[P-PS05] Recent advances in the science of Venus

[PPS05-06] Variability of Venusian cloud-top winds on the order of a hundred Earth days

★Invited Papers

*Takeshi Horinouchi¹, Toru Kouyama³, Takehiko Satoh², Atsushi Yamazaki² (1.Faculty of Environmental Earth Science, Hokkaido University, 2.ISAS, 3.AIST)

Keywords:Venus, Superrotation, Long-term variability

Winds around the cloud top of Venusian atmosphere has long been observed by tracking cloud features in the ultraviolet images taken by spacecrafts such as Pioneer Venus Orbiter, Venus Express (VEx), and Akatsuki. Studies with VEx suggested that the cloud-top mean zonal winds vary periodically at the periods around two-hundred days [1,2], but a doubt on its reality was raised because of observational limitations [2]. Recent study of winds obtained by using Akatsuki/UVI rather revealed a broad red-noise like frequency spectrum over periods shorter than several hundred days [3]. In this study, we revisit this problem by using both the Akatsuki and VEx winds.

[1] Kouyama et al 2013 https://doi.org/10.1029/2011je004013
[2] Khatuntsev et al 2013 https://doi.org/10.1016/j.icarus.2013.05.018
[3] Horinouchi et al 2024 https://doi.org/10.1029/2023JE008221