Gravity waves in the upper atmosphere of Venus revealed by CO 2 nonlocal thermodynamic equilibrium emissions

• Published in: Journal of Geophysical Research
• Main Authors: Garcia, R. F., Drossart, P., Piccioni, G., López-Valverde, M., Occhipinti, G.
• Other Authors: Services communs OMP (UMS 831), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: [SDU]Sciences of the Universe [physics]; South Pole; Venus; South pole
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03604910; https://hal-insu.archives-ouvertes.fr/insu-03604910/document; https://hal-insu.archives-ouvertes.fr/insu-03604910/file/Journal%20of%20Geophysical%20Research%20Planets%20-%202009%20-%20Garcia%20-%20Gravity%20waves%20in%20the%20upper%20atmosphere%20of%20Venus%20revealed%20by%20CO2.pdf; https://doi.org/10.1029/2008JE003073

International audience The imaging capabilities of the Visible and Infrared Thermal Imaging Spectrometer-Mapper (VIRTIS-M) onboard Venus Express mission are used to analyze perturbations of CO 2 nonlocal thermodynamic equilibrium emissions in the thermosphere of Venus. These emissions with a wavelength of 4.3 μm originate from the 110-140 km altitude range and are sensitive to density perturbations. They show wave-like perturbations of about 0.5% root-mean-square amplitude of the background signal with horizontal wavelengths in the 90-400 km range. The horizontal phase velocities are similar in magnitude and direction from one orbit to the next, with averages of 70 m/s westward and 30 m/s northward. The geographical wave distribution and the orientation of wavefronts demonstrate that the polar vortex at work in the cloud layer is the source of these gravity waves. The large westward zonal phase velocity in the 0900-1500 local time range argues in favor of the superrotation dynamics within 30° from the south pole to an altitude of at least 115 km. The gravity wave dispersion relation and the geographical distribution of wavefront amplitudes suggest the presence of a solar to antisolar wind close to the south pole. Because the centroid altitude and the sensitivity of these emissions to gravity wave perturbations are only roughly estimated, it is not possible to make a quantitative estimate of the upward energy transfer. However, this study demonstrates the strong influence of the polar vortex on the circulation in the atmosphere of Venus up to the thermosphere.