Struct

`space::irbem::OpdConstants`

cheatah-space v0.1.0-alpha — Biome Standard 0.6.5-alpha

The constants of the dynamic model that are not the quiet field's own, each with its source.

Gathered into one constexpr object so that every number in the evaluator has a name, a unit and a citation, and so the two arithmetic lanes read one definition.

Unit testIrbemOpd.TheConstantsAreThePublishedOnes

Constants & variables

var double pressure_npa_per_cc_km2s2 #

m_p in the units that make n [cm^-3] V^2 [km^2 s^-2] come out in nPa: the CODATA 2018 proton mass 1.67262192369e-27 kg times 1e6 m^-3 / cm^-3 times 1e6 m^2 s^-2 / km^2 s^-2 times 1e9 nPa / Pa.

The solar wind is treated as protons, which is what the IRBEM driver table calls "solar wind density".

var double reference_density #

The reference density, cm^-3: the quiet end of the model's documented envelope (5 <= Dsw <= 50, IRBEM general_information.rst), at which the quiet field is uncompressed.

var double reference_velocity #

The reference speed, km/s: the canonical nominal solar wind, in the middle of the documented 300 <= Vsw <= 500.

var double dst_pressure_coefficient #

b in Dst* = Dst - b sqrt(P) + c, nT per sqrt(nPa) — O'Brien & McPherron, JGR 105, 7707 (2000), the pressure correction that removes the magnetopause-current contribution from the index, which is exactly what the model's "modified Dst" is described as.

var double dst_offset #

c in the same relation, nT — the quiet-time offset of the same paper.