have a strong impact on the surface heat fluxes and, in turn, on atmospheric dynamics. In the present study we analyze the atmospheric response to changes in the sea ice characteristics in the marginal ice zone of the Fram Strait and Barents Sea. A kilometer-scale convection permitting atmospheric modeling system is used. The model sensitivity experiment is idealized, since there is no complete information on sea ice on these scales available. Instead, we are merging information from the passive microwave satellite product of sea ice concentration with a sea ice lead product based on thermal infrared sensors. An important constraint is that the sea ice-free areas are introduced locally, but on scales of 100 km the sea ice coverage is kept constant for both the experiments. The sensitivity of air-sea fluxes, atmospheric temperature, and winds is analyzed between the model experiments. In general, the standard deviation of the changes in surface air temperature and winds is, on large scales, about 2 K and 2 m/s, respectively. Those values are in the same order as the mean 12-hr forecast error of advanced weather forecast models in this region.

Plain Language Summary Modern weather and climate models as well as reanalysis products tend to have deficiencies in polar regions. One of the issues is the representation of the spatial structure of sea ice and its interaction with the ocean and atmosphere. For example, there are problems in accuracy of kilometer-scale sea ice characteristics in model simulations or satellite monitoring products. Currently, in most of atmospheric modeling systems, the sea ice cover is represented as a relatively smooth field, therefore expected to have important consequences for the atmospheric dynamics. In the present study we use a high-resolution numerical weather prediction system to study the effect of presence of kilometer-scale features in sea ice concentration on the atmosphere. We introduce these by combining a coarse resolution sea ice concentration product with a dedicated fine resolution sea ice lead product. The main objective is to analyze the impact range and strength of the effect on near-surface temperature and wind. The study shows that impact is significant in areas up to 500-1,000 km away from the sea ice edge. This impact, as large as the forecast accuracy of a 12-hr forecast, implies that it will be beneficial for model applications to improve our capabilities in monitoring and simulating of sea ice lead characteristics.