Effective parameterization of absorption by gaseous species and unknown UV absorber in 125-400 nm region of Venus atmosphere

TL;DR

This paper introduces a simplified parameterization method for molecular absorption in Venus's atmosphere within 125-400 nm, enabling faster radiative transfer calculations with high accuracy.

Contribution

It develops an effective parameterization of gaseous absorption and optical properties for Venus's atmosphere, reducing computational complexity in spectral modeling.

Findings

Discrepancy in fluxes less than 3% compared to line-by-line models

Only eight spectral points needed for accurate UV flux and heating rate calculations

Parameterization effectively captures absorption by CO2, SO2, and unknown UV absorber

Abstract

We present an effective parameterization of molecular absorption of shortwave solar radiation in Venus atmosphere. It is addressed to general circulation modeling to accelerate radiative transfer calculations in the spectral interval 125 -- 400 nm (25000 -- 80000 cm$^{-1}$ ). In F-UV and M-UV regions strong absorption of CO$_2$ ans SO$_2$ enables to parameterize gaseous absorption with only three effective cross-sections. In N-UV region absorption of SO$_2$ and the unknown UV absorber are parameterized with six effective cross-sections for each species. For treatment of Rayleigh scattering and optical properties of Venus clouds eight effective spectral points are recommended. Parameterizations were validated by the original reference line-by-line Monte-Carlo radiative transfer model. The outcome of the validation shows the discrepancy in fluxes less than 3%. Thus, it takes only eight-fold solution of radiative transfer equations to correctly describe solar fluxes and heating rates in the whole ultraviolet region.