Applications
Applications
Principal Investigator: Steven A. Curtis, Code 695 NASA/GSFC
Co-Investigators: Daniel S. Spicer, Code 930 NASA/GSFC; Clark M. Mobarry, Code 931 NASA/GSFC; Steven T. Zalesak, Code 931 NASA/GSFC; Kevin M. Olson, University of Chicago; Peter J. MacNeice, Drexel University
The objectives of this investigation are:
Given today's computer resources, magnetohydrodynamics (MHD) is the only physical approximation that can be used for time-dependent three-dimensional (3-D) global modeling of solar wind, magnetosphere, and ionosphere system. This is a computational resources limitation, not a physical one, because critical physical processes occur within boundary layers that are very small relative to the global scales characterizing the solar wind-magnetosphere interaction. The physical problem therefore has greatly disparate spatial and temporal scales. The aforementioned boundary layers are discontinuities in the ideal MHD approximation and require special techniques to model them. Currently we use "shock-capturing" schemes to treat these discontinuities. In general, this approach has been quite successful in predicting the overall morphology and, to a considerable degree, the expected dynamics that result from the solar wind-magnetosphere interaction.
The coupling of these models to a quasi-steady ionospheric model has led to further improvements in the predictive capabilities of these models, as well as basic physical understanding. The major problems with the current MHD models, even within the validity of their approximations, are the inadequate resolution of the boundary regions, the associated unrealistic numerical dissipation, and the lack of proper representation of the ionospheric plasma source. Our Space Physics Theory Program (SPTP) funding is to study the effect on MHD simulation models of spatially resolving these boundary layers and the inclusion of some physical processes at the ion-gyro radius. Use of the HPCC/ESS testbed computer enables us to perform many more simulations that spatially resolve these boundary layers.
The new computational techniques are documented in the PARAMESH Web page, and "A Parallel Adaptive Mesh Refinement Toolkit for the Development of High Performance MHD Models" is to be published in the Proceedings of the Cambridge Symposium of the Physics of Space Plasmas.
We spent the year building and testing ODIN, the new 3-D MHD magnetosphere code with adaptive mesh refinement (AMR), for high performance on the ESS testbed parallel computer. ODIN was built within and extended the programming template of the PARAMESH AMR software package.
ODIN currently includes a 3D MHD simulation region interacting with a 2-D ionosphere. Unique to ODIN is its ability to model daily, as well as seasonal, intrinsic magnetic dipole tilt. ODIN's current science results are validating well with previous results for simple ionospheres and non-tilted magnetic dipoles. In addition, ODIN has been run at very high resolutions that are state of the art in the field.
The next frontier in the global simulation of space plasma systems, such as the terrestrial magnetosphere, requires resolution to the MHD limit and the inclusion of the relevant microphysics in critical regions such as boundary layers. The magnetosphere, with the detailed measurements from the various ISTP, CLUSTER, and future proposed missions such as Grand Tour Cluster, represents a unique opportunity for attaining theory-data closure.
ODIN is providing 3-D MHD simulations of the Earth's magnetosphere with a tilted dipole intrinsic magnetic field. We will continue the development plan of the SPTP proposal, which includes AMR criteria for selected studies, an improved inner magnetosphere model, and extending the physical approximation beyond the ideal MHD.
Clark M. Mobarry
NASA Goddard Space Flight Center
Clark.M.Mobarry.1@gsfc.nasa.gov
301-286-2081
Peter MacNeice
Drexel University
NASA Goddard Space Flight Center
Peter.J.Macneice.1@gsfc.nasa.gov
301-286-2061