Venus Cloud Winds and Mean Albedo Variability From Atmospheric Waves

Abstract

Venus's atmosphere presents an enigmatic global circulation with winds that rotate around the planet 60 times faster than the slow rotation of the surface. For decades the connection between the atmospheric super rotation and atmospheric waves has been suspected. However, the characterization of how these atmospheric waves originate, interact with the global circulation, and dissipate has been difficult. Recent results from the Akatsuki mission (Imai et al., 2019, https://doi.org/10.1029/ 2019JE006065) show explicitly the emergence of planetary-scale Kelvin and Rossby waves at the upper cloud tops and how they transform from one type of wave to other giving new insights in the atmospheric super rotation.Plain Language Summary Venus is a mysterious planet in many aspects. One of them is its global atmospheric circulation. In a planet that rotates so slowly that its year (224.7 Earth days) is only 1.9 times longer than its solar day (116.7 Earth days), the visible clouds rotate around the planet with velocities of ∼360 km/hr, touring the planet in ∼4 Earth days. A crucial element to power these winds is atmospheric waves that transport energy and momentum through the atmosphere. However, a good characterization of the waves and the changes they impose on the winds has been missing from results of Venus exploration collected by a variety of space missions. In a recent analysis of images of the upper clouds of Venus obtained by the Akatsuki mission, Imai et al. (2019, https://doi.org/10.1029/2019JE006065) characterize changes in the winds and albedo of the planet as planetary-scale waves develop, transform from one type into another, and vanish. Their study opens the door to an improved understanding of the role of the planetary-scale waves in shaping Venus superrotating winds.