Volcanic plume simulation on large scales

摘要: Abstract The plume model ATHAM (Active Tracer High Resolution Atmospheric Model) is designed to simulate explosive volcanic eruptions for a given mass flux of pyroclastic material under realistic atmospheric background conditions. Based on the assumption that all particles are small model's equations simplified such that, besides gaseous, liquid and solid constituents arbitrary concentrations, only volume means momentum heat predicted. exchange between fluid's treated diagnostically. A prognostic turbulence closure scheme describing entrainment ambient air into takes account anisotropy horizontal vertical components turbulence. Its length scale assumed be isotropic. Microphysical processes as dry air, water vapor, cloud water, precipitable ice crystals graupel parameterized. Ash lapilli represent spectrum silicate particles. diagnostic sedimentation velocity allows separation gas formulated with an implicit time stepping scheme. motion transport tracers in form order guarantee conservation tracer masses. equation advective form. wave momentum, solved using combined line-relaxation successive overrelaxation Two-dimensional experiments symmetric cases cylindrical coordinates yield qualitatively similar results other dynamic–thermodynamic models. However, now computed quantitatively through condensed matter has sophisticated description. In study transferability from computationally cheap two-dimensional costly three-dimensional simulations plume, comparisons calculations without performed. Finally, different conditions allow investigation development influence cross wind effects, temperature humidity profiles.