Abstract
AbstractBoth ground and space observations are used extensively in the modeling of space weather processes within the Earth’s magnetosphere. In radiation belt physics modeling, one of the key phase‐space coordinates is L*, which indicates the location of the drift paths of energetic electrons. Global magnetic field models allow a subset of locations on the ground (mainly subauroral) to be mapped along field lines to a location in space and transformed into L*, provided that the initial ground location maps to a closed drift path. This allows observations from ground, or low‐altitude space‐based platforms to be mapped into space in order to inform radiation belt modeling. Many data‐based magnetic field models exist; however, these models can significantly disagree on mapped L* values for a single point on the ground, during both quiet times and storms. We present a state of the art probabilistic L* mapping tool, Pro‐L*, which produces probability distributions for L* corresponding to a given ground location. Pro‐L* has been calculated for a high resolution magnetic latitude by magnetic local time grid in the Earth’s Northern Hemisphere. We have developed the probabilistic model using 11 years of L* calculations for seven widely used magnetic field models. Usage of the tool is highlighted for both event studies and statistical models, and we demonstrate a number of potential applications.
Highlights
The operational and research-focused modeling of high-energy electron fluxes in Earth’s radiation belts is based upon the physics of electron motion in the Earth’s magnetic field
Since a dipole approximation is sufficient for low latitudes, and moderately high latitudes experience mostly open field lines, we focus on magnetic latitudes in Altitude-Adjusted Corrected Geomagnetic (AACGM) coordinates that map to the dipole L range L = 2.5–10, with 0.5 L spacing
Global L* median and interquartile range (IQR) maps for each magnetic field model are shown in Figures 2 and 3
Summary
The operational and research-focused modeling of high-energy electron fluxes in Earth’s radiation belts is based upon the physics of electron motion in the Earth’s magnetic field. Models of radiation belt dynamics use a coordinate system based upon these motions, which can be described using a system of adiabatic invariants μ, J, and L*. This means that slow, reversible changes to the energy and path of electrons due to slow changes in the magnetic field are automatically taken into account in the model, since the computational grids themselves are based upon the invariant. The creation of initial conditions, boundary conditions (e.g., Glauert et al, 2018), diffusion matrices (e.g., Horne et al, 2018), THOMPSON ET AL
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