Abstract
Waves are ubiquitous phenomena found in oceans and atmospheres alike. From the earliest formal studies of waves in the Earth’s atmosphere to more recent studies on other planets, waves have been shown to play a key role in shaping atmospheric bulk structure, dynamics and variability1,2,3,4. Yet, waves are difficult to characterize as they ideally require in situ measurements of atmospheric properties that are difficult to obtain away from Earth. Thus, we have incomplete knowledge of atmospheric waves on planets other than our own, and we are thereby limited in our ability to understand and predict planetary atmospheres. Here we report the first ever in situ observations of atmospheric waves in Venus’s thermosphere (130–140 km) at high latitudes (71.5°–79.0°). These measurements were made by the Venus Express Atmospheric Drag Experiment (VExADE)5 during aerobraking from 24 June to 11 July 2014. As the spacecraft flew through Venus’s atmosphere, deceleration by atmospheric drag was sufficient to obtain from accelerometer readings a total of 18 vertical density profiles. We infer an average temperature of T = 114 ± 23 K and find horizontal wave-like density perturbations and mean temperatures being modulated at a quasi-5-day period.
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Acknowledgements
S.B. and J.-C.M. thank CNES/TOSCA for their support.
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I.C.F.M.-W. carried out the density wave extraction and analysis shown in Figs 2–4, and jointly with S.B. led the scientific interpretation of the results. S.B. and J.-C.M. performed the analysis of raw accelerometer readings using the GINS software to obtain density values. S.B. carried out the error analysis which led to Fig. 1. H.S. led the implementation of the VExADE experiment in the mission planning and made important scientific contributions in the interpretation of the data. I.C.F.M.-W. wrote the paper with significant contributions from all the authors in interpreting the results and editing of the manuscript.
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Müller-Wodarg, I., Bruinsma, S., Marty, JC. et al. In situ observations of waves in Venus’s polar lower thermosphere with Venus Express aerobraking. Nature Phys 12, 767–771 (2016). https://doi.org/10.1038/nphys3733
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DOI: https://doi.org/10.1038/nphys3733
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