TY - JOUR

T1 - Turbulent Heat Exchange Over Polar Leads Revisited

T2 - A Large Eddy Simulation Study

AU - Gryschka, M.

AU - Gryanik, V. M.

AU - Lüpkes, C.

AU - Mostafa, Z.

AU - Sühring, M.

AU - Witha, B.

AU - Raasch, S.

N1 - Funding Information: The authors gratefully acknowledge the computing time provided by the Resource Allocation Board on the supercomputers Lise and Emmy at NHR@ZIB and NHR@Göttingen as part of the NHR infrastructure. The calculations for this research were conducted using computing resources under project NIK00062. This study was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Grant GR 4911/1‐1 and the Federal Ministry of Education and Research (BMBF) under Grant 03F0887B in the framework of the MOSAiC project “Modeling the impact of sea‐ ice leads on the atmospheric boundary layer during MOSAiC (MISLAM).” Open Access funding enabled and organized by Projekt DEAL.

PY - 2023/6/22

Y1 - 2023/6/22

N2 - Sea ice leads play an important role in energy exchange between the ocean and atmosphere in polar regions, and therefore must be considered in weather and climate models. As sea ice leads are not explicitly resolved in such models, lead-averaged surface heat flux is of considerable interest for the parameterization of energy exchange. Measurements and numerical studies have established that the lead-averaged surface heat flux depends not only on meteorological parameters, but also on lead width. Nonetheless, few studies to date have investigated the dependency of surface heat flux on lead width. Most findings on that dependency are based on observations with lead widths smaller than a few hundred meters, but leads can have widths from a few meters to several kilometers. In this parameter study, we present the results of three series of large-eddy simulations of turbulent exchange processes above leads. We varied the lead width and air temperature, as well as the roughness length. As this study focused on conditions without background wind, ice-breeze circulation occurred, and was the main driver of the adjustment of surface heat flux. A previous large-eddy simulation study with uncommonly large roughness length found that lead-averaged surface heat flux exhibited a distinct maximum at lead widths of about 3 km, while our results show the largest heat fluxes for the smallest leads simulated (lead width of 50 m). At more realistic roughness lengths, we observed monotonously increasing heat fluxes with increasing lead width. Further, new scaling laws for the ice-breeze circulation are proposed.

AB - Sea ice leads play an important role in energy exchange between the ocean and atmosphere in polar regions, and therefore must be considered in weather and climate models. As sea ice leads are not explicitly resolved in such models, lead-averaged surface heat flux is of considerable interest for the parameterization of energy exchange. Measurements and numerical studies have established that the lead-averaged surface heat flux depends not only on meteorological parameters, but also on lead width. Nonetheless, few studies to date have investigated the dependency of surface heat flux on lead width. Most findings on that dependency are based on observations with lead widths smaller than a few hundred meters, but leads can have widths from a few meters to several kilometers. In this parameter study, we present the results of three series of large-eddy simulations of turbulent exchange processes above leads. We varied the lead width and air temperature, as well as the roughness length. As this study focused on conditions without background wind, ice-breeze circulation occurred, and was the main driver of the adjustment of surface heat flux. A previous large-eddy simulation study with uncommonly large roughness length found that lead-averaged surface heat flux exhibited a distinct maximum at lead widths of about 3 km, while our results show the largest heat fluxes for the smallest leads simulated (lead width of 50 m). At more realistic roughness lengths, we observed monotonously increasing heat fluxes with increasing lead width. Further, new scaling laws for the ice-breeze circulation are proposed.

KW - heat flux

KW - large eddy simulation

KW - polar boundary layer

KW - scaling laws

KW - sea-ice leads

UR - http://www.scopus.com/inward/record.url?scp=85163639112&partnerID=8YFLogxK

U2 - 10.1029/2022JD038236

DO - 10.1029/2022JD038236

M3 - Article

AN - SCOPUS:85163639112

VL - 128

JO - Journal of Geophysical Research: Atmospheres

JF - Journal of Geophysical Research: Atmospheres

SN - 2169-897X

IS - 12

M1 - e2022JD038236

ER -