High-Resolution Empirical Reconstruction of the Geomagnetic Field as a Space Weather Research Tool

Johns Hopkins University, Baltimore MD

Investigators

Abstract

Data-based modeling and forecasting of the geomagnetic field is a key element of space weather research. Storm and substorm perturbations of the Earth's main magnetic field are among the main indicators of space weather disturbances, and they also help assess other effects such as particle precipitation and plasma heating. A dramatic increase in the amount of data for the terrestrial magnetosphere has made possible a new generation of empirical geomagnetic field models with much larger numbers of degrees of freedom and sophisticated data-binning techniques. A set of the corresponding data-binning, data-fitting and visualization procedures known as the TS07D model is available and widely used in magnetospheric applications. In the project the TS07D model will be improved in three critical aspects. First, the data-binning process will be optimized to achieve a balance between the number of system-level parameters, such as the solar wind electric field, and their forecasting accuracy. As a part of this task the data-binning method will be tested as a pattern-recognition tool, which helps reveal new classes of magnetic storms such as the storms that include saw tooth events. Second, the model output in the form of the effective hot plasma pressure inferred by assuming static force balance for an isotropic plasma will be investigated. The inferred pressure can be used in global MHD models to improve the plasma equation of state and to describe the ring current buildup and decay. It can also be used for the improvement of external boundary conditions in kinetic ring current models, as well as for direct comparison with global plasma patterns retrieved from the energetic neutral atom imaging of the inner magnetosphere. Third, a modification of the field-aligned current part of the model will be studied to transform it into a flexible set of current modules whose foot-point distributions are consistent with low-altitude observations. The model will also be rewritten as a single-language code assuming different platforms and multi-thread operations on computer clusters. The results of this investigation will be an improved magnetospheric magnetic field model. While direct research with the model described above will be valuable, the model will have an even greater value. Magnetospheric magnetic field models are widely used in other applications in magnetospheric physics by other researchers. Since phenomena occurring in different parts of the magnetosphere and the ionosphere are coupled by the magnetic field the model can be used to map phenomena between these two regions. The models can be used to determine the trajectories of charged particles. Finally they can be used to give an investigator an estimate of the magnetic fields in regions where they do not have observations.