[P-PS04] Advancing the science of Venus in the golden age of exploration

[PPS04-P11] Correlation analysis of Venus mesoscale UV features between 283 nm SO₂ and 365 nm unknown absorber bands

★Invited Papers

*Masataka Imai¹, Gota Kajita¹, Hiroki Ando¹, Masahiro Takagi¹ (1.Kyoto Sangyo University)

Keywords:Venus, Akatsuki, UVI, Mesoscale features

Venus shows various mesoscale features due to the absorption of solar ultraviolet (UV) radiation at the cloud-top altitude (~65 km). The Ultraviolet Imager (UVI) onboard Venus Climate Orbiter Akatsuki is equipped with two filters of 283 nm and 365 nm to visualize the spatial distribution of SO₂ and unknown absorber (UA), respectively. Previous studies indicated that the UV features have a high positive correlation between the two wavelengths, suggesting SO₂ and UA are closely related in the chemical cycle [Narita et al., 2022]. Therefore, it is expected that SO₂ and UA are similarly affected by atmospheric motions (transport by background winds and waves). However, some observations show that the spatial structure of features differs significantly between these two wavelengths. The cause of the variation in the correlation of the features will be useful for understanding the motion and vertical distribution of materials in the Venusian atmosphere. In this study, we calculated the correlation coefficients between mesoscale features (~ 1000–2000 km) observed at the two wavelengths by UVI and investigated the dependence of the correlation coefficients on local time (LT) and latitude. As a result, the correlation coefficients in the analyzable range of LT = 8 – 16 hr were 0.7 – 0.8 as already reported, showing no significant LT dependence. On the other hand, the correlation coefficients depend on latitude and tend to be small or negative at low latitudes (15^oS – 15^oN). In this presentation, we also discuss the possibility that this latitudinal dependence could be caused by the planetary-scale Kelvin and Rossby waves in the equatorial region.