BSPM

The 3D dynamic model of the plasmasphere [1,2,3] is a semi-empirical model developed by the Solar Wind Division of the Royal Belgian Institute for Space Aeronomy.

Based on physical mechanisms for plasmapause formation and trajectories of particles trapped in the Earth’s magnetic field, it provides the number density and the temperature of the electrons and protons inside and outside the plasmasphere, as well as the position of the plasmapause, as a function of the geomagnetic activity driven by the Kp index. The plasmasphere is eroded during geomagnetic storms and structures like plasma plumes and channels can appear, whereas the ionosphere refills the plasmasphere during quiet times.

The model is coupled to the International Reference Ionosphere (IRI) model to determine the number density and temperatures of the particles between 60 and 700 km of altitude (http://irimodel.org/). The model uses the values at 700 km as boundary conditions to provide the density and temperatures up to 10 Earth radii inside and outside the plasmasphere. The model is running in a near-real-time basis at the SSA (Space Situational Awareness) site of ESA (European Space Agency) using a previous IDL-Fortran version that evaluates the electron density and temperature without the ionosphere coupling and providing animations of the equatorial and meridian plasmasphere dynamics.

In the present implementation, a PYTHON-Fortran version will be used, which is essentially the same model version as the IDL-Fortran one. This implementation will provide only the electron density (at least in the first step) but contains the ionosphere coupling as well as the electron density beyond the plasmapause, i.e., the plasmatrough, recently assessed using new satellite data [4]. Output of the model consists of text files as well as figures for every hour of a simulated day and an animation collecting the figures.

[1] Pierrard, V. and Stegen, K., 2008. A three‐dimensional dynamic kinetic model of the plasmasphere. Journal of Geophysical Research: Space Physics, 113(A10).

[2] Pierrard, V. and Voiculescu, M., 2011. The 3D model of the plasmasphere coupled to the ionosphere. Geophysical Research Letters, 38(12).

[3] Pierrard V., E. Botek and F. Darrouzet, 2021. Improving Predictions of the 3D Dynamic Model of the Plasmasphere, Front. In Astron. Space Sci., 8:681401.

[4] Botek, E., Pierrard, V. and Darrouzet, F., 2021. Assessment of the Earth’s cold plasmatrough modeling by using Van Allen Probes/EMFISIS and Arase/PWE electron density data. Journal of Geophysical Research: Space Physics, 126(12), p.e2021JA029737.

The model requires only one external file input containing Kp values every 3 hours from the previous and the current day of the simulation.    

Running BSPM model will produce, for each hour of the simulation day, the following series of files on the basis of a solar magnetic (SM) coordinates grid:

• two text output files (one for the equatorial plane and one for the meridian plane)
• one figure containing one equatorial and one medirian view as well as the corresponding Kp values.

The text results for the equatorial and meridian planes are separated in two different files that include the radius, magnetic local time, latitude and the density for the corresponding plane. The upper panel in each figure shows the Kp index for the current and previous day of the forecast, providing the geomagnetic activity as predicted on the surface of the Earth during those days. The bottom left panel shows the plasmasphere in the equatorial plane in Solar Magnetic (SM) coordinates. The Earth is shown in the centre of this panel, and the dayside is at the left (12 Magnetic Local Time (MLT)), and the night side is at the right (0 MLT). Thus, the Sun is always assumed to be at the left. The Earth rotates counterclockwise, and the ionosphere and the plasmasphere co-rotates with the Earth. The dawn side is on top (6 MLT) and the dusk side is at the bottom (18 MLT). The axes in the figure have the units of Earth radii (Re). The plasmapause is displayed with empty black dots. The right panel shows the plasmasphere in the meridian plane in SM coordinates. The top of this panel is the magnetic south in the Northern hemisphere and the bottom the magnetic north in the South hemisphere. The left side is the day side (12 MLT) and the night side is at the right (0 MLT). Finally, the figures of whole the day are collected in an animated gif output file.