Observing Wind-Forced Flexural-Gravity Waves in the Beaufort Sea and Their Relationship to Sea Ice Mechanics

Abstract

We developed and deployed two inertial measurement units on mobile pack ice during a U.S. Navy drifting ice campaign in the Beaufort Sea. The ice camp was more than 1000 km from the nearest open water. The sensors were stationed on thick (>1 m) first- and multi–year ice to record 3-D accelerations at 10 Hz for one week during March 2020. During this time, gale-force winds exceeded 21 m per second for several hours during two separate wind events and reached a maximum of 25 m per second. Our observations show similar sets of wave bands were excited during both wind events. One band was centered on a period of ~14 s. Another band arrived several hours later and was centered on ~3.5-s. We find that the observed wave bands match a model dispersion curve for flexural gravity waves in ~1.2-m ice with a Young’s modulus of 3.5 GPa under compressive stresses of ~0.3 MPa. We further evaluate the bending stress and load cycles of the individual wave bands and their potential role in break-up of sea ice. This work demonstrates how observations of waves in sea ice using these and similar sensors can potentially be a valuable field-based tool for evaluating ice mechanics. In particular, this approach can be used to observe and describe the combined mechanical behavior of consolidated floes relevant for understanding sea ice mechanical processes and model development.

OpenMetBuoy-v2021: An Easy-to-Build, Affordable, Customizable, Open-Source Instrument for Oceanographic Measurements of Drift and Waves in Sea Ice and the Open Ocean

“…Our inability to accurately capture climatological changes of sea ice in the polar seas has created renewed interest in the dynamic interaction between sea ice and waves. This has resulted in the last few years in a number of studies that investigate the coupling between sea ice and the ocean through theoretical considerations [1][2][3][4][5][6][7], laboratory experiments [8][9][10][11][12], and field experiments [13][14][15][16][17][18][19][20][21][22][23][24]. Despite the advances that these studies bring, there is a growing consensus that further progress in the field can only be achieved through the collection of more observations of waves in ice.…”

“…A number of groups have developed satellite-connected autonomous instruments that have been described in research articles, but that remained closed source. A few instruments we know about were released in 2006 (3) [47,50], 2016 (4) [40], and 2021 (5) [24]. By contrast, our group has decided to release our designs as open source, so that they can be freely used and improved by other groups, starting in 2018 (6) [51] and now with the present design (7).…”

Landfast Ice and Coastal Wave Exposure in Northern Alaska

“…Observations from all three sites include a few winter wave events. These are beyond the scope of this paper, though such events may be important to sea ice breakup and sea ice dynamics in general (Ardhuin et al., 2020; Johnson et al., 2021; Stopa et al., 2018). Examination of the wave spectra (not shown) from these brief events suggests that a local wind‐sea develops within an open lead near the coast.…”

A dataset of direct observations of sea ice drift and waves in ice

“…Both IWRs recorded two events of propagating flexural-gravity waves presumably forced by strong winds during passing storms. More can information be found in 67 .…”

“…The shortest observational interval was 2 weeks and the longest one and a half month (it was collected on 2021-04-22). More information is available in 67 .…”