Séminaire LATMOS (Amphithéâtre Gérard Mégie, Guyancourt), Jeudi 26 juin 2014, 11h

Orateur: David Luz (Centro de Astronomia e Astrofisica da Universidade de Lisboa, Observatorio Astronomico de Lisboa)

Titre: Venus Polar Vortex Dynamics: measurements from 2.5 years of Venus Express/VIRTIS observations

Résumé: The Venus southern polar vortex is in constant dynamical change. Its morphology exhibits striking daily variability, and its centroid of rotation is displaced from the rotational geometry of the planet and occasionally displays a precessing motion about the pole. But what is the mean state of the vortex on a long-term basis and how does it relate to the atmospheric dynamics at lower latitudes?

ESA's Venus Express has been orbiting Venus since 2006, and the infrared mapping channel of the VIRTIS instrument acquired about 2.5 years of data before its cryocooler eventually malfunctionned, among which many sequences of images of high latitudes in the southern hemisphere.

I will examine the short- and long-term dynamics of the polar vortex, based on measurements of winds obtained by cloud motion monitoring at the 45 and 65-km levels, from the complete VIRTIS-M infrared dataset. I will present the mean zonal winds and vorticity profiles, addressing the stability of the flow and discussing the major structures of the general atmospheric circulation based on new results.