Two‐dimensional numerical simulations of Arctic leads: Plume penetration height

During the Arctic winter, leads can be a significant source of heat and water vapor for the atmosphere due to the extreme temperature differences between the sea surface and the atmosphere. Because of their relatively small scales, however, these openings in the pack ice cannot be explicitly resolved by large‐scale models. In the present study, a two‐dimensional cloud‐resolving model is employed to examine the development of the convective plumes that can form in the vicinity of leads. Two important considerations with respect to leads are the enhanced surface fluxes over the warm water surface and the height to which the resulting plumes penetrate, which represents the depth of the atmosphere that is directly affected by these enhanced fluxes. The dependence of plume height on ambient wind speed, orientation, and lead width is investigated. Comparisons to earlier large‐eddy simulation results generally show good agreement, while comparisons with simple analytical expressions for plume height show good agreement for cases with no cross‐lead large‐scale flow and poor agreement for cases with significant cross‐lead winds. Sensitivity experiments are run to gauge the impacts of interactive microphysical and radiative processes. When these processes are included in the simulations, plume depths increase up to 20% over the baseline case, which is in general agreement with earlier one‐dimensional results. Finally, it was found that by generalizing the surface buoyancy flux to include latent and radiative fluxes, the analytical expression for plume height could be successfully applied to the case where there is no large‐scale cross‐lead wind.