Author(s): Mikko Suominen; Henrik Aalto; Jakke Kulovesi; Mikko Lensu; Pentti Kujala; Keith Soal; Jonni Lehtiranta
Keywords: No Keywords
Abstract: Ice thickness and the severity of ice conditions are of interest when maritime transportations and offshore operations are planned in ice infested waters. Due to the interest towards ice thickness, different shipborne methods to determine the thickness have been developed. Visual observations have long traditions in collecting information on ice conditions onboard ships. However, the accuracy of the measurements has not been studied rigorously. Thus, the aim of the paper is to study the accuracy of the visual observations. The visual observations are compared with the ice thickness measurements conducted with the electromagnetic sounding and the stereo camera system. In addition, the observers are compared with each other. The measurements were conducted in the Southern Ocean onboard S. A. Agulhas II during South African National Antarctic Expedition in austral summer 2013-2014. The ice conditions mainly consisted of drifting ice floe fields and the deformation level of the floes increased towards South. The results show that the observers generally share the same opinion about ice thickness. Furthermore, the visually observed ice thickness is close to the thickness measured with the EM device. However, visual observations indicate clearly higher ice thickness than the stereo camera measurements. The difference in camera measurements is expected to results from the floes breaking into pieces before arriving to the vicinity of the cameras.