Data collected for a unique Arctic experiment provides insight into ocean freeze-up process

Instrumented tower on the bow of the icebreaker R/V Sikuliaq, as the ship navigates through consolidated 'pancake ice.'  (Credit: Ola Persson, CIRES)
Instrumented tower on the bow of the icebreaker R/V Sikuliaq, as the ship navigates through consolidated 'pancake ice.' (Credit: Ola Persson, CIRES)

In 2015, researchers aboard the National Science Foundation icebreaker R/V Sikuliaq collected air, ice and ocean measurements for the ‘Sea State’ field campaign in the Beaufort and Chukchi Seas. In a new article to be published in the Journal of Geophysical Research, CIRES and NOAA researchers from the Physical Sciences Division and collaborators describe the field experiment and use the data to characterize the near-surface environment during the autumn freeze-up. Their results will help improve the understanding of air-ice-ocean interactions and provide validation of coupled air-ice-ocean models now under development.

This study was a unique opportunity to sample the ocean freeze-up process, and the large number of measurements taken will improve understanding of the interactions between the atmosphere, ice, and upper ocean. The research team’s analysis captures the transition through new, growing ice and ice-edge periods. The formation of new, thin sea ice (less than 50 cm thick) quickly produces near-surface air temperatures over the ice that are significantly colder than those over open water near the ice edge. These colder temperatures can lead to an off-ice flow of cold air that greatly enhances the heat loss from the nearby open water, strong winds near the ice edge, and enhanced ice drift. The thermal and salinity structure of the upper ocean is highly variable and appears associated with bottom topography, upper-ocean eddies, and the growing ice cover.

The ocean freeze-up process is becoming more important in the “New Arctic” because of the greater summer melt-back of sea ice and increased human activity. Coupled air-ice-ocean measurements such as these are key to understanding this increasingly important freeze-up process, have not been done to this extent previously, and are necessary for designing and evaluating air-ice-ocean coupled models currently being developed. These models include both short-term (0-10 day) weather and ice forecast models for operations (shipping, resource extraction, search-and-rescue, tourism, etc.) and longer-term models (seasonal to climate).

Authors of "Shipboard Observations of the Meteorology and Near-Surface Environment During Autumn Freeze-up in the Beaufort/Chukchi Seas" are: Ola Persson, Byron Blomquist, and Chris Fairall of the ESRL Physical Sciences Division, Peter Guest of the Naval Postgraduate School, Sharon Stammerjohn of the CU Institute for Arctic and Alpine Research, Luc Rainville and Jim Thomson of the Univ. of Washington, Björn Lund of the Univ. of Miami, and Stephen Ackley of the UTSA Snow and Ice Geophysics Laboratory.