Theoretical heights of buoyant convection above open leads in the winter Arctic pack ice cover

A fetch‐dependent boundary‐layer model, driven by observed temperature sounding data, is used to examine theoretical heights of buoyant convection ( H ) above open leads in the wintertime pack ice of the central Arctic. Assuming wet adiabatic ascent with no entrainment or friction, H is estimated as the height at which the model‐predicted equivalent potential temperature at saturation above a lead (θ el ) intersects with the same value of equivalent potential temperature at saturation (θ e ) derived from vertical sounding profiles. H increases with increasing lead width. For a 1000‐m lead, the widest which can be reasonably expected for the central Arctic, the median value of H is approximately 1000 m, slightly below the median top of the low‐level Arctic temperature inversion layer. While H shows large variability, events of convection up to 4 km, as recently observed from lidar backscatter data, appear to be fairly rare. First, these events require an open lead of at least 10,000 m. Second, while H tends to be largest under conditions of low surface wind speed, low surface temperature, and a weak low‐level temperature inversion, this combination appears to be atypical of Arctic conditions. Third, while the meteorological conditions that should favor the development of open leads tend to minimize H , conditions favoring large H are also those in which any newly developed leads will quickly ice over.