Mapping the underside of an iceberg with a modified underwater glider

Zhou, Mingxi; Bachmayer, Ralf; deYoung, Brad

doi:10.1002/rob.21873

Cited by 28 publications

(18 citation statements)

References 27 publications

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“…A similar approach could potentially be applied to other platforms operating under ice, where the position of the platform is unknown or uncertain. For example, gliders and underwater vehicles often use acoustics to measure water depth with recent advances including the integration of multibeam echosounders and scanning sonars for seabed and iceberg mapping (Wölfl et al, 2019; Zhou et al, 2019). Our simple depth‐based approach could provide an additional constraint on geolocation in areas of known bathymetry.…”

Section: Discussionmentioning

confidence: 99%

Bathymetry‐Constrained Navigation of Argo Floats Under Sea Ice on the Antarctic Continental Shelf

Wallace

Wijk

Rintoul

et al. 2020

Geophysical Research Letters

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Antarctic continental shelf waters are poorly sampled, particularly beneath sea ice during winter. Profiling floats could help fill this gap, but floats are unable to surface to obtain a satellite position when ice is present. We deployed Argo profiling floats in a coastal polynya with a novel mission to rest on the sea floor between profiles. “Parking” on the seabed minimized the drift of the floats and allowed year‐round, full‐depth measurements over multiple winters. Measurements of water depth derived from the floats were used in combination with known bathymetry to constrain the position of profiles collected under ice. Errors were quantified by withholding known positions and comparing them to estimated positions; the bathymetrically constrained algorithm outperformed linear interpolation. A similar approach could potentially be used to geolocate other under‐ice oceanographic platforms that measure water depth.

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Section: Discussionmentioning

confidence: 99%

Bathymetry‐Constrained Navigation of Argo Floats Under Sea Ice on the Antarctic Continental Shelf

Wallace

Wijk

Rintoul

et al. 2020

Geophysical Research Letters

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“…Finally, we applied the surface reconstruction method (Zhou et al, 2019) to the processed point cloud. Figure 11 shows multiple views of the final iceberg rendering.…”

Section: Field Experimentsmentioning

confidence: 99%

“…In Zhou et al (2016a), an adaptive heading controller was developed for a hybrid Slocum underwater glider to perform autonomous iceberg wall-following and collision avoidance. Advancements have been made to improve the iceberg wall-following capability (Zhou et al, 2016b) with field evaluation on a grounded iceberg presented in Zhou et al (2019). Similar work was done by McEwen et al (2018), where a larger AUV equipped with a side-looking multi-beam sonar and a wall-following algorithm was deployed to survey a floating iceberg.…”

Section: Introductionmentioning

confidence: 97%

Surveying a Floating Iceberg With the USV SEADRAGON

2021

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The calving, drifting, and melting of icebergs has local, regional, and global implications. Besides the impacts to local ecosystems due to changes in seawater salinity and temperature, the freshwater influx and transport can have significant regional effects related to the ocean circulation. The increased influx of freshwater ice due to increase calving from ice shelves and the destabilization of the continental ice sheet will affect sea levels globally. In addition, drifting icebergs pose threats to offshore operations because they could damage offshore installations, e.g., pipelines and subsea manifolds, and interrupt marine transportation. Iceberg drift and deterioration models have been developed to better predict climate change and protect offshore operations. Iceberg shape is one of the most critical parameters in these models, but it is challenging to obtain because of iceberg movement caused by winds, waves, and currents. In this paper, we present an algorithm for iceberg motion estimation and shape reconstruction based on in-situ point cloud measurements. The algorithm is developed based on point cloud matching strategies, policy-based optimization, and Kalman filtering. A down-sampling method is also integrated to reduce the processing time for possible real-time applications. The motion estimation algorithm is applied to a simulated data set and field measurements collected by an Unmanned Surface Vehicle (USV) on a free-floating, translating, and rotating, iceberg. In the field data, the above-water iceberg surface was measured with a scanning LIDAR, while the below-water portion (0–50 m) was profiled using a side-looking multi-beam sonar. When applying the motion estimation algorithm to these two independent point cloud measurements collected by the two sensing modalities, consistent iceberg motion estimates are obtained. The resulting motion estimates are then used to reconstruct the iceberg shape. During the field experiment, additional oceanographic measurements, such as temperature, ocean current, and wind, were collected simultaneously by the USV. We have observed water upwelling and a colder and fresher water plume at the sea surface downstream the iceberg. Combining the iceberg shape rendering and the surrounding environmental measurements, we estimated the iceberg melting parameters due to the sensible heat flux and surface wave erosion at different iceberg sections.

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“…In [171], Zhou et al report on the integration of a mechanical scanning sonar (Tritech Micron) into a Slocum Glider for the purposes of iceberg survey and mapping off the coast of Newfoundland, Canada. A detailed discussion of the iceberg search and acoustic processing algorithms is given, along with results of the in situ and postprocessed volume estimates for the target icebergs encountered during field trials.…”

Section: Underwater Glidersmentioning

confidence: 99%

Scientific Challenges and Present Capabilities in Underwater Robotic Vehicle Design and Navigation for Oceanographic Exploration Under-Ice

et al. 2020

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This paper reviews the scientific motivation and challenges, development, and use of underwater robotic vehicles designed for use in ice-covered waters, with special attention paid to the navigation systems employed for under-ice deployments. Scientific needs for routine access under fixed and moving ice by underwater robotic vehicles are reviewed in the contexts of geology and geophysics, biology, sea ice and climate, ice shelves, and seafloor mapping. The challenges of under-ice vehicle design and navigation are summarized. The paper reviews all known under-ice robotic vehicles and their associated navigation systems, categorizing them by vehicle type (tethered, untethered, hybrid, and glider) and by the type of ice they were designed for (fixed glacial or sea ice and moving sea ice).

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Mapping the underside of an iceberg with a modified underwater glider

Cited by 28 publications

References 27 publications

Bathymetry‐Constrained Navigation of Argo Floats Under Sea Ice on the Antarctic Continental Shelf

Bathymetry‐Constrained Navigation of Argo Floats Under Sea Ice on the Antarctic Continental Shelf

Surveying a Floating Iceberg With the USV SEADRAGON

Scientific Challenges and Present Capabilities in Underwater Robotic Vehicle Design and Navigation for Oceanographic Exploration Under-Ice

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