HLRB Project pr48ca

Global High-Resolution Earth Models - Generation and Assessment

Department of Earth and Environmental Sciences (Geophysics), LMU

Global High-Resolution Earth Models - Generation and Assessment

Department of Earth and Environmental Sciences (Geophysics), LMU

Department of Earth and Environmental Sciences (Geophysics), LMU

Dr. Bernhard Schuberth

Theresienstr. 41

80333 München

Much of what one refers to as geological activity of the Earth arises from convective processes within the Earth’s mantle that transport heat from the deep interior of our planet to the surface. It is common to use the term circulation to describe the motion of the mantle, in analogy to the general circulation of the oceans and atmosphere. One of the major challenges in the geosciences is to constrain the distribution and magnitude of the resulting vast forces that drive plate tectonics (a process well known but poorly understood). Mantle flow also provides boundary conditions - thermal and mechanical - to other key elements of the Earth system (e.g., geodesy, geodynamo/geomagnetism). This makes fluid dynamic studies of the mantle essential to our understanding of how the entire planet works.In this long-term effort, we strive for improved computational models of the Earth's deep interior. The general work-flow involves the generation of new models of mantle convection with either updated sets of input parameters or increased resolution and improved numerical representation. The crucial step is then to assess the quality of these models against observations made of the Earth system (including geologic, seismological and geodetic information). This involves two additional sets of simulations. First, the inverse modelling of mantle convection that allows one to track mantle motion back into the past. This way, one can test unknown parameters of the geodynamic models explicitly against constraints gleaned from geologic observations. Second, the simulation of 3-D global seismic wave propagation through the geodynamic models, which enables us to test the models directly against the huge amount of seismic data available nowadays.Our numerical simulations of mantle dynamics and seismic wave propagation place formidable demands on parallel computing resources, as they require extremely high resolutions in space and time. This places them in the realm of grand challenge applications in the computational sciences. Forward problems solve conservation equations for mass, momentum and energy or the seismic wave equation on computational grids with billions of degrees of freedom (DOF) and thousands of time steps. Moreover, the inverse problem of mantle convection demands a number of iterations on the forward-inverse cycle, making the calculations very CPU-time intense. In addition, the inverse simulations require very large parallel storage and I/O capacity, as one must preserve on the order of one billion degrees of freedom per time step over the entire simulation period.

Impressum, Conny Wendler