Turbulent heat exchange over polar leads – 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 a few meters to several kilometers for different meteorological and surface conditions. Generally, we found under same temperature differences between ice and water and same meteorological conditions for small leads a decrease of lead averaged surface heat flux with lead width (as often observed in experimental studies), but for wider leads a significant increase.

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 these in some points.