How waves and turbulence maintain the super-rotation of Venus' atmosphere

Takeshi Horinouchi; Yoshi-Yuki Hayashi; Shigeto Watanabe; Manabu Yamada; Atsushi Yamazaki; Toru Kouyama; Makoto Taguchi; Tetsuya Fukuhara; Masahiro Takagi; Kazunori Ogohara; Shin-Ya Murakami; Javier Peralta; Sanjay S Limaye; Takeshi Imamura; Masato Nakamura; Takao M Sato; Takehiko Satoh

doi:10.1126/science.aaz4439

How waves and turbulence maintain the super-rotation of Venus' atmosphere

Science. 2020 Apr 24;368(6489):405-409. doi: 10.1126/science.aaz4439.

Authors

Takeshi Horinouchi^{1

2}, Yoshi-Yuki Hayashi³, Shigeto Watanabe⁴, Manabu Yamada⁵, Atsushi Yamazaki², Toru Kouyama⁶, Makoto Taguchi⁷, Tetsuya Fukuhara⁷, Masahiro Takagi⁸, Kazunori Ogohara⁹, Shin-Ya Murakami², Javier Peralta², Sanjay S Limaye¹⁰, Takeshi Imamura¹¹, Masato Nakamura^{2

12}, Takao M Sato⁴, Takehiko Satoh^{2

12}

Affiliations

¹ Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan. horinout@ees.hokudai.ac.jp.
² Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan.
³ Department of Planetology and Center for Planetary Science, Kobe University, Kobe, Japan.
⁴ Space Information Center, Hokkaido Information University, Ebetsu, Japan.
⁵ Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Japan.
⁶ Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan.
⁷ College of Science, Rikkyo University, Tokyo, Japan.
⁸ Faculty of Science, Kyoto Sangyo University, Kyoto, Japan.
⁹ School of Engineering, University of Shiga Prefecture, Hikone, Japan.
¹⁰ Space Science and Engineering Center, University of Wisconsin-Madison, Madison, WI, USA.
¹¹ Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan.
¹² Department of Space and Astronautical Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Tokyo, Japan.

PMID: 32327594
DOI: 10.1126/science.aaz4439

Abstract

Venus has a thick atmosphere that rotates 60 times as fast as the surface, a phenomenon known as super-rotation. We use data obtained from the orbiting Akatsuki spacecraft to investigate how the super-rotation is maintained in the cloud layer, where the rotation speed is highest. A thermally induced latitudinal-vertical circulation acts to homogenize the distribution of the angular momentum around the rotational axis. Maintaining the super-rotation requires this to be counteracted by atmospheric waves and turbulence. Among those effects, thermal tides transport the angular momentum, which maintains the rotation peak, near the cloud top at low latitudes. Other planetary-scale waves and large-scale turbulence act in the opposite direction. We suggest that hydrodynamic instabilities adjust the angular-momentum distribution at mid-latitudes.

Publication types

Research Support, Non-U.S. Gov't