Wave Packets at Venus’s Cloud Tops as Seen by Akatsuki

Abstract We present a survey of atmospheric waves in the upper cloud layer of Venus based on UV imagery acquired by the Akatsuki spacecraft’s Ultraviolet Imager with the 365 nm filter. Using processing techniques based on contrast enhancement and geometrical projections to detect and analyze wave packets, we retrieved their morphological properties, including horizontal wavelength, packet width, length, and orientation, as well as dynamical properties such as intrinsic phase speed and vertical wavelength. These results were compared with independent measurements from thermal profile analysis from Akatsuki radio occultation data and earlier data sets from Venus Express (Venus Monitoring Camera and VIRTIS-M). These waves share numerous similarities with the so-called bow waves observed by Mariner 10 and Pioneer Venus, with packets concentrated at low latitude and from late morning to early evening hours (11–16 hr) and with overall large morphologies (up to 4500 km of length and around 2500 km of width). This study provides the first detailed characterization of bow waves at Venus’s cloud tops to support future research on their potential role in shaping the planet’s general atmospheric circulation.