Venus mesosphere ALMA observations

DOI

Water vapor and sulfur compounds are key species in the photochemistry of Venus mesosphere. These species, together with mesospheric temperatures, exhibit drastic temporal variations, both on short timescales (diurnal and day-to-day) as well on long timescales, far from being understood. We targeted CO, SO, H_2_O and SO_2_ transitions in the submillimeter range using the Atacama Large Millimeter Array (ALMA) to study their spatial and temporal variations. Four sets of observations were acquired on different dates in November 2011 during the first ALMA Early Science observation Cycle 0. Venus angular diameter was about 11" with an illumination factor of 92%, so that mostly the day side of the planet was mapped. Assuming a nominal CO abundance profile, we retrieved vertical temperature profiles over the entire disk as a function of latitude and local time. Temperature profiles were later used to retrieve SO, SO_2_, and H_2_O. We used H_2_O as a tracer for water assuming a D/H enrichment of 200 times the terrestrial value. We derived 3-D maps of mesospheric temperatures in the altitude range 70-105km. SO, SO_2_, and H_2_O are characterized by a negligible abundance below ~85km followed by an increase with altitude in the upper mesosphere. Disk-averaged SO abundances present a maximum mixing ratio of 15.0+/-3.1ppb on November 26 followed the next day by a minimum value of 9.9+/-1.2ppb. Due to a very low S/N, SO_2_ could only be derived from the disk-averaged spectrum on the first day of observation revealing an abundance of 16.5+/-4.6ppb. We found a SO_2_/SO ratio of 1.5+/-0.4. Global maps of SO reveal strong variations both with latitude and local time and from day to day with abundance ranging from <1 to 15ppb. H_2_O disk-averages retrievals reveal a steady decrease from November 14 to 27, with the abundance varying from 3.6+/-0.6ppm on the first day to 2.9+/-0.7ppm on the last day. H_2_O maps reveal a slightly higher abundance on the evening side compared to the morning side and a strong depletion between the first and the second day of observation.

Identifier
DOI http://doi.org/10.26093/cds/vizier.36060053
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/A+A/606/A53
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/606/A53
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/606/A53
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/A+A/606/A53
Provenance
Creator Piccialli A.; Moreno R.; Encrenaz T.; Fouchet T.; Lellouch E.; Widemann T.
Publisher CDS
Publication Year 2017
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Interdisciplinary Astronomy; Natural Sciences; Physics; Solar System Astronomy