Arctic Air-Sea Energy Fluxes during Rapid Sea-Ice Reduction

Vast Arctic areas that were usually covered by sea ice are now exposed to the atmosphere because of unseasonally early ice retreat and late arrival. Assessment of consequential changes in the energy cycle of the Arctic and their potential feedback to the variability of Arctic sea ice and marine ecosystems critically depends on the accuracy of surface flux estimates. Surface measurements of the ocean and atmosphere in the Arctic have been made from Saildrones for the past several years. These in situ measurements provide rare opportunities of estimating air-sea energy fluxes during a period of rapid reduction in Arctic sea ice. In this study, we estimate Arctic air-sea energy fluxes using the in situ measurements of Saildrones in different scenarios of sea ice: open water after ice melting, free-floating ice bands, and marginal ice zones. We compare air-sea fluxes based on the Saildrone observations to gridded flux products based on satellite data and numerical models. We demonstrate the circumstances under which they agree and differ, and we identify main sources of their discrepancies. Our results provide quantitative information of uncertainty margins in the gridded flux products, research efforts needed to improve their accuracy, and changes in the surface energy fluxes due to rapid sea ice reduction.