Delving deeper into Venus’ South Polar Vortex’s dynamics with VIRTIS-VEx observations
- 1Dpto. Física Aplicada, Escuela de Ingeniería de Bilbao, UPV/EHU, Bilbao, Spain
- 2LESIA, Université Paris Cité, Observatoire de Paris, Université PSL, Sorbonne Université, CNRS, F-92190 MEUDON, France
One of Venus’ unsolved mysteries is the dynamics of its polar vortices: what makes them so changeable? Where do they get the energy to survive for at least 8 years without disappearing once? How, if at all, do they affect the general circulation of the atmosphere (the so-called superrotation)? Here, we will show new measurements of wind, air temperature, and Ertel’s potential vorticity to try to clarify these points.
The VIRTIS imaging spectrometer on board the Venus Express spacecraft constantly observed the south polar vortex from 2006 to 2014. Using the data provided by this instrument in the 1.0 – 5.1 microns wavelength range, we have analysed 11 different dates and morphologies of the vortex, which added to those analysed in our previous studies [1, 2, 3] sum up to 35 in total for the wind analysis, 8 for the thermal analysis and 8 for the potential vorticity analysis.
Wind speed has been measured by tracking clouds in more than a couple of images per date. Radiative transport and inversion techniques have been used to obtain the three-dimensional spatial distribution of the air temperature [4]. In this way, we have produced wind maps at two heights (for the lower cloud and the upper cloud, that is, ~42 km and ~62 km above the surface at polar latitudes) and air temperature maps for several atmospheric layers between 55 and 85 km altitude.
The aim is to improve our understanding of the dynamics governing these vortices by confirming or refuting previously observed trends [3]. For example, the annular shape of the potential vorticity in the upper level of the clouds or the anti-correlation between the visible structures in the thermal infrared (the most characteristic structures of the Venus polar vortex) and the peaks of the potential vorticity.
References
[1] I. Garate-Lopez, R. Hueso, A. Sánchez-Lavega, J. Peralta, G. Piccioni, P. Drossart. A chaotic long-lived vortex in Venus’ southern pole. Nature Geoscience 6, 254-257 (2013). https://doi.org/10.1038/ngeo1764
[2] I. Garate-Lopez, A. García Muñoz, R. Hueso, A. Sánchez-Lavega. Instantaneous three-dimensional thermal structure of the South Polar Vortex of Venus. Icarus 245, 16-31 (2015). https://doi.org/10.1016/j.icarus.2014.09.030
[3] I. Garate-Lopez, R. Hueso, A. Sánchez-Lavega, A. García Muñoz. Potential Vorticity of the South Polar Vortex of Venus. Journal of Geophysical Research: Planets 121, 574-593 (2016). https://doi.org/10.1002/2015JE004885
[4] D. Grassi, P. Drossart, G. Piccioni, N. I. Ignatiev, L. V. Zasova, A. Adriani, M. L. Moriconi, P. G. J. Irwin, A. Negrao, A. Migliorini (2008). Retrieval of air temperature profiles in the venusian mesosphere from VIRTIS-M data: Description and validation of algorithms. Journal of Geophysical Research: Planets 113, 1–12. https://doi.org/10.1029/2008JE003075
How to cite: Garate-Lopez, I., Rodriguez-Ovalle, P., and Fernandez-Urrutia, P.: Delving deeper into Venus’ South Polar Vortex’s dynamics with VIRTIS-VEx observations, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-387, https://doi.org/10.5194/epsc2022-387, 2022.
