Юдин М.С.  

Dynamics of mesoscale gravity flows in the atmosphere


M. S. Yudin
ICMMG SB RAS, Novosibirsk



            A two-dimensional finite-element model and a three-dimensional finite-difference model in the Boussinesq approximation are used to study the retardation of cold atmospheric fronts by mesoscale obstacles of various shapes and slopes [1], [2].The model input data are specified with an analytical model for an idealized front. The finite-difference model is used for relatively smooth terrain, while the finite-element model is developed for steep slopes. Both models are based on the compressible Navier-Stokes equations with a special procedure of filtering the spurious noises.Various types of stratification are used in the simulations.
            The model results are compared with analytical solutions to a shallow water equation model and results of finite-difference simulations in three dimensions [3] and in two-dimensional cases [4]. At neutral stratification the speed of front propagation calculated by the two-dimensional model agrees with an empirical formula and simulation results reported in [4]. The results of two dimensional finite-element simulations show the formation of hydraulic jumps on the front surface, which is in agreement with existing theories and the results of finite-difference simulations obtained in [4].

             This study was supported by the Presidium of RAS, under Program 43, and the Russian Foundation for Basic Research, under Grant 14-01-00125-a.
1. Yudin, M.S. and Wilderotter, K., "Simulating atmospheric flows in the vicinity of a water basin," Computational Technologies, 11, 128-134 (2006).
2. Yudin, M.S., "Comparison of FDM and FEM models for a 2D gravity current in the atmosphere over a valley,"Bull. Novos. Comput. Center, 13, 95-101(2012).
3. Schumann, U., "Influence of mesoscale orography on idealized cold fronts," J. Atmos. Sci., 44, 3423-3441 (1987).
4. Bischoff-Gauss, I., Gross, G. and Wippermann, F., "Numerical studies on cold fronts. Part 2: Orographic effects on gravity flows," Meteorol.  Atmos. Phys., 40, 159-169 (1989).s on gravity flows," Meteorol.  Atmos. Phys., 40, 159-169 (1989).

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