Dependency of the turbulent heat exchange over polar leads on the lead width – an LES study

Leads are Chanel-like openings in the sea-ice through which heat of several 100 Watt/m² is transferred from the ocean into the atmosphere. Even though leads account only for a view percent to the total ice coverage in polar regions, they modify the polar boundary layer significantly. Therefore, leads need to be considered in numerical weather and climate models. Since, generally leads are not explicitly resolved in these models it is important to understand the overall effect of leads of different sizes onto the boundary layer for different meteorological conditions.

With numerous Large-Eddy Simulations we investigated the dependency of the lead averaged surface heat flux on the lead width in a range between 50 m and 25 000 m for different meteorological conditions. Generally, we found under same temperature differences between ice and water and same meteorological conditions an increase of the the lead averaged heat flux with increasing lead width by more then 200% for some situations. We like to give some brief explanations of the possible causes for this behavior as well as to oppose these results to other former studies in this field, which might disagree to them in some points.