Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images

Sanjay S. Limaye, Shigeto Watanabe, Atsushi Yamazaki, Manabu Yamada, Takehiko Satoh, Takao M. Sato, Masato Nakamura, Makoto Taguchi, Tetsuya Fukuhara, Takeshi Imamura, Toru Kouyama, Yeon Joo Lee, Takeshi Horinouchi, Javier Peralta, Naomoto Iwagami, Joji Hashimoto, Seiko Takagi, Shoko Ohtsuki, Shin ya Murakami, Yukio YamamotoKazunori Ogohara, Hiroki Ando, Ko ichiro Sugiyama, Nobuaki Ishii, Takumi Abe, Chikako Hirose, Makoto Suzuki, Naru Hirata, Eliot F. Young, Adriana C. Ocampo

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Since insertion into orbit on December 7, 2015, the Akatsuki orbiter has returned global images of Venus from its four imaging cameras at eleven discrete wavelengths from ultraviolet (283 and 365 nm) and near infrared (0.9–2.3 µm), to the thermal infrared (8–12 µm) from a near-equatorial orbit. The Venus Express and Pioneer Venus Orbiter missions have also monitored the planet for long periods but from polar or near-polar orbits. The wavelength coverage and views of the planet also differ for all three missions. In reflected light, the images reveal features seen near the cloud tops (~ 70 km altitude), whereas in the near-infrared images of the nightside, features seen are at mid- to lower cloud levels (~ 48–60 km altitude). The dayside cloud cover imaged at the ultraviolet wavelengths shows morphologies similar to what was observed from Mariner 10, Pioneer Venus, Galileo, Venus Express and MESSENGER. The daytime images at 0.9 and 2.02 µm also reveal some interesting features which bear similarity to the ultraviolet images. The nighttime images at 1.74, 2.26 and 2.32 µm and at 8–12 µm reveal features not seen before and show new details of the nightside including narrow wavy ribbons, curved string-like features, long-scale waves, long dark streaks, isolated bright spots, sharp boundaries and even mesoscale vortices. Some features previously seen such as circum-equatorial belts (CEBs) and occasional areal brightenings at ultraviolet (seen in Venus Express observations) of the cloud cover at ultraviolet wavelengths have not been observed thus far. Evidence for the hemispheric vortex organization of the global circulation can be seen at all wavelengths on the day- and nightsides. Akatsuki images reveal new and puzzling morphology of the complex nightside cloud cover. The cloud morphologies provide some clues to the processes occurring in the atmosphere and are thus, a key diagnostic tool when quantitative dynamical analysis is not feasible due to insufficient information.[Figure not available: see fulltext.].

Original languageEnglish
Article number24
JournalEarth, Planets and Space
Volume70
Issue number1
DOIs
Publication statusPublished - Dec 1 2018

Keywords

  • Day
  • Morphology
  • Near infrared
  • Night
  • Ultraviolet
  • Venus clouds

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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    Limaye, S. S., Watanabe, S., Yamazaki, A., Yamada, M., Satoh, T., Sato, T. M., Nakamura, M., Taguchi, M., Fukuhara, T., Imamura, T., Kouyama, T., Lee, Y. J., Horinouchi, T., Peralta, J., Iwagami, N., Hashimoto, J., Takagi, S., Ohtsuki, S., Murakami, S. Y., ... Ocampo, A. C. (2018). Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images. Earth, Planets and Space, 70(1), [24]. https://doi.org/10.1186/s40623-018-0789-5