Abstract
The parameterization of ocean/sea-ice/atmosphere interaction processes is a challenge for regional climate models (RCMs) of the Arctic, particularly for wintertime conditions, when small fractions of thin ice or open water cause strong modifications of the boundary layer. Thus, the treatment of sea ice and sub-grid flux parameterizations in RCMs is of crucial importance. However, verification data sets over sea ice for wintertime conditions are rare. In the present paper, data of the ship-based experiment Transarktika 2019 during the end of the Arctic winter for thick one-year ice conditions are presented. The data are used for the verification of the regional climate model COSMO-CLM (CCLM). In addition, Moderate Resolution Imaging Spectroradiometer (MODIS) data are used for the comparison of ice surface temperature (IST) simulations of the CCLM sea ice model. CCLM is used in a forecast mode (nested in ERA5) for the Norwegian and Barents Seas with 5 km resolution and is run with different configurations of the sea ice model and sub-grid flux parameterizations. The use of a new set of parameterizations yields improved results for the comparisons with in-situ data. Comparisons with MODIS IST allow for a verification over large areas and show also a good performance of CCLM. The comparison with twice-daily radiosonde ascents during Transarktika 2019, hourly microwave water vapor measurements of first 5 km in the atmosphere and hourly temperature profiler data show a very good representation of the temperature, humidity and wind structure of the whole troposphere for CCLM.
Highlights
The impact of the recent global climate change is most pronounced in the Arctic, where the near-surface warming effects are 2–3 times the global average [1]
CCLM was adapted to polar regions by implementing a two-layer sea ice model [34], a tile approach for sea ice [13], and modifications for the stable boundary layer [27,28]
In the monthly average, a cyclone with the center in the eastern7Kara of 20Sea is found for the mean sea-level pressure (MSLP) as well as at 500 hPa, which is consistent with the general northerly wind directions
Summary
The impact of the recent global climate change is most pronounced in the Arctic, where the near-surface warming effects are 2–3 times the global average [1]. In order to include effects of topographic winds [6], experiments for the inner Arctic representing wintertime conditions with thick ice are rare. Sea ice is considered as a mean concentration over a model realistically represented [11].are. A meteorological tower was installed on level sea ice at a distance tance of about 350 m from the ship, and atmospheric remote sensing measurements as of about. Franz Josef Land at the end of April (Figure 1), the ship remained in thick ice all the time.
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