Planetary‐Scale Waves Seen in Thermal Infrared Images of Venusian Cloud Top
Naoya Kajiwara, Takeshi Imamura, Makoto Taguchi, Toru Kouyama
Abstract
Abstract Planetary‐scale waves are thought to play a crucial role in the maintenance of the atmospheric circulation of Venus. They have been mainly studied using ultraviolet images. In this study, cloud top temperature oscillations associated with planetary‐scale waves were extracted from thermal images taken over 142 Earth days by the Longwave Infrared Camera onboard JAXA's Akatsuki spacecraft. A spectral analysis showed that multiple planetary‐scale waves overlap. The latitudinal structures of four distinct waves with periods of 3.6, 5.0, 5.4, and 6.1 days were studied. The 3.6‐day wave is considered to be a Kelvin wave and the other waves are considered to be hemispherically symmetric Rossby waves. Although the Rossby waves have similar periods, their latitudinal structures are different. The Rossby waves are considered to originate from different sources based on a comparison with analytical solutions.