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Multilayer modeling of the aureole photometry during the Venus transit: Comparison between SDO/HMI and VEx/SOIR data

dc.contributor.authorPere, C.
dc.contributor.authorTanga, P.
dc.contributor.authorWidemann, T.
dc.contributor.authorBendjoya, P.
dc.contributor.authorMahieux, A.
dc.contributor.authorWilquet, V.
dc.contributor.authorVandaele, A.C.
dc.date2016
dc.date.accessioned2016-12-01T11:33:12Z
dc.date.available2016-12-01T11:33:12Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/4566
dc.descriptionContext. The mesosphere of Venus is a critical range of altitudes in which complex temperature variability has been extensively studied by the space mission Venus Express (VEx) during its eight-year mission (2006-2014). In particular, the Solar Occultation in the InfraRed (SOIR) instrument probed the morning and evening terminator in the 70-170 km altitude region, at latitudes extending from pole to pole, using spectroscopic multiband observations collected during occultations of the Sun at the limb. Data collected at different epochs and latitudes show evidence of short and medium timescale variability as well as latitudinal differences. Spatial and temporal variability is also predicted in mesospheric and thermospheric terminator models with lower boundary conditions at 70 km near cloud tops. Aims. The Venus transit on June 5-6, 2012 was the first to occur with a spacecraft in orbit around Venus. It has been shown that sunlight refraction in the mesosphere of Venus is able to provide useful constraints on mesospheric temperatures at the time of the transit. The European Space Agency's Venus Express provided space-based observations of Venus during the transit. Simultaneously, the Venus aureole photometry was observed using ground-based facilities and solar telescopes orbiting Earth (NASA's Solar Dynamic Observatory, JAXA's HINODE). As the properties of spatial and temporal variability of the mesosphere are still debated, the opportunity of observing it at all latitudes at the same time, offered by the transit, is rather unique. In this first paper, we establish new methods for analyzing the photometry of the so-called aureole that is produced by refraction of the solar light, and we investigate the choice of physical models that best reproduce the observations. Methods. We compared the refractivity profile obtained by SOIR at the time of the June 2012 transit to the aureole photometry. For this goal, we explored isothermal and multilayered refraction models of the terminator atmosphere based on the vertical density profile obtained by VeX/SOIR at a latitude of + 49° and successfully compared it to the aureole photometry observed from space by the HMI instrument of the Solar Dynamic Observatory (SDO). Results. We obtain an independent constraint of 4.8 ± 0.5 km for the aerosol scale height in the upper haze region above 80 km. We show that a full multiple-layer approach is required to adequately reproduce the aureole photometry, which appears to be sensitive to several second-order variations in the vertical refractivity.
dc.languageeng
dc.titleMultilayer modeling of the aureole photometry during the Venus transit: Comparison between SDO/HMI and VEx/SOIR data
dc.typeArticle
dc.subject.frascatiPhysical sciences
dc.audienceScientific
dc.subject.freeIonosphere
dc.subject.freeNASA
dc.subject.freeObservatories
dc.subject.freeOrbits
dc.subject.freePhotometry
dc.subject.freePlanets
dc.subject.freePoles
dc.subject.freeRefraction
dc.subject.freeSatellites
dc.subject.freeSpace flight
dc.subject.freeLower boundary conditions
dc.subject.freeMethods:observational
dc.subject.freePlanets and satellites: atmospheres
dc.subject.freePlanets and satellites: individual: venus
dc.subject.freeSpace-based observations
dc.subject.freeSpatial and temporal variability
dc.subject.freeTerrestrial planets
dc.subject.freeVertical density profiles
dc.subject.freeInterplanetary flight
dc.source.titleAstronomy and Astrophysics
dc.source.volume595
dc.source.pageA115
Orfeo.peerreviewedYes
dc.identifier.doi10.1051/0004-6361/201628528
dc.identifier.scopus2-s2.0-84995767645


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