A case study of strong winds at an Arctic front

Abstract

Shallow arctic fronts frequently form at the edge of the arctic sea–ice by differential heatingand cooling between sea and ice surfaces. The cooling is due to a net radiative loss over theice, while the heating is mainly sensible as cold air flows from the ice to the warmer sea. Northof the surface fronts, there is normally a low-level jet with maximum easterly winds at the topof the boundary layer. It is shown from numerical simulations of a real case, that the low-leveljet can reach hurricane force when interacting with easterly winds connected to extratropicalcyclones. Strong wind is found both at an arctic front over the sea some distance from the iceedge, and at a secondary front at the ice edge. When the flow is from the ice to the sea, thesensible heating of the boundary layer is almost in balance with the cold-air advection. Theconvergence of the sensible heat flux amounts to a heating rate of more than 10 Kelvin perhour. The fronts are maintained by cross-frontal vertical circulations.