JpGU-AGU Joint Meeting 2017

Presentation information

[EJ] Poster

P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS06] [EJ] Results of Venus science with Akatsuki in orbit for 1.5 year

Sat. May 20, 2017 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL7)

[PPS06-P06] Stationary waves and slow cloud features challenge Venus's night side superrotation

*Javier Peralta1, Ricardo Hueso2, Agustín Sánchez-Lavega2, Yeon Joo Lee1, Antonio García-Muñoz3, Toru Kouyama4, Hideo Sagawa5, Takao Sato1, Giuseppe Piccioni6, Takeshi Imamura7, Takehiko Satoh1 (1.Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), JAPAN, 2.Universidad del País Vasco (UPV/EHU), Bilbao, SPAIN, 3.Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, GERMANY, 4.Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology, JAPAN, 5.Faculty of Science, Kyoto Sangyo University, JAPAN, 6.Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), ITALY, 7.Graduate School of Frontier Sciences, University of Tokyo, JAPAN)

Keywords:Venus, Atmosphere, Atmospheric Dynamics, Atmospheric Waves

The atmosphere of Venus rotates with velocities that at the cloud tops (65-70 km above surface) can be sixty times faster than the underlying surface, a phenomenon known as superrotation that continues to puzzle atmospheric scientists after decades of research. Whereas on Venus's dayside the cloud top motions are well determined, the night side circulation remains poorly studied except for the polar region. Here, we report first global measurements of the night side circulation of Venus at the upper cloud level from the tracking of individual features in thermal emission images at 3.8 and 5.0 microns during 2006-2008 (Venus Express/VIRTIS) and 2015 (IRTF/SpeX). Contrarily to the dayside motions dominated by mean super-rotating winds ranging -120 to -90 m/s at this altitude, night side motions are far more variable, revealing well-contrasted features moving at similar velocities than the day side features, stationary wave patterns with zonal speeds ranging from -10 to +10 m/s and a complex mixture of cloud-like features with apparent motions ranging from -80 to -40 m/s. These results defy the paradigm of an ubiquitous steady day and night stable superrotation at this altitude level and decades of numerical efforts to explain Venus's General Circulation.