Quantification of ice production in Laptev Sea polynyas and its sensitivity to thin-ice parameterizations in a regional climate model

Abstract

Abstract. The quantification of sea-ice production in the Laptev Sea polynyas is important for the Arctic sea-ice budget and the heat loss to the atmosphere. We estimated the ice production for the winter season 2007/2008 (NovemberApril) based on simulations with the regional climate model COSMO-CLM at a horizontal resolution of 5 km and compared it to remote sensing estimates. A reference and five sensitivity simulations were performed with different assumptions on grid-scale and subgrid-scale ice thickness considered within polynyas, using a tile approach for fractional sea ice. In addition, the impact of heat loss on the atmospheric boundary layer was investigated.About 29.1 km 3 of total winter ice production was estimated for the reference simulation, which varies by up to +124 % depending on the thin-ice assumptions. For the most realistic assumptions based on remote sensing of ice thickness the ice production increases by +39 %. The use of the tile approach enlarges the area and enhances the magnitude of the heat loss from polynyas up to +110 % if subgrid-scale open water is assumed and by +20 % for realistic assumptions. This enhanced heat loss causes in turn higher ice production rates and stronger impact on the atmospheric boundary layer structure over the polynyas. The study shows that ice production is highly sensitive to the thin-ice parameterizations for fractional sea-ice cover. In summary, realistic ice production estimates could be retrieved from our simulations. Neglecting subgrid-scale energy fluxes might considerably underestimate the ice production in coastal polynyas, such as in the Laptev Sea, with possible consequences on the Arctic sea-ice budget.

Retrieval of Wintertime Sea Ice Production in Arctic Polynyas Using Thermal Infrared and Passive Microwave Remote Sensing Data

“…The Laptev Sea flaw lead polynyas, regularly forming due to off‐shore components of the average wind‐patterns along the fast‐ice edge on the Siberian shelf (between approximately 70°N and 100°E, Figure ), have been subject to many studies in the past (Bauer et al, ; Bareiss & Görgen, ; Dmitrenko et al, , ; Ernsdorf et al, ; Gutjahr et al, ; Iwamoto et al, ; Martin & Cavalieri, ; Willmes et al, ;Tamura & Ohshima, , and others). Most of these listed studies were aimed toward the characterization of polynya dynamics, water mass transformations, and sea ice formation in general, as those processes are all related to the circumstance that the Laptev Sea serves as one of the major source areas for sea ice export into the Transpolar Drift system (Dethleff et al, ; Krumpen et al, ; Itkin & Krumpen, ), with potential implications for the Arctic sea ice budget in general.…”

“…For approximately 40 years, various studies showed that remote sensing approaches using passive microwave and thermal infrared data have proven to be valuable tools for this task. The resulting data can be utilized for verifying or augmenting (regional) climate and ocean models (Ebner et al, , ; Gutjahr et al, ; Sansiviero et al, , among others).…”

A New Regional Climate Model for POLAR‐CORDEX: Evaluation of a 30‐Year Hindcast with COSMO‐CLM2 Over Antarctica

“…Its operation over the AIS is mainly limited to a few simulations in numerical weather prediction mode, studying individual snowfall events (Wacker et al, ) or polynya occurrence (Ebner et al, ; Haid et al, ). Some simulations with COSMO have been executed over polar regions (Gutjahr et al, ; Zhou et al, ), but these are mainly restricted to very short periods or studies of specific atmospheric phenomena.…”

Revising Contemporary Heat Flux Estimates for the Lena River, Northern Eurasia

“…Terrestrial runoff to the Laptev Sea during summer months allows important heat accumulation in the pycnocline, that affects the thermal state of submarine permafrost (Golubeva et al 2015) and retards ice formation in autumn by 5-6 days (Kirillov 2006). Significant sea ice production in the Laptev Sea compared to total Arctic Ocean ice budget and a direct link between warm freshwater input and ice formation (Dmitrenko et al 2009;Gutjahr et al 2016) both add importance to the correct heat flux estimates.…”