Temperature (EuroVenus Episode 4)
April 03rd, 2016
The surface of Venus experiences air temperatures of around 450 degrees centigrade, due to an enormous greenhouse warming caused by the massive atmosphere of carbon dioxide. But high up in the atmosphere, above the cloud layer, Venus' mesosphere is surprisingly like our stratosphere, with much cooler temperatures and many earthlike dynamical features. In the past few years, new observations have revealed this region of the atmosphere to be surprisingly dynamic.
In this film, we present four different techniques being used by EuroVenus researchers to study atmospheric temperatures at different altitudes. We start with Silvia Tellmann in Cologne, who has been analyzing radio occultation data from Venus Express, which yields tempreature and density profiles in the 40-90 km altitude range - this includes part of the lower atmosphere ("troposphere", through the cloud region into the mesosphere. Here there is evidence of oscillations in the temperature profile - these are evidence of a phenomenon known as gravity waves, similar to the ripples on a river when it flows over an obstacle. Just as in that example, there is increasing evidence that some of these waves are caused by surface topography, even though these wave are observed many tens of kilometres above the surface.
Next we join Arianna Piccialli, of the Paris Observatory, in the wintry landscape of the NOEMA sub-mm interferometer array at the Plateau de Bure in France. This again allows mapping of temperatures - and winds - in the mesosphere of Venus. The analysis of theseobservation is ongoing so the results are not yet known, but the mapping capability of this instrument would be complentary to the profiles obtained from radio science.
We return to Cologne to hear from Pia Krause, who has been observing temperatures (and winds) even higher in the atmosphere using an infrared heterodyne spectrometer built in Cologne, called THIS (Tunable Heterodyne Infrared Spectrometer).
Finally, we hear from Arnaud Mahieux in Brussels, part of the SOIR (Solar Occultation in the Infra Red) experiment on Venus Express. This instrument watches sunsets and sunrises on Venus - by observing how sunlight is absorbed during these events, it is sensitive to atmospheric parameters including temperature, up to extremely high altitudes, as high as 170 km, right at the edge of space (for context, the Venus Express orbiter sometimes came as low as 130 km altitude, far lower than the altitudes probed by SOIR).
Taken together, these ground- and space-based observations allow a picture to be built of of atmospheric temperatures from the lower atmosphere right up to the edge of space.
In this film, we present four different techniques being used by EuroVenus researchers to study atmospheric temperatures at different altitudes. We start with Silvia Tellmann in Cologne, who has been analyzing radio occultation data from Venus Express, which yields tempreature and density profiles in the 40-90 km altitude range - this includes part of the lower atmosphere ("troposphere", through the cloud region into the mesosphere. Here there is evidence of oscillations in the temperature profile - these are evidence of a phenomenon known as gravity waves, similar to the ripples on a river when it flows over an obstacle. Just as in that example, there is increasing evidence that some of these waves are caused by surface topography, even though these wave are observed many tens of kilometres above the surface.
Next we join Arianna Piccialli, of the Paris Observatory, in the wintry landscape of the NOEMA sub-mm interferometer array at the Plateau de Bure in France. This again allows mapping of temperatures - and winds - in the mesosphere of Venus. The analysis of theseobservation is ongoing so the results are not yet known, but the mapping capability of this instrument would be complentary to the profiles obtained from radio science.
We return to Cologne to hear from Pia Krause, who has been observing temperatures (and winds) even higher in the atmosphere using an infrared heterodyne spectrometer built in Cologne, called THIS (Tunable Heterodyne Infrared Spectrometer).
Finally, we hear from Arnaud Mahieux in Brussels, part of the SOIR (Solar Occultation in the Infra Red) experiment on Venus Express. This instrument watches sunsets and sunrises on Venus - by observing how sunlight is absorbed during these events, it is sensitive to atmospheric parameters including temperature, up to extremely high altitudes, as high as 170 km, right at the edge of space (for context, the Venus Express orbiter sometimes came as low as 130 km altitude, far lower than the altitudes probed by SOIR).
Taken together, these ground- and space-based observations allow a picture to be built of of atmospheric temperatures from the lower atmosphere right up to the edge of space.