SM52A-01 10:20h
Reconstruction of flux transfer events from Cluster data
The structure of flux transfer events (FTEs), encountered by the Cluster satellites near the northern cusp, is visualized using the Grad-Shafranov reconstruction technique. The method produces a map of the FTE cross section, using combined magnetic field and plasma data from all four spacecraft, under the assumptions that the structures are two-dimensional and time-independent. In a test case, the reconstructed FTE consists of a flux rope with diameter \sim1 $R_{E}$, embedded in the magnetopause. The flux rope is more or less rounded and no signatures of currently active reconnection are found, suggesting that it was created by reconnection at low latitudes and that it had reached an approximate equilibrium by the time Cluster encountered it. The orientation of the flux rope axis can be fairly well determined through a process of optimizing the map, the result being consistent with those from various single-spacecraft methods. Thanks to this, the unambiguous presence of the strong core field is confirmed, providing evidence for component merging. The orientation of the reconnection line at which the flux rope was produced can also be deduced. The amount of the magnetic flux in the flux rope can be calculated from the map and, by dividing it by the time separation between consecutive FTEs, we can estimate a lower limit of the reconnection electric field during the formation of the flux rope. The speed of the flux rope along the magnetopause can be determined and is found to be supersonic relative to the magnetospheric plasma. Maps of other FTEs are also shown and the nature of magnetopause reconnection leading to those FTEs is discussed.
SM52A-02 INVITED 10:35h
Visualizing Three-dimensional Magnetic Reconnection in the Magnetosphere
We address the problem of visualizing three-dimensional magnetic reconnection in the magnetosphere. We present results from calculations of the magnetic skeleton (i.e., the system of magnetic nulls, separator lines and separatrix surfaces which uniquely characterize the magnetic field topology) of the magnetosphere for various IMF orientations. A robust method of locating and tracking magnetic null points is described. The algorithm, based on a bisection method invented by John Greene [J. Comp. Phys., 98, 1992], computes the topological dimension of the magnetic vector field at each cell of the computational grid. The method is very robust, requiring only the values of the magnetic field on the grid points defining each cell. Once the null points are located, we use two separate methods to compute the magnetic separator lines: 1) a shooting method where an initial magnetic seed point is varied until the associated magnetic field line passes as close as possible to one or more of the other nulls; 2) computation of the intersections of the "fan" surfaces associated with the nulls. Three dimensional visualization of the magnetic skeleton, along with isosurfaces of the current density, allow us compare our simulation results to the various competing models of three-dimensional magnetic reconnection in the magnetosphere.
SM52A-03 INVITED 10:55h
Visualization of the Inner Magnetosphere
The inner magnetosphere portion of geospace is the home of the plasmasphere, ring current, plasma sheet, radiation belts, and ionosphere. These plasma populations participate in a complex, coupled, group response to the ever-changing geomagnetic conditions. The past few years have seen the rise of routine global imaging of the inner magnetosphere through utilization of ultraviolet, neutral atom, and radar-based remote sensing techniques realized for the IMAGE mission. At the same time, we continue to have excellent multiple sources of in situ observations (e.g., DMSP, Polar, LANL, Cluster) and ground-based remote-sensing capabilities (e.g., radar, magnetometer, and TEC). The remote-sensing data provide a means of tying all the available in situ observations into a coherent picture of the global coupled response of the inner magnetosphere, if proper visualization techniques are developed. Visualization tools to represent plasma flows, electric fields, fluxes, and densities exist, but they need to be used together in new ways. I will present several visualization tools that have proved fruitful in the study of the inner magnetosphere, including overlay of in situ data onto images, extraction of profiles from images, magnetic mapping of images and/or ground-based observations, and multi-instrument composite images.
http://enarc.space.swri.edu/VISUALIZATION/
SM52A-04 INVITED 11:15h
Next Generation Data Mining and Visualization Techniques: Application to Global Hybrid Simulations
Global hybrid simulations, in which electrons are treated as a fluid and ions kinetically, provide high resolution "images" of the magnetosphere on ion temporal and spatial scales. Visualization and analysis of data from these simulations pose serious challenges that need to be addressed. For example, a typical global 2-D simulation run generates over 100 Gb of data even when individual particle data are saved much less frequently than moments and field data. A 3-D global run easily generates over TB of data. Due to their large size, these data sets are often stored in segments over distributed platforms. An added complication is that no off-the-shelf software exists and packages such as IDL, OpenDx and VTK require significant customization. In this talk, we provide an overview of our customized software and illustrate their usage through examples. In particular, three aspects of data analysis techniques are described in some detail. One, has to do with tools developed for visualization of data in various perspectives and application of standard analysis techniques to them. The other, involves the use of intelligent software for data mining and event identification purposes. Third, is the development of special software to facilitate comparison between simulation and spacecraft data. In all cases, we place our focus on bow shock or magnetopause related processes.
SM52A-05 11:35h
Use of Animation for the Visualization of Large-Scale ULF Waves in the Magnetosphere
ULF waves can be simulated by magnetospheric MHD models. These waves are best visualized through animation of the model output. Most importantly, this approach allows the elucidation of the global morphology of ULF poloidal as well as toroidal waves with a multiplicity of modes and harmonics. We will present output animation from one or more runs of the BATS-R-US model where the model input is a synthetic solar wind wave train with oscillations in the solar wind proton density at ULF frequencies. We will show how the observed wave morphology can shed light on the acceleration of energetic electrons.
SM52A-06 11:50h
Visualization and Science Analysis for the CISM Models
The Center for Integrated Space Weather Modeling (CISM) is working on developing a model from the surface of the sun to the Earth's ionosphere. Among the many challenges facing this program is the development of visualization and data analysis package which can be used to examine the results from all of the component models. The CISM DX pacakge is a collection of data, models, and tools for analysis and visualization. One component of the package is SPDX, which extends the capabilities of the open source visualization package, OpenDX, into the space physics domain through a series of custom modules for importing data and visual programs for producing visualizations of the results as well as assisting in the analysis of the simulation results. In this presentation we will present highlights from the ongoing visualization and data analysis efforts for each of the key component models within CISM physics based modeling chain. Results from the MAS solar corona model will show how these tools allow for determination of regions of open and closed flux and comparison with observations. The solar wind model ENLIL, will be used to demonstrate the structure and dynamics of the heliospheric current sheet. We will also show how this package allows for easy tracing of magnetic field lines between the two models when the models are coupled together. Results from the magnetospheric simulation, LFM, will highlight two important aspects visualization and science analysis. In the first, results from the exploration of structure of the magnetic field and current systems in the magnetosphere obtain by students in the CISM Space Weather Summer School using the ability to interactively trace field lines. Secondly, the flow of energy and momentum within the magnetosphere during the onset of a magnetospheric substorm is studied by using the package to define regions like the plasma sheet and lobes. The CISM DX package is available for use beyond the CISM team and forms the basis of a very powerful visualization and data analysis toolkit.
SM52A-07 12:05h
Scientific visualizations through the Web at CCMC
Scientific visualization is an essential part of the day-to-day operation of the Community-Coordinated Modling Center (CCMC). Web-based visualization of over 10 Solar coronal, heliospheric, magnetospheric and ionospheric models is provided with an ever increasing wealth of analysis tools. Scientists in the community can request simulation runs that can be thoroughly analyzed through the web. This presentation provides an overwiew of the capabilities provided at CCMC website and major research studies that were performed with the help of the visualization tools. Standardization of model outputs into the visualization program package is now implemented via read modules that read individual models' output. We are working on a conversion to a self-describing data format that facilitates system-independent ingestion of model outputs into the visualization and transfer of model output files to other computing systems (i.e. at a user's request).