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Article

Estimating the Speed of Ice-Going Ships by Integrating SAR Imagery and Ship Data from an Automatic Identification System

Finnish Meteorological Institute, PB 503, FI-00101 Helsinki, Finland
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Remote Sens. 2018, 10(7), 1132; https://doi.org/10.3390/rs10071132
Received: 31 May 2018 / Revised: 14 July 2018 / Accepted: 17 July 2018 / Published: 18 July 2018
The automatic identification system (AIS) was developed to support the safety of marine traffic. In ice-covered seas, the ship speeds extracted from AIS data vary with ice conditions that are simultaneously reflected by features in synthetic aperture radar (SAR) images. In this study, the speed variation was related to the SAR features and the results were applied to generate a chart of expected speeds from the SAR image. The study was done in the Gulf of Bothnia in March 2013 for ships with ice class IA Super that are able to navigate without icebreaker assistance. The speeds were normalized to dimensionless units ranging from 0 to 10 for each ship. As the matching between AIS and SAR was complicated by ice drift during the time gap (from hours to two days), we calculated a set of local statistical SAR features over several scales. Random forest tree regression was used to estimate the speed. The accuracy was quantified by mean squared error and by the fraction of estimates close to the actual speeds. These depended strongly on the route and the day. The error varied from 0.4 to 2.7 units2 for daily routes. Sixty-five percent of the estimates deviated by less than one speed unit and 82% by less than 1.5 speed units from the AIS speeds. The estimated daily mean speeds were close to the observations. The largest speed decreases were provided by the estimator in a dampened form or not at all. This improved when the ice chart thickness was included as a predictor. View Full-Text
Keywords: synthetic aperture radar; automatic identification system; operational ice information; ice thickness; regression synthetic aperture radar; automatic identification system; operational ice information; ice thickness; regression
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MDPI and ACS Style

Similä, M.; Lensu, M. Estimating the Speed of Ice-Going Ships by Integrating SAR Imagery and Ship Data from an Automatic Identification System. Remote Sens. 2018, 10, 1132. https://doi.org/10.3390/rs10071132

AMA Style

Similä M, Lensu M. Estimating the Speed of Ice-Going Ships by Integrating SAR Imagery and Ship Data from an Automatic Identification System. Remote Sensing. 2018; 10(7):1132. https://doi.org/10.3390/rs10071132

Chicago/Turabian Style

Similä, Markku, and Mikko Lensu. 2018. "Estimating the Speed of Ice-Going Ships by Integrating SAR Imagery and Ship Data from an Automatic Identification System" Remote Sensing 10, no. 7: 1132. https://doi.org/10.3390/rs10071132

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