 |
| Titel |
Venus Water Vapour Profiles Obtained by SOIR/VEx |
| VerfasserIn |
Sarah Chamberlain, Valerie Wilquet, Arnaud Mahieux, Séverine Robert, Ian Thomas, Ann Carine Vandaele, Jean-Loup Bertaux |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108569
|
| Publikation (Nr.) |
 EGU/EGU2015-8331.pdf |
|
|
|
|
|
| Zusammenfassung |
| We present up-to-date observations of the water vapour profile at the Venus terminator,
between altitudes of 70 – 110km. The data were obtained by the Solar Occultation in the
InfraRed (SOIR) instrument on board Venus Express (VEx). The SOIR instrument allows
observations of trace gas profiles at altitudes within the Venus lower thermosphere and
mesosphere. Due to the observational technique, all observations are taken at the Venus
terminator, on either or both of the evening and morning side of the planet and covering
almost all latitudes. These are key locations for study as the mesosphere/thermosphere
altitudes correspond to the transition in dynamical regime from a retrograde zonal flow to
sub-solar to antisolar flow (approximately 90 km) and at these altitudes we expect a steeper
than normal temperature gradient across the terminator which would drive chemical
reactions and dynamical flows. Water vapour in the mesosphere is involved in the cloud
formation process and contributes to several chemical cycles. Isotopologue ratio
studies also contribute towards understanding the evolution of the Venus climate and
atmosphere. Determining the abundance, distribution and variability of water vapour is
therefore a key element to understanding the development, maintenance and links
between dynamical features, important chemical cycles and the evolution of the Venus
atmosphere.
Both water vapour isotopologues are targeted simultaneously in the majority of dedicated
SOIR water vapour observations. H2O is detected between 70 – 110km and HDO is detected
between 70 – 95km altitude. Early SOIR water vapour observations were published in 2007
and 2008. Previous results show a depletion in the volume mixing ratio (VMR) at 85km in
both HDO and H2O and an increase in HDO/H2O ratio above the clouds. No noticeable
temporal variability was detected.
Numerous subsequent H2O and HDO SOIR observations have been obtained between
2007 – 2014 and with recent improvements in instrument calibration, data reduction and a
long base line of data, a new analysis has become pertinent. |
|
|
|
|
|
|