Use of remote sensing for Arctic marine operations

Doctoral student Runa A. Skarbø bridges work of SFI CIRFA SFI and SAMCoT (Sustainable Arctic Marine and Coastal Technology), hosted  by Norwegian University of Science and Technology (NTNU). In her studies, Skarbø focuses on operational use of ice intelligence retrieved from remote sensing products such as synthetic aperture radar (SAR) images, marine radar and other remote sensing technologies. The ice information, i.e. ice drift velocity, iceberg detection and tracking and ice feature identification, will be combined with drift prediction, in order to assess the related risks and scenarios for marine offshore operations in the Arctic.

During 2016, Skarbø focused on finishing the course requirement part of her doctoral studies. Courses included SAR and remote sensing technology at UiT and Arctic offshore technology, both theory and field work, at UNIS. Furthermore, she did research on ice drift prediction, which resulted in a paper on modelling iceberg drift in pack ice together with Dr. Renat Yulmetov. Additionally, Skarbø participated in a six-week research cruise to the Arctic Ocean, along with SAMCoT WP5 doctoral students Hans-Martin Heyn and Jon Bjørnø. The scope of the PhD candidates’ work during the research cruise was to collect valuable full-scale data from the Arctic and to gain experience from ships travelling in sea ice and icebreaking. The three PhD candidates plan to cooperate on joint research based on the data collected on this cruise.

Modelling iceberg drift in pack ice

Precise short-term modelling of iceberg drift is of high importance when operating in iceberg prone waters, in order to assess risk of and potential damages in a collision. However, most operational drift models consider forecasting in open water. Modelling iceberg drift in pack ice is challenging, mainly due to limited knowledge of additional resistance associated with the surrounding ice.

An iceberg drift model was developed and tested using drift hindcasting with historical metocean data from the area and measured drift of two icebergs and ice floes. The icebergs and ice floes were GPS tracked off the east coast of Greenland in 2013. The icebergs were of vastly different size, the larger one having a mass of over 16 times more than the smaller one.

The model demonstrated an acceptable level of accuracy for short-term forecasting in the region, where knowledge about winds and ocean current profiles is insufficient. Furthermore, in comparing the performance with and without including forcing from sea ice, the results showed a significant effect of sea ice forcing on the smaller iceberg but only a small difference for the larger one.

The results of the study were published in a conference paper was presented at the IAHR ICE 2016 conference in Michigan, Illinois, USA.

Figure 1 Drift trajectories of observed and modelled icebergs and ice floes. a) illustrates the larger iceberg, while b) illustrates the smaller one. Markers indicate every 24 hours. Simulations both including and excluding forcing from sea ice on the iceberg are shown.
Figure 1 Drift trajectories of observed and modelled icebergs and ice floes. a) illustrates the larger iceberg, while b) illustrates the smaller one. Markers indicate every 24 hours. Simulations both including and excluding forcing from sea ice on the iceberg are shown.

Full-scale data collection – Arctic Ocean 2016

When the opportunity arose to join the Swedish-Canadian research cruise Arctic Ocean 2016, Skarbø had no doubt that she would like to join. First, the cruise would provide valuable full-scale data from the remote Arctic, and second, the six-week cruise would provide insight and experience from the Arctic, and in sea ice and operation of icebreakers.

Skarbø works on technology to detect movement in the ice field. Her co-supervisor, Dr. Øivind Kjerstad (NTNU/UNIS), has developed an algorithm for detecting and tracking the ice drift around the vessel using the marine radar. In her PhD work, Skarbø seeks to utilize Kjerstad’s algorithm, combining the information retrieved from it with information from other sensors such as satellite SAR and/or cameras to get a complete overview of the ice drift conditions. During the Arctic Ocean 2016 research cruise, Skarbø collected data series of radar images while the ship was stationary. In addition, SAR products from Radarsat-2 along with ground truth from buoy drifters, meteorological data and rheological data from the ice was collected.

Figure 2 Skarbø checking the display cable connection between the radar operator station and her equipment, during the Arctic Ocean 2016 research cruise.
Figure 2 Skarbø checking the display cable connection between the radar operator station and her equipment, during the Arctic Ocean 2016 research cruise.

Skarbø joined the Arctic Ocean 2016 research cruise along with two other SAMCoT participants, doctoral students Hans-Martin Heyn and Jon Bjørnø. Heyn measured ice-induced accelerations on the icebreaker’s hull. Additionally, the whole cruise was documented using 180-degree front-looking and 360-degree camera systems. Thus, Skarbø and Heyn will work on comparing different sensors for use in ice action prediction on the background of the data collected from the research cruise.

Figure 4 SAMCoT researchers Bjørnø, Skarbø and Heyn at the North Pole, 21 August 2016
Figure 4 SAMCoT researchers Bjørnø, Skarbø and Heyn at the North Pole, 21 August 2016

Text and images: Runa Skarbø, CIRFA/NTNU