The German Weather Service (Deutscher Wetterdienst) has recently developed a new operational global numerical weather prediction model, named GME, based on an almost uniform icosahedral–hexagonal grid. GME gridpoint approach avoids the disadvantages of spectral techniques as well pole problem in latitude–longitude grids and provides data structure extremely suited to high efficiency distributed memory parallel computers. formulation discrete operators for this grid is described evaluations...

Mantle convection is influenced simultaneously by a number of physical effects: brittle failure in the surface plates, strongly variable viscosity, mineral phase changes, and both internal heating (radioactivity) bottom from core. Here we present systematic study three potentially important depth‐dependent an endothermic change, versus heating. We model three‐dimensional spherical at Rayleigh Ra =10 8 thus approaching dynamical regime mantle. An isoviscous, internally heated reference...

We present an almost uniform triangulation of the two-sphere, derived from icosahedron, and describe a procedure for discretization partial differential equation using this triangular grid. The accuracy our is described by strong theoretical estimate, verified large-scale numerical experiments. also data structure spherical that allows fast computation on either vector computer or asynchronous parallel computer.

Earth's near‐surface layer, its lithosphere, is broken into quasi‐rigid plates that form the upper thermal boundary layer for mantle convection. Since discovery of plate tectonics, it has been widely conjectured but only recently demonstrated this peculiar style convection may be facilitated by an low viscosity zone (LVZ) over which glide easily. The LVZ, or “asthenosphere,” concept dates from 19th century investigations isostatic support mountain belts and supported modern evidence a...

Computer models of mantle convection constrained by the history Cenozoic and Mesozoic plate motions explain some deep-mantle structural heterogeneity imaged seismic tomography, especially those related to subduction. They also reveal a 150-million-year time scale for generating thermal in mantle, comparable record motion reconstructions, so that problem unknown initial conditions can be overcome. The pattern lowermost structure at core-mantle boundary is controlled subduction history,...

A new approach to climate simulation uses geodesic grids generated from an icosahedron and could become on attractive alternative current models. We implemented atmospheric general circulation model using a discretization of the sphere. Our message-passing interface runs efficiently massively parallel machines.

Data assimilation is an approach to studying geodynamic models consistent simultaneously with observables and the governing equations of mantle flow. Such essential in circulation models, where we seek constrain unknown initial condition some time past, thus cannot hope use first-principles convection calculations infer flow history mantle. One most important for mantle-flow comes from Mesozoic Cenozoic plate motion that provide constraints not only on surface velocity but also evolution...

Delamination of the lithospheric thermal boundary from overlying continental crust propagates laterally line initiation, accelerating as sinking slab detached lithosphere grows longer. This propagation has been numerically modeled with steady state equations in a moving reference frame by matching an interior finite element solution to flexible conditions which represent mechanical and response surroundings. The form depends on shear coupling intruding asthenosphere top across thin layer...

Thermally driven convection within the earth’s mantle determines one of longest time scales our planet. Plate tectonics, piecewise continuous movement surface, is prime manifestation this slow deformational process but ultimately all large scale geological activity and dynamics planet involves release potential energy in mantle. Massively parallel supercomputers are now allowing us to construct models with unprecedented complexity realism. Here we present results from an approach computation...

Abstract A comparison is made between seven different numerical methods for calculating two-dimensional thermal convection in an infinite Prandtl number fluid. Among the are finite difference and element techniques that have been used to model Earth's mantle. We evaluate performance of each method using a suite four benchmark problems, ranging from steady-state intrinsically time-dependent with recurring boundary layer instabilities. These results can be determine accuracy other...

Tharsis province is a major center of Martian volcanic activity characterized by large gravity and topography anomalies. The origin debated. One hypothesis that the was produced melting associated with mantle plume from core‐mantle boundary. An alternative formed an impact. Recent studies have shown this plausible geodynamical point view long‐lived impact plumes might play role in areoid evolution. In study, magmatic evolution impact‐induced thermochemical investigated fully...

Seismic evidence suggests that the solid inner core of Earth may be anisotropic. Several models have been proposed to explain this anisotropy as result preferred orientation crystals. They range from a large annealed single crystal, growth at melt interface, deformation‐induced texture. In study texture development by deformation during convection is explored for ε‐iron (hcp) and γ‐iron (fcc). Convection patterns harmonic degree two were investigated in detail. model it assumed traces...

We calculate polar motion in models of 3‐D spherical mantle convection at Rayleigh numbers up to 10 8 which include internal heating, radial viscosity variations, and an endothermic phase change. Isoviscous yield rapid order 3°/Myr, but a factor 30 increase with depth reduces the rate about 0.5°/Myr due stabilization large‐scale pattern convection. Avalanching change causes pulsating inertial interchange excursions 80–110° duration 20–70 Myr. A layered model yields only one event 600 million...

Ongoing deformation of southern California is simulated in a set 63 models an attempt to empirically determine fault friction. To previous code for simulation anelastic crustal strain, we introduce new finite element represent curved arbitrary rheology. We also add several selfconsistent patterns horizontal drag on the base crust caused by independent upper mantle flow. A grid isoparametric elements represents regional geometry and known variations elevation heat Plate tectonic velocity...

A number of geophysical arguments point out the possibility that global mantle convection could have been extremely sluggish or even absent during a large part Martian history. This implies early thermal anomalies produced planetary formation might not quickly erased by vigorous convection. One likely mechanism inhomogeneity is impacts at end heavy bombardment. We suggest Tharsis province be related to such an impact‐induced anomaly rather than convective plume. The shape present‐day geoid...