Aircraft-based observations of turbulence fluxes over the Arctic marginal ice zone

Observations of turbulent momentum and heat fluxes over the Arctic marginal ice zone will be presented. The observations were made via three aircraft-based field campaigns - in March and April 2013 with two aircraft, and in July 2013 with one - in the vicinity of Svalbard. The campaigns were part of the ACCACIA project: Aerosol-Cloud Coupling And Climate Interactions in the Arctic. Low-level aircraft legs have been used to estimate turbulent quantities, in particular the turbulent fluxes, roughness lengths and exchange coefficients. These are analysed as a function of sea-ice concentration and sea-ice morphology. Atmospheric boundary-layer profiles will also be used to characterise boundary-layer development. Typically flights range from moderately stable conditions (occasionally in cloud) to moderately unstable conditions across the MIZ. In some cases a well-developed internal boundary layer was in place. The sea-ice roughness lengths and exchange coefficients will be compared to recently published bulk flux algorithms appropriate for summer and marginal sea ice conditions.