Post-Processing & Analysis

After running a simulation, AURORA provides several post-processing functions that compute derived physical quantities from the raw electron flux output. Each reads simulation_data.nc and writes its result as a NetCDF file into the analysis/ subdirectory of the simulation's save directory — see Output & data for the file layout and schema.

This page provides a small description of each analysis function.

Excitation rates

Volume excitation rates

make_volume_excitation_file reads the electron flux from simulation_data.nc, sums over pitch-angle beams to get the omnidirectional flux, and computes the volume excitation rate $Q = I_e \times \sigma \times n$ for several optical emissions (4278 Å, 6730 Å, 7774 Å, 8446 Å, O¹D, O¹S) and ionizations (O⁺, O₂⁺, N₂⁺). Results are saved as analysis/volume_excitation.nc.

make_volume_excitation_file(sim)

Column-integrated excitation rates

make_column_excitation_file integrates the volume excitation rates in altitude, taking into account the finite speed of light (photon travel time from emission altitude to the bottom of the column). This must be run after make_volume_excitation_file. Results are saved as analysis/column_excitation.nc.

make_column_excitation_file(sim)

Top-of-model flux

make_Ie_top_file extracts the electron flux at the top of the ionosphere (maximum simulation altitude), for each pitch-angle beam. This contains all beams, including the upward (backscattered) flux, so it differs from the Ie_input boundary condition stored in simulation_data.nc. It is useful for comparing with satellite or rocket observations. Results are saved as analysis/Ie_top.nc (load with load_Ie_top).

make_Ie_top_file(sim)

Field-aligned currents

make_current_file computes the field-aligned electron current density $J$ (A/m²) and electron energy flux (eV/m²/s), separated into upward and downward components. Results are saved as analysis/currents.nc.

make_current_file(sim)

Heating rates

make_heating_rate_file computes the rate at which energy is transferred from superthermal (energetic) electrons to thermal electrons through Coulomb collisions. Results are saved as analysis/heating_rate.nc.

make_heating_rate_file(sim)

Phase-space density

make_psd_file converts the electron flux into phase-space density. It can compute:

• the full distribution f(z, μ, t, E) (:f_only),
• the reduced parallel distribution F(z, t, v∥) (:F_only), or
• both (:both).

Results are saved as analysis/psd.nc.

make_psd_file(sim; compute = :both)

You can also pass custom v_parallel bin edges:

make_psd_file(sim; compute = :F_only, vpar_edges = range(-2e7, 2e7; length = 100))