Interactions Between the Atmospheric Boundary Layer and the Advancing Autumn Sea Ice

Atmospheric and surface measurements during recent Arctic field programs have provided new and unique data on air-ocean and air-ice interactions during the autumn freeze-up. Sounding, remote sensing, turbulent flux, and radiative flux data from the 2014 SWERUS-C3 cruise on the R/V Oden, the 2014 cruise on the R/V Mirai, and the 2015 Sea State cruise on the R/V Sikuliaq provide direct measurements of atmospheric boundary-layer structure, cloud conditions, and surface energy fluxes, while visual images, radiometric measurements, in-situ sampling, and satellite remote sensing provide detailed information on the associated ice conditions.  This presentation will use these observations from September to early November to quantify how the atmospheric structure and surface fluxes force the initial autumn heat loss over open Arctic waters, eventually leading to ice formation and a feedback on the surface fluxes and the atmospheric boundary-layer structure.  Because of ice formation, heat loss over the new first-year ice (FYI) is diminished, though still significant until the ice thickens further and/or snow accumulation helps to insulate the heat transfer from the ice bottom.  Several boundary-layer and mesoscale processes, such as energy-balance variability, synoptic variability, off-ice airflow, and possibly low-level jets, modulate the heat loss over both the FYI and the adjacent open water, and provide significant spatial and temporal variability.