Past Seminars Seminários Já Decorridos 2009

Characterizing the atmosphere of Venus with Venus Express

By: David Luz
From: Centro de Astronomia e Astrofisica da Universidade de Lisboa, Observatorio Astronomico de Lisboa
At: Complexo Interdisciplinar, Anfiteatro
[2009-03-04] 11:00

Planet Venus is the Earth twin, and one of the most challenging bodies in the Solar System. The 90 bar pressure and 740 K temperature at the surface make its atmosphere the densest and hottest of the terrestrial-type atmospheres. Having started with conditions very similar to the Earth, some say it holds clues as to the origin, behaviour and evolution of our own atmosphere. The European Space Agency mission Venus Express has been orbiting Venus since 2006, and has provided fresh data at unprecedented spatial and temporal resolution. It has given new insights into its complex atmospheric dynamics, composition and evolution, by measuring winds, airglow processes and atmospheric escape. Turbulence and wave phenomena are also being investigated, allowing to establish the type of meteorology that characterizes the venusian atmosphere. In addition, general circulation models are being developed to help interpret these measurements and to understand the couplings between the different atmospheric processes. Superrotation is a surprising, but well known, feature of the atmosphere of Venus, where the cloud tops rotate 60 times faster than the surface of the solid globe. A good characterization of the circulation of the atmosphere is essential to understand the mechanisms controlling superrotation. VIRTIS, onboard Venus Express, is one of the most flexible instruments for that purpose. It consists of an imaging spectrometer, operating in the range 0.25 to 5 micrometers, which is mapping the planet cloud layer from the cloud tops at 70 km altitude to the lower cloud layer at 40 km. The seminar will present a general view of the venusian atmosphere, based on some of the new discoveries of Venus Express, such as the southern polar vortex and new insights into the workings of its atmospheric dynamics, based on cloud tracking on the night side at infrared wavelengths and on temperature data.