IRBEM wraps several widely used empirical radiation belt and space environment models, allowing users to compute particle fluxes along spacecraft trajectories or at arbitrary magnetic coordinates. All flux models share a common interface: you specify a model identifier (Documentation Index
Fetch the complete documentation index at: https://mintlify.com/PRBEM/IRBEM/llms.txt
Use this file to discover all available pages before exploring further.
whichm), a flux type (whatf), energy levels, and either spacecraft positions or magnetic coordinates.
AE8 and AP8 Models
NASA’s AE8 and AP8 models are the long-standing standard for trapped electron and proton flux estimates in the inner magnetosphere. AE8 covers electrons; AP8 covers protons. MIN/MAX variants correspond to solar-minimum and solar-maximum conditions.Both
FLY_IN_NASA_AEAP and GET_AE8_AP8_FLUX support the ESA interpolation scheme described in Daly et al. (1996) for improved accuracy at low altitudes. Activate it by using negative values for whichm (e.g., -1 for AE8 MIN with ESA interpolation).FLY_IN_NASA_AEAP
Fly a spacecraft through the AE8 or AP8 model and return fluxes along the entire trajectory. Position inputs are given as arrays of spacecraft coordinates in the user-selected coordinate system.Parameters
Number of time points (up to
NTIME_MAX).Key for the input coordinate system. See the coordinate systems reference.
Selects the radiation model:
| Value | Model |
|---|---|
1 | AE8 MIN |
2 | AE8 MAX |
3 | AP8 MIN |
4 | AP8 MAX |
-1 | AE8 MIN — ESA interpolation |
-2 | AE8 MAX — ESA interpolation |
-3 | AP8 MIN — ESA interpolation |
-4 | AP8 MAX — ESA interpolation |
Type of flux output:
| Value | Type |
|---|---|
1 | Differential flux at energy E1 (MeV⁻¹ cm⁻² s⁻¹) |
2 | Flux within E1–E2 energy range (MeV⁻¹ cm⁻² s⁻¹) |
3 | Integral flux above E1 (cm⁻² s⁻¹) |
Number of energy channels.
Energy levels in MeV. First row is E1, second row is E2. When
whatf is 1 or 3, E2 is not used.Year for each time point.
Day of year for each time point (January 1st = 1).
Universal time in seconds for each time point.
First coordinate of spacecraft position according to
sysaxes.Second coordinate of spacecraft position.
Third coordinate of spacecraft position.
Output
Particle flux values for each time point and energy channel, in units determined by
whatf.Call Sequences
GET_AE8_AP8_FLUX
Compute AE8 or AP8 flux at specified magnetic coordinates (B/B₀ and L) without following a spacecraft trajectory. TheBBo and L inputs replace the time-and-position inputs of FLY_IN_NASA_AEAP.
Parameters
Number of positions (up to
NTIME_MAX).Model selection — same values as
FLY_IN_NASA_AEAP (1–4, or −1 to −4 for ESA interpolation).Flux type — same values as
FLY_IN_NASA_AEAP (1, 2, or 3).Number of energy channels.
Energy levels (MeV). E2 is ignored when
whatf is 1 or 3.B/B₀ (field magnitude divided by equatorial field magnitude) for each position.
McIlwain L-shell parameter for each position.
Output
Flux values for each position and energy channel.
Call Sequences
AFRL CRRES Models
The CRRES (Combined Release and Radiation Effects Satellite) models from the Air Force Research Laboratory describe trapped proton and electron fluxes measured during the CRRES mission (1990–1991). CRRESELE covers electrons; CRRESPRO covers protons.Both CRRES routines require the CRRES data files. You must provide the full path to the directory containing these files via the
path/crres_path parameter. In the MATLAB wrapper, onera_desp_lib_fly_in_afrl_crres searches for crrespro_quiet.txt on the MATLAB path.FLY_IN_AFRL_CRRES
Fly a spacecraft through the CRRESPRO or CRRESELE models and return fluxes along the trajectory.Parameters
Number of time points (up to
NTIME_MAX).Key for the input coordinate system.
Selects the CRRES model:
| Value | Model |
|---|---|
1 | CRRESPRO QUIET |
2 | CRRESPRO ACTIVE |
3 | CRRESELE AVERAGE |
4 | CRRESELE WORST CASE |
5 | CRRESELE Ap15 |
Flux type:
1 = differential, 2 = energy-range, 3 = integral.Number of energy channels.
Energy levels (MeV).
Year for each time point.
Day of year for each time point.
Universal time in seconds.
First coordinate per
sysaxes.Second coordinate.
Third coordinate.
Preceding 15-day running average of the Ap index with a one-day delay. Only used when
whichm = 5 (CRRESELE Ap15); ignored otherwise.Full path to the directory containing CRRES model data files, as a byte array.
Length of the
path string.Output
Flux values for each time and energy channel.
Call Sequences
GET_CRRES_FLUX
Compute CRRES flux at specified B/B₀ and McIlwain L positions.Number of positions (up to
NTIME_MAX).Model selection — same values as
FLY_IN_AFRL_CRRES (1–5).Flux type:
1 = differential, 2 = energy-range, 3 = integral.Number of energy channels.
Energy levels (MeV). E2 is ignored when
whatf is 1 or 3.B/B₀ for each position.
McIlwain L for each position.
15-day running average Ap (used only for
whichm = 5).Path to CRRES data files.
Length of path string.
Flux values for each position and energy channel.
Other Radiation Models
FLY_IN_IGE — International Geostationary Electron Model
FLY_IN_IGE computes the electron flux environment at geostationary orbit using the IGE (International Geostationary Electron) model family, developed from LANL-GEO (1976–2006) and JAXA-DRTS data. Three model versions are available:
| Key | Name | Energy Coverage | Year |
|---|---|---|---|
1 | POLE-V1 | 30 keV – 1.3 MeV | 2003 |
2 | POLE-V2 | 30 keV – 5.2 MeV | 2005 |
3 | IGE-2006 | 0.9 keV – 5.2 MeV | 2006 |
Use is restricted to geostationary altitude, as the model is derived from GEO measurements. The model accepts a mission launch year and duration rather than trajectory positions.
Parameters
Year of spacecraft start of life in orbit.
Mission duration in years.
Model selection:
1 = POLE-V1, 2 = POLE-V2, 3 = IGE-2006.Flux type:
1 = differential, 2 = energy-range, 3 = integral.Number of energies. Set to
0 to use the default energy grid (returned in Nene; allocate at least 50 elements in all Nene-sized arrays).Energy levels (MeV).
Output
Lower-envelope flux across the solar cycle, averaged over the mission duration.
Mean expected flux averaged over the mission duration.
Upper-envelope flux including energy-dependent margins; use for conservative design.
Call Sequences
FLY_IN_MEO_GNSS — MEO GNSS Electron Model
FLY_IN_MEO_GNSS computes the electron environment at Medium Earth Orbit (MEO) / GNSS altitudes (~20,000 km, 55° inclination), using LANL-GPS data from 1990 to 2006.
| Key | Name | Energy Coverage | Notes |
|---|---|---|---|
1 | MEO-V1 | 280 keV – 1.12 MeV | No solar cycle variation; use for 11-year averages |
2 | MEO-V2 | 280 keV – 2.24 MeV | Issued 2007 |
Parameters
Year of spacecraft start of life.
Mission duration in years.
Model:
1 = MEO-V1, 2 = MEO-V2.Flux type:
1, 2, or 3.Number of energies;
0 for defaults (allocate ≥50 elements).Energy levels (MeV).
Output
Lower-envelope flux for the mission duration.
Mean expected flux.
Upper-envelope flux with margins.
Effect Models
SHIELDOSE-2 — Space-Shielding Radiation Dose
SHIELDOSE-2 (Seltzer, 1994) calculates absorbed dose as a function of aluminium shielding depth, given incident electron and proton fluence spectra. It handles three shield geometries:- Semi-infinite plane medium (dose vs. depth, irradiation from one side)
- Transmission surface of a finite plane slab (vs. slab thickness)
- Centre of a solid sphere (vs. sphere radius; returns ½ the full-sphere dose)
Parameters
Detector material:
1=Al, 2=Graphite, 3=Si, 4=Air, 5=Bone, 6=Calcium Fluoride, 7=Gallium Arsenide, 8=Lithium Fluoride, 9=Silicon Dioxide, 10=Tissue, 11=Water.Nuclear interactions in aluminium:
1=no attenuation, 2=attenuation with local secondary energy deposition, 3=attenuation with secondary deposition plus approximate neutron dose.Number of shielding depth points (up to 71). Values close to 71 are recommended for accurate semi-infinite and sphere geometry results.
Shielding depth units:
1=mils, 2=g/cm², 3=mm.Shielding thickness values in the units specified by
iunt.Min/max energy of solar proton spectrum (MeV).
Min/max energy of trapped proton spectrum (MeV).
Min/max energy of trapped electron spectrum (MeV).
Number of integration points for proton/electron spectrum integration. A value of
1001 is recommended.Number of spectrum points for solar protons / trapped protons / trapped electrons (max 301 each).
Unit conversion factor from /energy to /MeV (e.g.,
1000 if flux is in /keV).Mission duration as a multiple of unit time (seconds).
Solar proton spectrum: energies (MeV) and fluences (/energy/cm²).
Trapped proton spectrum: energies (MeV) and omnidirectional flux (/energy/cm²/s).
Trapped electron spectrum: energies (MeV) and omnidirectional flux (/energy/cm²/s).
Output
Each dose array has shape[71, 3] where the three columns correspond to: (1) semi-infinite medium, (2) slab transmission surface, (3) ½ dose at sphere centre.
Dose from solar protons (rads).
Dose from trapped protons (rads).
Dose from trapped electrons (rads).
Dose from Bremsstrahlung (rads).
Total absorbed dose (rads).
A recommended shielding thickness array with
IMAX = 70 covering 1×10⁻⁶ to 50 g/cm² is provided in the IRBEM Fortran source. See the data Zin block in the SHIELDOSE2 Fortran comments.