Observations of the heat budget at the ocean-ice interface during an anomalous Arctic winter

The winters of 2017/18 and 2018/19 saw unprecedented sea ice minima in the Bering and Chukchi Seas. Kotzebue Sound, located in the southeastern corner of the Chukchi Sea, remained largely ice-free throughout the winter for the first time in both recorded history and indigenous oral history. The only sea ice that persisted throughout the winter was shorefast ice and most of this occupied a small corner of the sound near the outflow of the Noatak and Kobuk Rivers. We present oceanographic and atmospheric time series from a heavily instrumented sea ice station located on this shorefast ice above the river outflow channel. This station was deployed as part of the Ikaaġvik Sikukun project, in which hypotheses and subsequent observational programs were co-produced in partnership with an indigenous advisory council in Kotzebue. The measurements allow us to quantify the heat budget of the ice in this channel, and identify the ocean as the primary source of heat contributing to thinning of the ice in the outflow channel, which began in early February and accelerated rapidly before recovery of the station in April. We will use oceanographic measurements from the Bering Strait and the Mouth of Kotzebue sound in concert with the sea ice station observations to identify the transport pathways for heat in the Sound and their link to the greater Chukchi Sea region.