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RT1D O-Mode Appleton Absorption (IRI)

1D O-Mode Absorption Curves in dB/km

Uses a 1D IRI profile with NRLMSISE-driven collision frequency and computes Appleton-Hartree O-mode absorption for three frequencies (default includes 30 MHz).

This page explains:

  • examples/rtmodel_omode_absorption_appleton_iri_1d.py

Call Flow

  1. Load config1D.json via load_config_1D(...).
  2. Build profile:
  3. RT1DProfile.from_cfg(..., fetch_iri=True, fetch_msise=True, fetch_geomag=True)
  4. Build collision profile from NRLMSISE neutrals through:
  5. ComputeCollision.from_nrlmsise(...)
  6. For each requested frequency, evaluate:
  7. AppletonHartreeDispersion(...).evaluate(mode="O")
  8. Plot a two-panel figure:
  9. left: absorption vs altitude in dB/km
  10. right: plasma frequency (f_p) and collision frequency (nu) in MHz

Key Code

1) Build 1D Profile

profile = RT1DProfile.from_cfg(
    cfg=cfg,
    time=event_time,
    fetch_iri=True,
    fetch_msise=True,
    fetch_geomag=True,
)

2) Build Collision and Evaluate Appleton O-Mode

cc = ComputeCollision.from_nrlmsise(
    date=event_time,
    alts_km=profile.alts_km,
    Te=profile.Te,
    Ti=profile.Ti,
    edens=profile.ne_cm3,
    O2p=profile.O2p,
    Op=profile.Op,
)

disp = AppletonHartreeDispersion(
    frequency_hz=freq_hz,
    ne_m3=profile.ne_m3,
    collision_hz=cc.collision.nu_ft,
    b_t=profile.b_abs_t,
    theta_deg=profile.b_psi_deg,
)
res = disp.evaluate(mode="O")

3) Plot Construction

# left panel: absorption(dB/km) vs altitude
# right panel: fp(MHz) and nu(MHz) diagnostics
fig.savefig(out_file, dpi=300, bbox_inches="tight")

Run

cd /home/chakras4/Research/CodeBase/trace
python examples/rtmodel_omode_absorption_appleton_iri_1d.py

Custom frequencies (must be 3 values):

python examples/rtmodel_omode_absorption_appleton_iri_1d.py --freqs 15,22,30

Disable automatic collision-frequency safety rescale:

python examples/rtmodel_omode_absorption_appleton_iri_1d.py --no-auto-nu-rescale

Output Figure

Default output:

  • docs/examples/figures/rt1d_omode_absorption_appleton_iri.png

RT1D O-mode absorption

  • examples/rtmodel_omode_absorption_appleton_iri_1d.py
  • hfpytrace/model/rt1d.py
  • hfpytrace/model/dispersion.py
  • hfpytrace/collision.py
  • hfpytrace/plottrace.py

See Also