Characterising Atmospheric Gravity Waves on Mars - a systematic study
Authors: Brasil Francisco , Machado Pedro , Gilli Gabriella , Cardesín-Moinelo Alejandro , Eduardo Silva José , Espadinha Daniela , Rianço-Silva Rafael , Rodrigues Francisco , Gondet Brigitte 
Published: March 2022

&lt;p&gt;Atmospheric gravity waves are mesoscale atmospheric oscillations in which buoyance acts as the restoring force, 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 [1]. &amp;#160;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 [2], however their characteristics are still not well constrained by observations.&lt;/p&gt;&lt;p&gt;We present here follow-up results [3] on the detection and characterization of atmospheric gravity waves on Mars using data from the OMEGA (Observatoire pour la Min&amp;#233;ralogie, l'Eau, les Glaces et l'Activit&amp;#233;) [4] imaging spectrometer onboard the European Mars Express (MEx) space mission [5]. We used image navigation and processing techniques based on contrast enhancement and geometrical projections to characterize morphological properties of the detected waves.&lt;/p&gt;&lt;p&gt;Our observations include 11 months&amp;#8217; worth of data from the first nominal mission of Mars Express, from January 2004 to November 2004. 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. We characterised almost 100 wave-packets across more than 1300 images over a broad region of Mars&amp;#8217; globe and our results show a wide range of properties specially in the evolution of gravity waves along the time, due to the time sampling and global coverage of MEx.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgments&lt;/strong&gt;: This work is supported by Funda&amp;#231;&amp;#227;o para a Ci&amp;#234;ncia e a Tecnologia (FCT)/MCTES through the research grants UIDB/04434/2020, UIDP/04434/2020, and through a grant of reference 2021.05455.BD.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;[1] Fritts, D. C.; Alexander, M. J. Gravity wave dynamics and effects in the middle atmosphere.&amp;#160;&lt;em&gt;Reviews of geophysics&lt;/em&gt;, 2003, 41.1.&lt;/p&gt;&lt;p&gt;[2] Gilli, G., et al. Impact of gravity waves on the middle atmosphere of Mars: A non&amp;#8208;orographic gravity wave parameterization based on global climate modeling and MCS observations.&amp;#160;&lt;em&gt;Journal of Geophysical Research: Planets&lt;/em&gt;, 2020, 125.3: e2018JE005873.&lt;/p&gt;&lt;p&gt;[3] Brasil, Francisco, et al. Characterising Atmospheric Gravity Waves on Mars using Mars Express OMEGA images&amp;#8211;a preliminary study. In:&amp;#160;&lt;em&gt;European Planetary Science Congress&lt;/em&gt;. 2021. p. EPSC2021-188.&lt;/p&gt;&lt;p&gt;[4] Bibring, J. P., et al. OMEGA: Observatoire pour la Min&amp;#233;ralogie, l'Eau, les Glaces et l'Activit&amp;#233;. In: &lt;em&gt;Mars Express: the scientific payload&lt;/em&gt;. 2004. p. 37-49.&lt;/p&gt;&lt;p&gt;[5] Chicarro, A.; Martin, P.; Trautner, R. The Mars Express mission: an overview. In:&amp;#160;&lt;em&gt;Mars Express: The Scientific Payload&lt;/em&gt;. 2004. p. 3-13.&lt;/p&gt;