Abstract
Abstract. Four calving events of Petermann Glacier happened in 2008, 2010, 2011, and 2012, which resulted in the drift and deterioration of numerous ice islands, some reaching as far as offshore Newfoundland. The presence of these ice islands in the eastern Canadian Arctic increases the risk of interaction with offshore operations and shipping activities. This study uses the recently developed Canadian Ice Island Drift, Deterioration and Detection database to investigate the fracture events that these ice islands experienced, and it presents a probabilistic model for the conditional occurrence of such events by analyzing the atmospheric and oceanic conditions that drive the causes behind the ice island fracture events. Variables representing the atmospheric and oceanic conditions that the ice islands were subjected to are extracted from reanalysis datasets and then interpolated to evaluate their distributions for both fracture and non-fracture events. The probability of fracture event occurrence for different combinations of input variable conditions is quantified using Bayes' theorem. Out of the seven variables analyzed in this study, water temperature and ocean current speed are identified as the most and least important contributors, respectively, to the fracture events of the Petermann ice islands. It is also revealed that the ice island fracture probability increases to 75 % as the ice islands encounter extreme (very high) atmospheric and oceanic conditions. A validation scheme is presented using the cross-validation approach and Pareto principle, and an average error of 13 %–39 % is reported in the fracture probability estimations. The presented probabilistic model has a predictive capability for future fracture events of ice islands and could be of particular interest to offshore and marine ice and risk management in the eastern Canadian Arctic. Future research, however, is necessary for model training and testing to further validate this ice island fracture model.
Highlights
With the advancement of offshore operations and shipping activities into the harsh environment in the eastern Canadian waters, these activities are being subjected to greater risks from glacial ice features (Saper, 2011)
The recurrent deterioration of the ice islands originating from four recent calving events of Petermann Glacier were studied using the data in the CI2D3 database to probabilistically investigate the conditions that lead to fracture event occurrence of the ice islands
The model validation was performed using the k-fold crossvalidation approach based on the Pareto principle, and it was found that the error between the estimated fracture probabilities from training and test sets ranged from 13 % when only the water temperature criterion is considered to 39 % for the full set of criteria
Summary
With the advancement of offshore operations and shipping activities into the harsh environment in the eastern Canadian waters, these activities are being subjected to greater risks from glacial ice features (Saper, 2011). The shipping and resource extraction industries in this region, require a better understanding of the dynamics and physical properties of these ice features to be able to devise appropriate ice management strategies for safe operations. A better understanding of the drift and deterioration characteristics of icebergs and ice islands (large tabular icebergs) is needed for risk management strategies. Ice island research studies have been mainly focused on their potential risks to shipping activities and offshore operations (Peterson, 2011; Mueller et al, 2013; Fuglem and Jordaan, 2017), as well as their meltwater input as they deteriorate and melt over large regions (Stern et al, 2015; Merino et al, 2016; Wagner et al, 2017; Crawford et al, 2018d).
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