Radbelt

Radbelt: Work in progress to refactor the AE-8/AP-8 Van Allen belt model.

Status

Compiling

A Fortran Package Manager manifest file is included, so that the library and test cases can be compiled with FPM. For example:

fpm build --profile release
fpm test --profile release

To use radbelt within your fpm project, add the following to your fpm.toml file:

[dependencies]
radbelt = { git="https://github.com/jacobwilliams/radbelt.git" }

Documentation

The latest API documentation can be found here. This was generated from the source code using FORD.

Original source

• The original sourcecode was hosted at GSFC "Modelweb", an archive of which can be found here. It is presumed to be in the public domain. Reference: National Space Science Data Center, Data set PT-11B, Mar 1996. Dieter Bilitza, GSFC/NSSDC code 633, Greenbelt, MD 20771.

See also

• NASA ModelWebArchive Archive (IGRF)
• NASA ModelWebArchive Archive (RADBELT)
• International Geomagnetic Reference Field
• An Astropy-friendly wrapper for the AE-8/AP-8 Van Allen belt model
• pyIGRF
• https://github.com/lanl/RAM-SCB/blob/master/srcExternal/igrf.f
• https://github.com/space-physics/igrf/blob/main/src/igrf/fortran/igrf13.f

Test case

See the radbelt_test.f90 and test.py files:

Code | Runtime (sec) | Cases per second --- | --- | --- Python version | 3.514 | 409 Fortran Function version (get_flux()) | 1.622 | 1198 Fortran Class version (radbelt_type%get_flux()) | 0.017 | 112259

The main difference in speed from using the class method is that the data files are only read once, rather than each time the function is called (which is done in the other two versions).

Brief description

These empirical models describe the differential or integral, omnidirectional fluxes of electrons (AE-8) and protons (AP-8) in the inner and outer radiation belts (electrons: L=1.1 to 11, protons: L=1.1 to 7) for two epochs representing solar maximum (1970) and minimum (1964) conditions. The energy spectrum ranges from 0.1 to 400 MeV for the protons and from 0.04 to 7 MeV for the electrons. AE-8 and AP-8 are the most recent ones in a series of models established by J. Vette and his colleges at NSSDC starting in the early sixties. The models are based on almost all available satellite data. It is IMPORTANT that the models maps for solar maximum are used with a magnetic field model for epoch=1970 and for solar minimum for epoch=1964.

For each epoch and particle the model consists of a three- dimensional table of (logarithm of) particle fluxes in energy, L-value, and B/B0 (magnetic field strength normalized to the equator). The program MODEL finds the particle fluxes for given energy, L-value and B/B0 by interpolating in energy (subroutine TRARA1) and in L * B/B0 space (TRARA2). The program RADBELT produces tables of integral or differential fluxes for different energies varying with L or B/B0.

The coefficient files are provided in ASCII (*.asc) format:

Description | Filename | Size (KB) --- | --- | --- AE-8, epoch 1970, solar maximum | ae8max.asc | 84 AE-8, epoch 1964, solar minimum | ae8min.asc | 81 AP-8, epoch 1970, solar maximum | ap8max.asc | 101 AP-8, epoch 1964, solar minimum | ap8min.asc | 102

In March 1995 the earlier used compressed model maps AP8MIC and AP8MAC were replaced with the full maps AP8MIN/MAX with the help of D. Heynderickx (BIRA, Brussel, Belgium) and A. Beliaev (INP/MSU, Moscow, Russia). Heynderickx and Beliaev (1995) had found and corrected a small error in the AP8MIN map; two lines had been exchanged.

References

• G.W. Singley, and J.I. Vette, The AE-4 Model of the Outer Radiation Zone Electron Environment, NSSDC/WDC-A-R&S 72-06, 1972.
• M.J. Teague, and J.I. Vette, A Model of the Trapped Electron Population for Solar Minimum (AE-5), NSSDC/WDC-A-R&S 74-03, 1974.
• M.J. Teague, K.W. Chan, and J.I. Vette, AE-6: A Model Environment of Trapped Electrons for Solar Maximum, NSSDC/WDC-A-R&S 76-04, 1976
• D.W. Sawyer, and J.I. Vette, AP-8 Trapped Proton Environment for Solar Maximum and Minimum, NSSDC/WDC-A-R&S 76-06, 1976.
• J.I. Vette, K.W. Chan, and M.J. Teague, Problems in Modeling the Earth's Trapped Radiation Environment, AFGL-TR-78-0130, 1978.
• K.W. Chan, M.J. Teague, N.J. Schofield, and J.I. Vette, Modeling of Electron Time Variation in the Radiation Belts, p. 121-149, in: Quantitative Modeling of Magnetospheric Processes, W.P. Olson (ed.), geophysical monograph 21, American Geophysical Union, 1979.
• M.T. Teague, N.J. Schofield, K.W. Chan, and J.I. Vette, A Study of Inner Zone Electron Data and their Comparison with Trapped Radiation Models, NSSDC/WDC-A-R&S 79-06, 1979.
• J.I. Vette, The AE-8 Trapped Electron Model Environment, NSSDC/WDC-A-R&S 91-24, 1991.
• J.I. Vette, The NASA/National Space Science Data Center Trapped Radiation Environment Model Program (1964-1991), NSSDC/WDC-A-R&S 91-29, 1991.
• D. Heynderickx and A. Beliaev, Identification of an error in the distribution of the NASA model AP-8 MIN, J. Spacecraft and Rockets 32, 190-192, 1995.