Influence of leads in sea ice on the temperature of the atmospheric boundary layer during polar night

The maximum effect of open leads within sea ice on the near‐surface atmospheric temperature is estimated using a 1D atmospheric model coupled with a thermodynamic snow/sea ice model. The study is restricted to clear‐sky conditions during polar night. The model is initialized with a typical wintertime atmospheric temperature profile. Results are analyzed at different integration times corresponding to different fetches over the fractured sea ice as a function of wind speed and sea ice concentration A . The results demonstrate that for A > 90% small changes in the sea ice fraction have a strong effect on the near‐surface temperature. A change by 1% causes a temperature signal of up to 3.5 K. A threshold value of about 4 m s −1 for the 10‐m wind speed divides the air‐ice interaction process into a weak‐wind and strong‐wind regime.