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This study discusses the implementation of a learning sequence with interactive computational modelling activities in the context of introductory marine geophysics university courses. The application of two computer modelling systems, Modellus and Mirone, is considered for the introduction of mathematical physics models of interest in marine geophysics to students having only basic level knowledge of physics and mathematics and no prior knowledge of scientific computation. Modellus is used to compute the theoretical depth of the seafloor predicted using the plate cooling model, while is used to manipulate and display actual bathymetric data in the region of mid-ocean ridges. The combination of both software systems is illustrative and insightful of functionalities suitable to develop other computational modelling activities for marine geophysics as well as for other areas of the geosciences. [ABSTRACT FROM AUTHOR]

Typification of ice conditions in the Arctic is an essential step to solve important applied problems in the field of arctic marine transportation since in such studies a variety of ice conditions is often described by a predefined set of typified scenarios that directly influence the results. Criteria for ice typification traditionally include the parameters that represent all the sea area, e.g., total ice coverage, area of old ice and other. However, our practical experience shows that such criteria do not always capture the real severity of ice conditions for navigation. This paper describes an idea of using the duration of ship voyage as an alternative criterion for typification of ice conditions in the Arctic. Such approach makes it possible to eliminate contradictions between regional ice characteristics and ice parameters on a given shipping line. To estimate the voyage time, it is necessary to take into account the real practice of arctic navigation, according to which ships tend to sail by optimized routes with the minimum duration of the voyage. To solve the task of ice route optimization we developed an original algorithm that is based on wave isochrone method. We calculate ship speed using an empirical formula taking into account the main particulars of ship and parameters of ice. As a case study, we typified the ice conditions in the Barents and Kara Seas from 1997 to 2017 on the route from Murmansk to Dikson. These calculations showed that the voyage time criterion gives different results in comparison with the conventional criteria. We suppose that the further study and refinement of the described approach is a promising way to typify ice conditions in the Arctic with regard to ship navigation. [ABSTRACT FROM AUTHOR]

Rip currents are one of the most dangerous coastal hazards for swimmers. In order to minimize the risk, a coastal operational-process based-model system can be utilized in order to provide forecast of nearshore waves and currents that may endanger beach goers. In this paper, an operational model for rip current prediction by utilizing nearshore bathymetry obtained from video image technique is demonstrated. For the nearshore scale model, XBeach1 is used with which tidal currents, wave induced currents (including the effect of the wave groups) can be simulated simultaneously. Up-to-date bathymetry will be obtained using video images technique, cBathy2. The system will be tested for the Egmond aan Zee beach, located in the northern part of the Dutch coastline. This paper will test the applicability of bathymetry obtained from video technique to be used as input for the numerical modelling system by comparing simulation results using surveyed bathymetry and model results using video bathymetry. Result s show that the video technique is able to produce bathymetry converging towards the ground truth observations. This bathymetry validation will be followed by an example of operational forecasting type of simulation on predicting rip currents . Rip currents flow fields simulated over measured and modeled bathymetries are compared in order to assess the performance of the proposed forecast system. [ABSTRACT FROM AUTHOR]

Low-frequency (LF) sound speed and attenuation in sandy/silty seabottoms have recently been analyzed and summarized from long-range field measurements in shallow water [Zhou, Zhang and Knobles, J. Acoust. Soc. Am., 125, 2847-2866, 2009]. Field measurements conducted at 20 locations in different coastal zones around the world were analyzed. The seabed attenuations, inverted from different acoustic field characteristics, exhibit similar magnitude and nonlinear frequency dependence below 2000 Hz. The present paper shows that both LF field-derived sound speed and attenuation in the bottom can be equally well described by the Biot-Stoll model, the Buckingham VGS model, the Chotiros-Isakson BICSQS model, and the Pierce-Carey model. Possible ranges of the physical parameters for each of these four seabed acoustic models are estimated based on the LF field-inverted sound speed and attenuation. These four models with different physical mechanisms in consideration may result in almost identical nonlinear frequency dependence of sound attenuation in sandy/silty seabottoms. [ABSTRACT FROM AUTHOR]