MARFA: an Effective Line-by-line Tool For Calculating Molecular Absorption in Planetary Atmospheres

Abstract

We present MARFA (Molecular atmospheric Absorption with Rapid and Flexible Analysis) -- an open-source line-by-line tool for calculating absorption coefficients and cross-sections in planetary atmospheres, particularly under conditions of uncertain spectroscopic data and missing continuum functions. With incorporated eleven-grid interpolation technique MARFA shows good performance in computation of far-wing contributions for large line cut-offs. The tool supports flexible parameterization, including line shape functions, wing corrections, user-defined atmospheric profiles, thus, facilitating rapid sensitivity studies for sparse datasets. Spectra are calculated at a high-resolution of about 5e-4 cm^{-1}, optimized for infrared and visible spectral regions where HITRAN-formatted line data is available, yet adaptable to other datasets with available line parameters. Output is represented either in a form of binary lookup tables files, directly compatible with radiative transfer codes or in a human-readable format for data analysis and distribution. The MARFA tool is provided in two ways: through a web application accessible at marfa.app for onboarding and educational usage, and as an open-source code available in a public repository for advanced utilization, development and contributions.