A preview of the Venus atmosphere in 3D
2017 May 23

Night side of Venus taken in the infrared by Akatsuki spacecraft (JAXA). Credits: ISAS, JAXAPedro Machado, of Instituto de Astrofísica e Ciências do Espaço. Credits: Pedro Machado.
The first approach to a three-dimensional reconstruction of the atmospheric circulation of Venus is presented in an paper1 published in the Geophysical Research Letters, led by Javier Peralta2 and co-authored by Pedro Machado, of Instituto de Astrofísica e Ciências do Espaço (IA3) and Faculdade de Ciências da Universidade de Lisboa (FCUL).

This study gathers data about wind speed and atmospheric temperature at different heights collected within roughly a month, and independently, by two space missions, MESSENGER, of NASA, and Venus Express, of ESA, and by several instruments on the ground. This is an important input to the future understanding of what caused and sustains the super-rotation4 of the Venus atmosphere.

According to Pedro Machado (IA and FCUL), “this study consists in the first time that data collected at different altitudes in the atmosphere are integrated in order to reconstruct not only the horizontal circulation, but also the vertical displacement of the wind. The idea is to try to understand how the air flux works, both at the same height and how the variation of the wind at a given height affects an atmospheric layer above.

” This first approach to what is going on globally in the atmosphere of Venus is of great relevance. It will be useful in the preparation of future operations, such as those of the Akatsuki (JAXA) mission in which IA collaborates, as well as in the improvement of theoretical models that attempt to simulate the general circulation of planetary atmospheres, and notably that of Venus.

“There is a region in the atmosphere of Venus, above the layer that is in super-rotation, which presents a surprising variability that the global atmospheric circulation models are yet unable to characterise,” says Gabriella Gilli (IA and FCUL), researcher in the team of Pedro Machado. “The measurements of wind speed and temperature described in this paper offer valuable constraints that will support the theoretical models in our understanding of the processes that are going on in this intriguing region.”

One of the next steps following on this paper now published, says Pedro Machado, is to obtain data with higher resolution, observing with greater detail. His team is actively working in this direction, for instance, in the study of the propagation of fluctuations in the air density. This waves carry energy across the atmosphere, and understanding them will be one more input to the attempt to explain the super-rotation of the atmosphere of planet Venus. For this study, now published in the Geophysical Research Letters, Pedro Machado's team provided measurements of the wind speed at the level of cloud tops obtained with the high-resolution spectrograph UVES, located in the Very Large Telescope (ESO).

  1. The scientific paper “Venus's winds and temperatures during the MESSENGER's flyby: An approximation to a three-dimensional instantaneous state of the atmosphere”, by Javier Peralta et al., was published online on April 30, 2017, in the journal Geophysical Research Letters, Volume 44 (DOI: 10.1002/2017GL072900).
  2. Javier Peralta, now researcher at the Japanese Aerospace Exploration Agency-JAXA, is since 2011 a collaborator of the IA research group in Solar System.
  3. The Instituto de Astrofísica e Ciências do Espaço (Institute of Astrophysics and Space Sciences – IA) is the largest Portuguese research unit in space sciences and integrates researchers from the University of Lisbon and the University of Porto. The institute encompasses most of the field’s national scientific output and it was evaluated as Excellent in the last evaluation from the European Science Foundation (ESF). IA’s activity is funded by national and international funds, including Fundação para a Ciência e a Tecnologia (UID/FIS/04434/2013), POPH/FSE and FEDER through COMPETE 2020.
  4. The super-rotation of Venus atmosphere is a phenomenon in which, due to the winds parallel to the equator, or zonal winds, the atmosphere circles the planet in just little more than four Earth days, that is, 60 times faster than the rotation period of the solid globe, which is 243 Earth days. As a consequence, the normal wind speed relative to the surface is about 360 km/h.

Contacts Science Communication Group

Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Fundação para a Ciência e a Tecnologia