Cross-Disciplinary Computational Modeling Throughout the Heliosphere I
Presiding: L Ofman, Catholic University of America; M L Goldstein, NASA
SH11B-01 INVITED 08:30h
Cross-Disciplinary Modeling of Heliospheric Phenomena with the Space Weather Modeling Framework
The Space Weather Modeling Framework (SWMF) aims at providing a high-performance flexible plug-and-play type framework for physics based space weather simulations, as well as for various space physics applications. The SWMF combines numerical models of the Solar Corona, Eruptive Event Generator, Inner Heliosphere, Solar Energetic Particles, Global Magnetosphere, Inner Magnetosphere, Radiation Belt, Ionosphere Electrodynamics and Upper Atmosphere into a high performance coupled model. All the components can be replaced with alternatives, and one can use only a subset of the components. The components are coupled to the control module via standardized interfaces, and an efficient parallel coupling toolkit can be used for the pairwise coupling of the components. The SWMF enables us to do simulations that were not possible with the individual components. Using reasonably high spatial and temporal resolutions in all the coupled components, the SWMF can still run significantly faster than real time on massively parallel supercomputers. This talk presents the design and implementation of the SWMF with a demonstrative application to a space weather event.
SH11B-02 INVITED 08:45h
The Evolution of MHD Modeling: Coupling Local and Global Scales
We will describe how MHD models of the solar corona and inner heliosphere have evolved over the years to include a more comprehensive coupling of local physics (on the scale of active regions and smaller length scales) with global structures (on the solar radius scale). In particular, we will discuss our efforts to understand the thermal and magnetic structure and dynamics of active regions and their coupling to the global structure of the solar corona. We will discuss initiation of CMEs that originate in active regions, and their propagation in the inner heliosphere. Research supported by NASA and the Center for Integrated Space Weather Modeling (an NSF Science and Technology Center).
SH11B-03 09:00h
High-Resolution MHD Simulation of Turbulence Properties of the Solar Wind
The simulation of the evolution of the solar wind suffers from the fundamental limitation that turbulence involves a wide range of spatial scales. Computing power continues to grow exponentially, and thus we are now in a position to improve on our previous simulations by an order of magnitude in overall resolution. We focus on a limited solid angle of solar wind plasma, and use temporally and spatially dependent boundary conditions to simulate a spiral field, shear layers, waves, quasi-two-dimensional fluctuations, and a heliospheric current sheet. Our previous lower-resolution simulations were able to demonstrate the beginnings of an inertial range cascade and showed promising results for the evolution of the Alfvénicity of the fluctuations as compared to observations. We have been unable to reproduce some properties, however, such as the variance directions of the fluctuations relative to the magnetic field direction. The paper will present an update of our progress on this and related problems.
SH11B-04 INVITED 09:15h
Challenges in Modeling the Coupled Magnetosphere-Ionosphere-Thermosphere-Mesosphere System
The success of the Center for Integrated Space Weather Modeling (CISM) depends on the production of an ever-improving series of comprehensive scientific models describing the Solar Terrestrial environment from the solar surface to the upper atmosphere of earth. This requires us to combine existing codes developed to model separate regions and processes to into cohesive models. We require technical solutions capable of the efficient transmission of information among codes, interpolation of quantities between different grids, translation of physical variables between codes with differing physical models, and control mechanisms to synchronize the interaction of codes. We also need to handle the scientific aspects of the interaction of codes with very different physics models, for example, the very different thermodynamic models used in coronal and solar wind codes. We illustrate these challenges we face and our approach toward meeting them from the perspective of our Geospace coupling efforts involving the combination of the Lyon-Fedder-Mobarry (LFM) code, the Rice Convection Model (RCM) code, and the Thermosphere-Ionosphere Nested Grid model (TING). [This work is supported by NSF grant ATM-0120950 and NASA grant NAG5-12652].
SH11B-05 INVITED 09:30h
Multi-species reconnection throughout the Heliosphere
Much progress has been made recently in understanding how reconnection occurs in systems composed solely of electrons and a single ion species. However, reconnection throughout the heliosphere can be much more complex. In the magnetosphere, substantial amounts of O+ can be present due to ionospheric outflows, In the transition region between the solar chromosphere and corona, there can be a substantial neutral population. These multi-species plasmas exhibit reconnection with a much more complicated spatial scale structure than electron-ion reconnection. In the presence of O+, for example, it has recently been confirmed through simulations that a new whistler wave arises at larger length scales. Results from four-fluid simulations (electrons, ions, heavy charged species, and neutrals) will be shown and cross checked with analytical arguments. For the case of O+ in the magnetotail, results from the CIS-CODIF experiment on CLUSTER will be compared with the simulations.
SH11B-06 09:45h
Propagation and motion of bubbles in the geomagnetotail
Entropy-depleted magnetic flux tubes (bubbles) have been observed not only in the Earth's magnetosphere, but also in the magnetospheres of other planets, including Jupiter and Saturn. The motion and evolution of the bubbles are believed to play a crucial role for the global magnetosphere convection of these systems. Birn et al. [2004] studied the propagation of a bubble in the magnetotail and provided a global picture of bubble evolution and dynamics after it is generated. Based on their study, we make further investigations of the motion and dynamic evolution of bubbles in the magnetotail using parallelized and refined 3D MHD simulation model. This new model helps us to achieve a much higher resolution than the previous study, which allows a better exploration of the bubble structures and their evolution. We give a description of detailed 3D bubble structures at different phases of bubble evolution, and find complex patterns across and along the bubble. A detailed force analysis shows that difference MHD forces play different roles at different locations and evolution phases of the bubble, which explains the formation of the special bubble structures. Detailed current structures in the bubble and along the bubble surface are studied and 3D field line geometry is shown to help understand the evolution of the bubble. We further analyze the interactions between the bubble and its surroundings and make comparisons between our results and those from previous studies.