An open source, versatile, affordable waves in ice instrument for scientific measurements in the Polar Regions

Abstract

Sea ice is a major feature of the polar environments. Recent changes in the climate and extent of the sea ice, together with increased economic activity and research interest in these regions, are driving factors for new measurements of sea ice dynamics. Waves in ice are important as they participate in the coupling between the open ocean and the ice-covered regions. Measurements are challenging to perform due to remoteness and harsh environmental conditions. While progress has been made in observing wave propagation in sea ice using remote methods, these are still relatively new measurements and would benefit from more in situ data for validation. In this article, we present an open source instrument that was developed for performing such measurements. The versatile design includes an ultra-low power unit, a microcontroller-based logger, a small microcomputer for on-board data processing, and an Iridium modem for satellite communications. Virtually any sensor can be used with this design. In the present case, we use an Inertial Motion Unit to record wave motion. High quality results were obtained, which opens new possibilities for in situ measurements in the polar regions. Our instrument can be easily customized to fit many in situ measurement tasks, and we hope that our work will provide a framework for future developments of a variety of such open source instruments.Keywords Waves in ice ⋅ Open Source instrument ⋅ In situ measurements 1 Measurements of waves in iceThe interaction between surface waves and sea ice involves many complex physical phenomena such as viscous damping (Weber, 1987; Rabault and others, 2017), wave diffraction (Squire and others, 1995), and nonlinear effects in the ice (Liu and Mollo-Christensen, 1988). Therefore, it is complex and still an area of ongoing research (Rabault, 2018;Squire, 2018). Better understanding and modeling of wave propagation in sea ice can allow for the improvement of ocean models to be used for climate, weather and sea state predictions (Christensen and Broström, 2008), the estimation of ice thickness (Wadhams and Doble, 2009), and the analysis of pollution dispersion in the Arctic environment (Pfirman and others, 1995;Rigor and Colony, 1997). More generally, all these aspects must be better understood to allow safe, environment-friendly operations in the Arctic. Therefore, there is considerable interest in measuring sea ice dynamics.While the use of Synthetic Aperture Radar (SAR) images from satellites to obtain spectral wave information has made significant progress lately, they are still not standard measurements. Indeed, they require the satellite to be in a particular sampling mode (wide swath), as well as accurate prediction of the azimuth cutoff wavelength. This is vital for accurate determination of the wave energy, and is made complicated by the presence of sea ice (Ardhuin and others, 2017; Stopa and others, 2018). Therefore, in situ measurements are still a key method for measurements of waves in ice. In addition, as remote sensing and satellite-base...

Experimental evidence for a universal threshold characterizing wave-induced sea ice break-up

“…1a) on the 7th of December 2019. The instruments deployed consisted of two wave buoys, denoted as WB in the following (Spotter buoys, from Sofar Ocean Technologies), and two low-cost open-source ice motion loggers (Rabault et al, 2020, hereafter referred to as ice buoys and denoted IB). Both the wave and ice buoys are compact solar-charged position and motion recording instruments with real-time Iridium transmission capability.…”

“…For high frequency waves, the accuracy of the ice buoy is O(mm) (Rabault et al, 2016), but the Continents are shaded dark gray, whereas sea ice concentration is represented by the light gray shades using two contour levels, indicative of (a) sea ice concentration of 25% and 75% derived from AMSR2 for 02-Jan-2020 (Spreen et al, 2008), for light and dark grey respectively, and (b) open drift ice and very close drift ice obtained from the Norwegian Meteorological Institute Ice Service for 23-Mar-2020, for light and dark grey respectively. Instruments were deployed along a line perpendicular to the unbroken ice edge (see insets), and consisted of wave buoys (WB: Spotter buoys, Sofar Ocean Technologies) and open source ice motion loggers (referred to as ice buoys, IB; Rabault et al, 2020). Note that in (a), IB1 is shifted laterally for visualization purposes but in reality it is only 40 m apart from WB2.…”

“…noise level increases with decreasing wave frequencies (Rabault et al, 2020). For more technical details on the wave and ice buoys the reader is referred to Raghukumar et al (2019) and Rabault et al (2020), respectively.…”

Observing Waves in Sea Ice With ICESat‐2

“…Despite challenges in adopting and verifying this new technique, IS‐2 altimetry represents a unique opportunity to observe waves in sea ice and define the MIZ mechanistically. Coincident measurements, especially with SAR (Ardhuin et al, ; Stopa et al, ), wave buoy‐based spectral measurements of waves in ice (Marchenko et al, ; Rabault et al, ; Smith & Thomson, ), and of the FSD (Horvat et al, ), will be necessary to refine and increase confidence in this methodology, increasing the number of observations of waves in ice by orders of magnitude.…”

Wave-ice interaction in the North-West Barents Sea

“…Custom accelerometer unit manufactured in the University of Oslo were equipped with VN-100 [23]. The VN-100 is a miniature, high-performance Inertial Measurement Unit (IMU) and Attitude Heading Reference System (AHRS).…”