Delving deeper into Venus&#8217; South Polar Vortex&#8217;s dynamics with VIRTIS-VEx observations
Authors: Garate-Lopez Itziar , Rodriguez-Ovalle Pablo , Fernandez-Urrutia Paula 
Published: September 2022

&lt;p&gt;One of Venus&amp;#8217; 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&amp;#8217;s potential vorticity to try to clarify these points.&lt;/p&gt;
&lt;p&gt;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 &amp;#8211; 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.&lt;/p&gt;
&lt;p&gt;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.&lt;/p&gt;
&lt;p&gt;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.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;[1] I. Garate-Lopez, R. Hueso, A. S&amp;#225;nchez-Lavega, J. Peralta, G. Piccioni, P. Drossart. &lt;em&gt;A chaotic long-lived vortex in Venus&amp;#8217; southern pole&lt;/em&gt;. Nature Geoscience 6, 254-257 (2013). https://doi.org/10.1038/ngeo1764&lt;/p&gt;
&lt;p&gt;[2] I. Garate-Lopez, A. Garc&amp;#237;a Mu&amp;#241;oz, R. Hueso, A. S&amp;#225;nchez-Lavega. &lt;em&gt;Instantaneous three-dimensional thermal structure of the South Polar Vortex of Venus&lt;/em&gt;. Icarus 245, 16-31 (2015). https://doi.org/10.1016/j.icarus.2014.09.030&lt;/p&gt;
&lt;p&gt;[3] I. Garate-Lopez, R. Hueso, A. S&amp;#225;nchez-Lavega, A. Garc&amp;#237;a Mu&amp;#241;oz. &lt;em&gt;Potential Vorticity of the South Polar Vortex of Venus&lt;/em&gt;. Journal of Geophysical Research: Planets 121, 574-593 (2016). https://doi.org/10.1002/2015JE004885&lt;/p&gt;
&lt;p&gt;[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). &lt;em&gt;Retrieval of air temperature profiles in the venusian mesosphere from VIRTIS-M data: Description and validation of algorithms&lt;/em&gt;. Journal of Geophysical Research: Planets 113, 1&amp;#8211;12. https://doi.org/10.1029/2008JE003075&lt;/p&gt;