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Analysis of ocean fronts' uncertainties indicates that they result from indiscernibility of their spatial position and fuzziness of their intensity. In view of this, a flow hierarchy for uncertainty representation of ocean fronts is proposed on the basis of fuzzy-rough set theory. Firstly, raster scanning and blurring are carried out on an ocean front, and the upper and lower approximate sets, the indiscernible relation in fuzzy-rough theories and related operators in fuzzy set theories are adopted to represent its uncertainties, then they are classified into three sets: with members one hundred percent belonging to the ocean front, belonging to the ocean front's edge and definitely not belonging to the ocean front. Finally, the approximate precision and roughness degree are utilized to evaluate the ocean front's degree of uncertainties and the precision of the representation. It has been proven that the method is not only capable of representing ocean fronts' uncertainties, but also provides a new theory and method for uncertainty representation of other oceanic phenomena.

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Waterway is a kind of narrow water area which connects mainland or islands. It acts the role of channel or passage, as the only path through some area. Usually, waterways exist with the islands nearby in the sea. So the spatial relationship between islands and waterways is very important. In this paper, spatial interaction model is used to describe the relationship and the importance of the location of islands in research area is analyzed.