Europlanet Science Congress 2021
Virtual meeting
13 – 24 September 2021
Europlanet Science Congress 2021
Virtual meeting
13 September – 24 September 2021
EPSC Abstracts
Vol. 15, EPSC2021-188, 2021, updated on 21 Jul 2021
https://doi.org/10.5194/epsc2021-188
European Planetary Science Congress 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Characterising Atmospheric Gravity Waves on Mars using Mars Express OMEGA images – a preliminary study

Francisco Brasil1, Pedro Machado1, Gabriella Gilli1, Alejandro Cardesín-Moinelo2, José E. Silva1, Daniela Espadinha1, and Brigitte Gondet3
Francisco Brasil et al.
  • 1Institute of Astrophysics and Space Sciences, Lisbon, Portugal (fbrasil@oal.ul.pt)
  • 2European Space Astronomy Centre, Spain
  • 3Institut d'Astrophysique Spatiale, (CNRS, Université Paris-Saclay), Orsay, France

We report preliminary result of the systematic detection and characterisation of atmospheric gravity waves on Mars' atmosphere, using observations carried out by the OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) [1] imaging spectrometer on board of the Mars Express (MEx) [2].

Gravity waves are mesoscale atmospheric oscillations in which buoyance acts as the restoring force [3]. The presence of gravity waves is observed in many of the Solar System planets atmospheres, from Venus [4], Earth [5], Jupiter [6], and being a crucial factor in the circulation of planetary atmospheres since they transport momentum and energy, which can dissipate at different altitudes and force the dynamics of several layers of the atmosphere.

The source of these waves can be associated with the topographic features (orographic gravity waves) of surface, or with jet streams and atmospheric convections (non-orographic gravity waves). Recent modelling studies showed the strong role of gravity waves on diurnal tides on Mars atmosphere [7], however their characteristic are still not well constrained by observations.

 This work aims to go through the complete OMEGA data set to fully detect and characterise gravity waves observed during the Mars Express space probe. Every image was navigated and processed in order to optimise the detection of the wave packets and accurate characterisation of the wave properties such as the horizontal wavelength, packet width, packet length and orientation.

Due to the longevity of the MEx space mission, acquiring over more than 17 years of observations of the surface and atmosphere of Mars in nadir and limb modes, the OMEGA instrument offers an opportunity to explore the atmosphere dynamics over the years, especially the evolution of gravity waves along the time, due to the time sampling and global coverage of MEx.

The OMEGA images are composed of a hyperspectral cube with a spectral range of 0.38 to 5.1 m, taken with the visible and near-infrared (VNIR) and infrared (SWIR) spectrometers. We retrieved the OMEGA data and its IDL routines through the PSA archive from ESA, to produce OMEGA images which were later navigated and processed individually using ENVI software for optimal detection of wave features and accurate characterisation of wave properties, such as the horizontal wavelengths, packet width, packet length, location and orientation. Since the orbit has a certain resonance with respect to the Martian surface rotation (variable duration along the mission), there will be an overlapping of images taken, allowing the study of the evolution of gravity waves along a period of time and also the study of their activity during dust storms [8].