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Sources (v0.6 source-term refactor) ​

The radiative-transfer source term — what drives the affine RHS of the MOM operator equation. v0.6 introduced an AbstractSource hierarchy so multiple sources (solar + SIF, solar + thermal, etc.) can compose cleanly. v0.7 surfaces the source list through the trait dispatch in component_m_max(...).

Default ​

If no source is configured, model_from_parameters defaults to SolarBeam() — equivalent to the pre-v0.6 fixed-solar-only behavior.

Sources are first-class types under vSmartMOM.CoreRT. The cleanest way to set them is via the sources= kwarg on model_from_parameters or rt_run:

julia
using vSmartMOM, vSmartMOM.CoreRT

# Solar-only (default)
model = model_from_parameters(params)

# Solar + surface SIF
model = model_from_parameters(params; sources = SolarBeam() + SurfaceSIF())

# Per-call override
R, T = rt_run(model; sources = BlackbodySource(temperature=300.0,
                                                spec_band=1))

YAML configuration ​

A YAML-side sources: list is forthcoming (Phase 7-ish, not shipping in v0.7). For now, configure sources programmatically after parameters_from_yaml. The reason is that some source types (e.g. BlackbodySource) need a model-resolved spectral band that doesn't exist until after model_from_parameters runs.

Source vocabulary ​

TypePurposecomponent_m_max(::T, ctx)
SolarBeam(; F₀=nothing, sza=nothing)Direct solar beam at the model's sza (or obs_geom.sza if not overridden). F₀ is the per-spectral-point Stokes-vector solar irradiance (default Stokes-I unit if not set).0 (neutral — doesn't pin the loop)
SurfaceSIF(; SIF₀=nothing)Sun-induced fluorescence at the lower boundary. Adds isotropically to j₀⁻[:, 1, :].0 (m=0 only)
BlackbodySource(temperature, spec_band; factor=π)Boundary/surface Planck emission at T. The factor=π default makes its F₀ directly comparable to a unit SolarBeam(F₀=1).0 (isotropic)
NoSource()Identity / no-op source. Use as an explicit "I disabled the source" marker.0
SourceSet((s₁, s₂, ...))Tuple-typed composition. Built by s₁ + s₂ operator.maximum(component_m_max.(sources, Ref(ctx)))
ThermalEmissionType stub only in v0.6, not yet wired. The atmospheric volume Planck integral. Reserved name.—
DiffuseBoundaryType stub only. Reserved for diffuse top-of-atmosphere or surface boundary sources.—

SolarBeam → 0 is intentional — the trait aggregator takes a max over components, so 0 is "neutral, let surfaces/scatterers drive". An earlier draft used typemax(Int) and would have pinned every run to user_l_cap; that was a Codex-flagged bug fixed before Phase C landed.

Source-unit convention (v0.6) ​

All source intensities are in mW · m⁻² · cm⁻¹. rt_run output (reflectance / transmittance) is in mW · m⁻² · sr⁻¹ · cm⁻¹. BlackbodySource defaults factor=π so a unit Planck source is comparable to SolarBeam(F₀=1).

Composability ​

julia
src1 = SolarBeam()
src2 = SurfaceSIF()
src3 = BlackbodySource(temperature=300.0, spec_band=1)

# `+` flattens; no nested SourceSet
combined = src1 + src2 + src3   # SourceSet((src1, src2, src3))

# NoSource is identity
combined + NoSource() == combined   # true

# Iteration order is deterministic (a Tuple, not a Set)
for s in combined.sources
    println(typeof(s).name.name)
end

SourceSet is materialized to a concrete Tuple at model_from_parameters time so the hot RT loop sees a fully type-stable iterable.

See also ​