The mechanism of the formation of multiple quasi-zonal jets as well as their meridional scaling is investigated for a range of control parameters including the radius of deformation and the parameter which characterizes the polar β-plane. Flows in a rotating cylindrical domain where the depth of the fluid layer varies quadratically with distance from the center are studied using numerical simulations and laboratory experiments. The flows are generated by a spatially localized heater. The westward radiation of barotropic Rossby waves is shown to be a major factor contributing to the formation of jets such that their meridional scaling is in good agreement with a modified Rhines scaling.

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We present worst-case assessments of contamination in sea ice and surface waters resulting from hypothetical well blowout oil spills at ten sites in the Arctic Ocean basin. Spill extents are estimated by considering Eulerian passive tracers in the surface ocean of the MITgcm (a hydrostatic, coupled ice-ocean model). Oil in sea ice, and contamination resulting from melting of oiled ice, is tracked using an offline Lagrangian scheme. Spills are initialized on November 1st 1980-2010 and tracked for one year. An average spill was transported 1100km and potentially affected 1.1 million km. The direction and magnitude of simulated oil trajectories are consistent with known large-scale current and sea ice circulation patterns, and trajectories frequently cross international boundaries. The simulated trajectories of oil in sea ice match observed ice drift trajectories well. During the winter oil transport by drifting sea ice is more significant than transport with surface currents.

Numerical simulation of flows of a heavy nonviscous fluid with a free surface in the gravity field over a bed surface with an arbitrary profile Abstract -A numerical method is proposed in this paper for studying hydrodynamic flows of heavy nonviscous fluid with a free surface over an arbitrary bed profile. This arbitrary bed profile is approximated by a piecewise-linear function splitting it into a finite number of domains with a step boundary. In order to implement this method, a quasi-two-layer model of fluid flow over a step boundary is used taking into account physical processes near the step. In this paper we implement numerical modelling of various physical phenomena, such as fluid flow over a sloping bed surface, shock wave creeping on a sloping bank, a fluid column fall over a bed surface given in various ways, fluid flow over a bed surface of a complex profile.

Finite-volume numerical method for study shallow water flows over an arbitrary bed profile in the presence of external force is proposed. This method uses the quasi-twolayer model of hydrodynamic flows over a stepwise boundary with advanced consideration of the flow features near the step. A distinctive feature of the suggested model is a separation of a studied flow into two layers in calculating flow quantities near each step, and improving by this means approximation of depth-averaged solutions of the initial three-dimensional Euler equations. We are solving the shallow-water equations for one layer, introducing the fictitious lower layer only as an auxiliary structure in setting up the appropriate Riemann problems for the upper layer. Besides quasi-two-layer approach leads to appearance of additional terms in one-layer finite-difference representation of balance equations. These terms provide the mechanical work made by nonhomogeneous bed interacting with flow. A notable advantage of the proposed method is the consideration of the properties of the process of the waterfall, namely the fluid flow on the step in which the fluid does not wet part of the vertical wall of the step. The presence of dry zones in the vertical part of the step indicates violation of the conditions of hydrostatic flow. The quasi-two-layer approach determines the size of the dry zone of the vertical component of the step. Consequently it gives an opportunity to figure out the amount of flow kinetic energy dissipation on complex boundary. Numerical simulations are performed based on the proposed algorithm of various physical phenomena, such as a breakdown of the rectangular fluid column over an inclined plane, large-scale motion of fluid in the gravity field in the presence of Coriolis force over an mounted obstacle on underlying surface. Computations are made for two dimensional dam-break problem on slope precisely conform to laboratory experiments. Interaction of the Tsunami wave with the shore line including an obstacle has been simulated to demonstrate the effectiveness of the developed algorithm in domains including partly flooded and dry regions.