Identity of Venus’s ultraviolet cloud absorber

Identify the ultraviolet-absorbing atmospheric constituent responsible for the observed variations in Venusian cloud-top albedo.

Background

The paper attributes changes in cloud-top albedo to an ultraviolet absorber that controls the absorption of incoming solar ultraviolet radiation and thereby influences atmospheric temperatures. Although this absorber is central to interpreting the observed thermal variability, its identity has not been established. Resolving this uncertainty would improve the physical interpretation and parameterization of Venusian climate models.

References

As stated earlier, the characteristic variability in the Venusian atmospheric thermal structure across the years has been linked to the changing cloud-top albedo, which in turn primarily depends on the mysterious, still-unknown UV absorber \citep{Lee_2019, Ando_2025}.

— Study on the Venusian Atmospheric Thermal Structure: A Comparative Analysis between VEX/Akatsuki and Venus-GRAM/VCD  (2608.26768 - Banerjee et al., 27 Aug 2026) in Section 3.3, Investigating the link between the cloud albedo and the cloud top temperatures using VCD