HR: 0830h
AN: GP11A-0250    [PDF]
TI: Modular Approaches to Earth Science Scientific Computing: 3D Electromagnetic Induction Modeling as an Example
AU: * Tandon, K
EM: kush@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University Oceanogrpahy Admin. Bldg. 104, Corvallis, OR 97331 United States
AU: Egbert, G
EM: egbert@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University Oceanogrpahy Admin. Bldg. 104, Corvallis, OR 97331 United States
AU: Siripunvaraporn, W
EM: scwsp@mahidol.ac.th
AF: Mahidol University, Department of Physics Faculty of Science Rama 6 Rd., Bangkok, 10400 Thailand
AB: We are developing a modular system for three-dimensional inversion of electromagnetic (EM) induction data, using an object oriented programming approach. This approach allows us to modify the individual components of the inversion scheme proposed, and also reuse the components for variety of problems in earth science computing howsoever diverse they might be. In particular, the modularity allows us to (a) change modeling codes independently of inversion algorithm details; (b) experiment with new inversion algorithms; and (c) modify the way prior information is imposed in the inversion to test competing hypothesis and techniques required to solve an earth science problem. Our initial code development is for EM induction equations on a staggered grid, using iterative solution techniques in 3D. An example illustrated here is an experiment with the sensitivity of 3D magnetotelluric inversion to uncertainties in the boundary conditions required for regional induction problems. These boundary conditions should reflect the large-scale geoelectric structure of the study area, which is usually poorly constrained. In general for inversion of MT data, one fixes boundary conditions at the edge of the model domain, and adjusts the earth?s conductivity structure within the modeling domain. Allowing for errors in specification of the open boundary values is simple in principle, but no existing inversion codes that we are aware of have this feature. Adding a feature such as this is straightforward within the context of the modular approach. More generally, a modular approach provides an efficient methodology for setting up earth science computing problems to test various ideas. As a concrete illustration relevant to EM induction problems, we investigate the sensitivity of MT data near San Andreas Fault at Parkfield (California) to uncertainties in the regional geoelectric structure.
DE: 0619 Electromagnetic theory
DE: 0644 Numerical methods
DE: 0925 Magnetic and electrical methods
DE: 1515 Geomagnetic induction
DE: 3914 Electrical properties
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting