Analysis of Iceberg Drift Trajectories Using the Multivariate Empirical Mode Decomposition
- Leif Erik Andersson (Norwegian University of Science and Technology (NTNU)) | Francesco Scibilia (Statoil Research Center and NTNU) | Luke Copland (University of Ottawa) | Muhammad Faisal Aftab (NTNU) | Lars Imsland (NTNU)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
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In this study we show how to detect and extract the tidal and inertial oscillation from iceberg velocity data by using the multivariate empirical model decomposition. Due to the similar frequencies of both oscillations in regions subject to drifting icebergs, this is an extremely challenging filtering problem. The method is tested on two iceberg drift trajectories from the east coast of Canada, one at about 51°N and one at about 76.5°N. The two icebergs differ in latitudinal location, such that the inertial and tidal oscillations in the first data set have a slightly different frequency and in the other they are approximately the same. For the latter case a second filtering stage has to be included that uses tidal current information from a tidal current model. Finally we show how the multivariate empirical model decomposition can be used to analyze connections between current, wind and iceberg velocities. This information may help to improve either the ocean current and meteorological models or the iceberg drift model.
Icebergs provide a threat to marine navigation and offshore installations. A good operational iceberg drift forecast is therefore important for marine operations such as station keeping in regions subjected to drifting icebergs. A simplistic mechanistic dynamic iceberg drift model was developed in the 1980’s (Sodhi and El-Tahan, 1980) and further improved and tested by among others Mountain (1980); EI-Tahan et al. (1983); Smith (1993); Bigg et al. (1996); Eik (2009); Turnbull et al. (2015). An operational iceberg drift model was developed by the National Research Council of Canada and implemented at the Canadian Ice Service (CIS) and other agencies (Kubat et al., 2005).
However, large uncertainties in iceberg driving forces and in iceberg model parameters make the drift forecasting challenging. In fact, even the hindcasting of an iceberg drift trajectory with ocean currents, wind and waves measured in close proximity of the iceberg is difficult and not always successful (Smith, 1993; Andersson et al., 2017b).
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