A Long-lived Sharp Disruption on the Lower Clouds of Venus

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${}^{\circ }$N--40${}^{\circ }$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 $\sim$4.9 days faster than winds at this level ($\sim$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.

21 pages, 10 figures, 2 animated figures and 2 tables

References in corpus (6)

• Latitudinal Variation of Clouds' Structure Responsible for Venus' Cold Collar
• Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki
• New cloud morphologies discovered on the Venus's night during Akatsuki
• Venus cloud morphology and motions from ground-based images at the time of the Akatsuki orbit insertion
• Morphology and dynamics of Venus's middle clouds with Akatsuki/IR1
• Validation of the IPSL Venus GCM Thermal Structure with Venus Express Data

Cited by in corpus (2)

• The Venus' Cloud Discontinuity in 2022
• Amateur Observers Witness the Return of Venus' Cloud Discontinuity