Changes in ocean-atmosphere heat and momentum fluxes during sea ice melt and breakup

Scott Brown1, Christopher J Zappa1, Nathan Laxague1, Carson Witte1, Andrew R Mahoney2, Sarah Renee Betcher3, Donna Hauser4, Ajit Subramaniam1, Alex Whiting5, John Goodwin6, Cyrus Harris7, Bobby Schaeffer7 and Ross Schaeffer7, (1)Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY, United States, (2)University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK, United States, (3)Farthest North Films, Juneau, AK, United States, (4)International Arctic Research Center, Fairbanks, AK, United States, (5)Native Village of Kotzebue, Kotzebue, AK, United States, (6)Community of Kotzebue, Kotzbue, AK, United States, (7)Community of Kotzebue, Kotzebue, AK, United States
In polar regions, sea ice is a crucial mediator of the interaction between earth's atmosphere and oceans. Its formation and breakup is intimately connected with local weather patterns and larger-scale climatic processes. Sea ice undergoes rapid change during Spring melt and breakup, during which areas transition from ice-covered to ice-free in a matter of weeks. This has a profound impact on the use of these regions by local indigenous populations, where activities such as hunting and fishing are central to community livelihood. In order to investigate the physical phenomena at the heart of this problem, a set of targeted, intensive observations were made over the course of two Spring melt and breakup periods in Kotzebue Sound, Alaska. These were performed using high-endurance, fixed-wing unmanned aerial vehicles (UAVs) containing custom-built scientific payloads. We present on the results of these measurements, describing the variation of sea ice radiometric properties and the flux of momentum and heat between the sea ice surface and the marine-atmospheric boundary layer (MABL) during breakup. Repeated flights over the measurement period captured the full transition in sea ice from a white, snow-covered state to a broken up, ponded state. Contributions to the total heat flux---including longwave/shortwave radiation and latent/sensible heat fluxes---are discussed. This program is part of the Ikaań°vik Sikukun project, a collaborative effort in which a local indigenous advisory council from Kotzebue and scientists from outside it participated in co-production of hypotheses and observational research.