`absorption` block (optional)

Gas absorption configuration: which molecules are active, where to load HITRAN line data from, broadening / line-shape choices, and the volume mixing ratios (VMRs) per molecule. Skip this block entirely for clear-sky / Rayleigh-only / canopy-only runs.

Required when present

vmr — Dict{String, Union{Real, Vector{Real}}}. Volume mixing ratios per molecule, on the same vertical grid as atmospheric_profile.T. Scalar = uniform VMR; vector = profile. Example: { O2: 0.21, H2O: [1e-6, 1e-5, 1e-4, 1e-3] }.
broadening — String. Line shape function. One of "Voigt()", "Doppler()", "Lorentz()". Voigt is correct across the troposphere and stratosphere; Doppler/Lorentz are diagnostic modes for the high-altitude / surface limits respectively.
CEF — String. Complex error function for Voigt evaluation. One of "HumlicekWeidemann32SDErrorFunction()". Speed/accuracy trade-off rarely worth touching.
wing_cutoff — Integer. Absorption-line wing cutoff in cm⁻¹ (typically 25). Lines outside this distance from each spectral point are skipped.

Molecule-list fields (one of)

fixed_molecules — Vector{Vector{String}}, one inner list per spec_band. Molecules whose VMR is not a state variable in the linearization. Preferred form.
variable_molecules — Vector{Vector{String}}, one inner list per spec_band. Molecules whose VMR is a state variable (Jacobians computed via the analytic lin_* path).
molecules — legacy. Single molecule list applied to all bands; treated as fully-fixed. Don't combine with variable_molecules in new configs.

H₂O is auto-handled when q is set in the profile — don't list it manually.

HITRAN edition

Set the HITRAN edition once per session via:

julia

using vSmartMOM
vSmartMOM.set_hitran_edition!(2020)   # default; or 2016

This is a per-session preference, not a YAML field. The Artifacts infrastructure caches HITRAN snapshots in ~/.julia/scratchspaces/ and downloads on-demand from hitran.org if needed. See the HITRAN Data Management page for the dispatch flow and edition-selection workflow.

Examples

Single-band O₂ A-band retrieval

yaml

absorption:
  vmr:
    O2: 0.21
    N2: 0.78
    Ar: 0.009
  variable_molecules:
    - ["O2"]                # one inner list per spec_band
  fixed_molecules:
    - ["N2", "Ar"]
  broadening: "Voigt()"
  CEF: "HumlicekWeidemann32SDErrorFunction()"
  wing_cutoff: 25

Multi-band with H₂O profile

yaml

atmospheric_profile:
  T: [220.0, 250.0, 280.0]
  p: [0.1, 100.0, 500.0, 1013.25]
  q: [1e-6, 1e-3, 5e-3]      # H₂O auto-included as variable
  profile_reduction: nothing

absorption:
  vmr:
    O2:  0.21
    N2:  0.78
    CO2: 4.0e-4
  variable_molecules:
    - ["O2"]
    - ["CO2"]
  fixed_molecules:
    - ["N2"]
    - ["N2", "O2"]            # cross-band different fixed sets allowed
  broadening: "Voigt()"
  CEF: "HumlicekWeidemann32SDErrorFunction()"
  wing_cutoff: 25

absorption block (optional) ​

Required when present ​

Molecule-list fields (one of) ​

HITRAN edition ​

Examples ​

Single-band O₂ A-band retrieval ​

Multi-band with H₂O profile ​

See also ​