AtmosphericAbsorption.jl

Clean-slate, GPU-accelerated molecular absorption cross-sections for atmospheric radiative transfer — a standalone successor to vSmartMOM's Absorption module.

Goals

• Pluggable line-list sources behind one interface: HITRAN, ExoMol, … (the "Port" hierarchy).
• Advanced line shapes: Voigt → speed-dependent Voigt → Hartmann-Tran, plus line mixing.
• Water-vapor continuum (MT_CKD) and CIA.
• One KernelAbstractions compute core running on CPU, CUDA, and Metal.
• Type-stable and correct in both Float32 and Float64 to machine precision.
• Validated against hapi2 as a golden-file benchmark.

Status

Early development, built in phases:

• Phase 0 ✓ — line-shape math + core abstractions: Architectures, Constants (TOML-defined), LineShapes (complex probability function + Doppler/Lorentz/Voigt), PartitionFunctions.
• Phase 1 ✓ — HITRAN Voigt parity + GPU: columnar LineDatabase, the Port interface, the HitranPort (.par parser + TIPS-2017), the unified KernelAbstractions compute core, and CUDA/Metal extensions. Validated to <5×10⁻³ of HAPI on real CO2/H2O; ~10× faster than HAPI on CPU and ~1900× on an A100 GPU (see benchmark/).
• Phase 2 — advanced shapes (HT/SDV); Phase 3 — ExoMol; Phase 4 — line mixing + continuum; Phase 5 — vSmartMOM integration.

HITRAN API key (for non-Voigt parameters)

Standard HITRAN line data and ExoMol downloads need no credentials. Fetching HITRAN non-Voigt parameters (Hartmann-Tran / speed-dependent / line-mixing) uses the authenticated HITRANonline API and requires your own key from your profile at https://hitran.org. Supply it in-memory (never stored on disk or in this repo):

activate_hitran!("your-key")          # or set the HITRAN_API_KEY environment variable

Develop

julia --project=. -e 'using Pkg; Pkg.test()'