WAAXT used a series of field campaigns to better understand the small-scale physical processes at the heart of wave-ice feedbacks. Autonomous, shipboard, and manually-sampled instrumentation measured the effects of wind/wave events over a range of scales; capturing both small-scale physical processes and their bulk effects.
Technological advances included the development of an autonomous surface vehicle capable of measuring the horizontal structure of turbulence in the upper-ocean and the lower atmosphere, and the effects thereof on sea ice formation. These in situ measurements were supported by measurements taken from a variety of drifting buoys, unmanned aerial vehicles (UAVs) with custom payloads, as well as a crewed aircraft.
Supported by these technical developments, WAAXT was able to pursue the scientific objectives during 4 field campaigns, two in the Lower St. Lawrence Estuary (Canada), and two in the Arctic (Canada, Denmark).
One challenge in modelling wave-ice feedbacks has been in quantifying the attenuation of waves in sea ice. WAAXT research showed that physical interactions within the ice pack, rather than under-ice turbulence is often the key driver for wave attenuation. Furthermore, that the mechanism for that attenuation varies significantly with ice type and ice floe density.
During the freeze up season, waves and wave-driven turbulence inhibit the formation of an ice layer that would isolate the atmosphere from the ocean. This means that more heat is transferred from the ocean to the atmosphere, and the ocean mixed layer cools more than it would if ice was present. By directly measuring ice formation, upper-ocean turbulence, and atmospheric forcing, WAAXT was able to show that wave-driven turbulence directly affects ice formation rates and was able to develop a metric for predicting the onset of ice formation. Numerical modelling was then used to show the seasonal effects of these processes.
