A Long‐Lived Sharp Disruption on the Lower Clouds of Venus
Javier Peralta, T. Navarro, Choon Wei Vun, A. Sánchez‐Lavega, Kevin McGouldrick, Takeshi Horinouchi, Takeshi Imamura, R. Hueso, John P. Boyd, G. Schubert, Toru Kouyama, Takehiko Satoh, N. Iwagami, E. F. Young, M. A. Bullock, Pedro Machado, Yeon Joo Lee, S. S. Limaye, Masato Nakamura, S. Tellmann, A. Wesley, P. F. Miles
Abstract
Abstract Planetary‐scale waves are thought to play a role in powering the yet unexplained atmospheric superrotation of Venus. Puzzlingly, while Kelvin, Rossby, and stationary waves manifest at the upper clouds (65–70 km), no planetary‐scale waves or stationary patterns have been reported in the intervening level of the lower clouds (48–55 km), although the latter are probably Lee waves. Using observations by the Akatsuki orbiter and ground‐based telescopes, we show that the lower clouds follow a regular cycle punctuated between 30°N and 40°S by a sharp discontinuity or disruption with potential implications to Venus's general circulation and thermal structure. This disruption exhibits a westward rotation period of ∼4.9 days faster than winds at this level (∼6‐day period), alters clouds' properties and aerosols, and remains coherent during weeks. Past observations reveal its recurrent nature since at least 1983, and numerical simulations show that a nonlinear Kelvin wave reproduces many of its properties.