Dynamical properties of the Venus mesosphere from the radio-occultation experiment VeRa onboard Venus Express

Piccialli, Arianna; Tellmann, S.; Titov, D. V.; Limaye, S. S.; Khatuntsev, I.; Pätzold, M.; Häusler, B.

doi:10.1016/j.icarus.2011.07.016

Cited by 69 publications

(94 citation statements)

References 37 publications

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“…This force reduces the effective gravitational acceleration and thereby modifies the shape of the geopotential surface. This manifests itself as an equatorial bulge in the stratosphere, which was detected on Titan by stellar occultation experiments [Hubbard et al, 1993;Sicardy et al, 2006] and can be recognized on Venus in the latitudinal profiles of the isobaric levels [Limaye, 1985;Piccialli et al, 2012]. The observed equatorial bulge in Titan's stratosphere ( 30 km, Hubbard et al [1993]) is thicker than Venus' counterpart ( 2 km, Piccialli et al [2012]) because of the stronger superrotation and smaller gravitational acceleration.…”

Section: Equatorial Bulge Caused By Superrotationmentioning

confidence: 93%

“…This manifests itself as an equatorial bulge in the stratosphere, which was detected on Titan by stellar occultation experiments [Hubbard et al, 1993;Sicardy et al, 2006] and can be recognized on Venus in the latitudinal profiles of the isobaric levels [Limaye, 1985;Piccialli et al, 2012]. The observed equatorial bulge in Titan's stratosphere ( 30 km, Hubbard et al [1993]) is thicker than Venus' counterpart ( 2 km, Piccialli et al [2012]) because of the stronger superrotation and smaller gravitational acceleration. The centrifugal acceleration responsible for the equatorial bulge consists of the meridional component u 2 tan /r and the vertical component [5] The impact of the centrifugal force associated with the superrotation on the hydrostatic balance can be estimated by a scale analysis of the vertical momentum equation.…”

Section: Equatorial Bulge Caused By Superrotationmentioning

confidence: 93%

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Wind‐induced equatorial bulge in Venus and Titan general circulation models: Implication for the simulation of superrotation

Tokano

2013

Geophysical Research Letters

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[1] The centrifugal force associated with the superrotation in Venus' and Titan's middle atmosphere reduces the effective gravity and thereby modifies the shape of the geopotential surface, which manifests itself as an equatorial bulge. General circulation models (GCMs) based on the hydrostatic primitive equations cannot correctly represent this dynamics since the vertical component of the centrifugal force does not appear in the hydrostatic equation. Consequently, they are likely to underestimate the poleward pressure gradient force and superrotation in gradient wind balance. This effect can be accounted for in nonhydrostatic GCMs or in quasi-hydrostatic GCMs, in which the hydrostatic equation is supplemented by the vertical component of the centrifugal and Coriolis force and which do not make the shallow-atmosphere approximation. A quasi-hydrostatic GCM is shown to predict faster superrotation than a hydrostatic GCM run under otherwise identical conditions. Citation: Tokano, T. (2013), Wind-induced equatorial bulge in Venus and Titan general circulation models: Implication for the simulation of superrotation, Geophys. Res. Lett., 40,[4538][4539][4540][4541][4542][4543]

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Section: Equatorial Bulge Caused By Superrotationmentioning

confidence: 93%

Section: Equatorial Bulge Caused By Superrotationmentioning

confidence: 93%

Wind‐induced equatorial bulge in Venus and Titan general circulation models: Implication for the simulation of superrotation

Tokano

2013

Geophysical Research Letters

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“…Magenta: VIRA thermal profile at the equator (Seiff et al 2005). Green: VeRa profile obtained near the equator (Lee et al 2012;Piccialli et al 2012). …”

Section: Thermal Structurementioning

confidence: 99%

“…The results shown by Migliorini et al (2012) are thus consistent with the present analysis. Figure 5 shows a comparison of our retrieved thermal profile at low latitude with different data sets: (1) the VIRA equatorial profile as a function of altitude (Seiff et al 1985); (2) the equatorial profile retrieved by Irwin et al (2008) from VIRTIS-M data in the CO (1−0) band; (3) the VeRa thermal profiles reported by Lee et al (2012) and Piccialli et al (2012). There is a noticeable difference between our profile and the VIRA and VeRA profiles, especially for temperatures higher that 215 K. This temperature corresponds in our model to altitudes below 70 km.…”

Section: Thermal Structurementioning

confidence: 99%

HDO and SO₂thermal mapping on Venus

Encrenaz

Greathouse

Richter

et al. 2013

A&A

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Sulfur dioxide and water vapor, two key species of Venus photochemistry, are known to exhibit significant spatial and temporal variations above the cloud top. In particular, ground-based thermal imaging spectroscopy at high spectral resolution, achieved on Venus in January 2012, has shown evidence for strong SO 2 variations on timescales shorter than a day. We have continued our observing campaign using the TEXES high-resolution imaging spectrometer at the NASA InfraRed Telescope Facility to map sulfur dioxide over the disk of Venus at two different wavelengths, 7 μm (already used in the previous study) and 19 μm. The 7 μm radiation probes the top of the H 2 SO 4 cloud, while the 19 μm radiation probes a few kilometers below within the cloud. Observations took place on October 4 and 5, 2012. Both HDO and SO 2 lines are identified in our 7-μm spectra and SO 2 is also easily identified at 19 μm. The CO 2 lines at 7 and 19 μm are used to infer the thermal structure. An isothermal/inversion layer is present at high latitudes (above 60 N and S) in the polar collars, which was not detected in October 2012. The enhancement of the polar collar in October 2012 is probably due to the fact that the morning terminator is observed, while the January data probed the evening terminator. As observed in our previous run, the HDO map is relatively uniform over the disk of Venus, with a mean mixing ratio of about 1 ppm. In contrast, the SO 2 maps at 19 μm show intensity variations by a factor of about 2 over the disk within the cloud, less patchy than observed at the cloud top at 7 μm. In addition, the SO 2 maps seem to indicate significant temporal changes within an hour. There is evidence for a cutoff in the SO 2 vertical distribution above the cloud top, also previously observed by SPICAV/SOIR aboard Venus Express and predicted by photochemical models.

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“…Previous radio occultation experiments of the Venusian atmosphere revealed the meridional structure of the atmospheric temperature, including the horizontally near-uniform temperature below the cloud layer, the cold collar and the mid-latitude jet at cloud heights, and the warm high latitudes above clouds (Kliore and Patel 1980;Newman et al 1984;Piccialli et al 2012). The dynamical stability of the atmosphere was studied using radio occultation temperatures (Piccialli et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki

Imamura

Ando

Tellmann

et al. 2017

Earth Planets Space

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After the arrival of Akatsuki spacecraft of Japan Aerospace Exploration Agency at Venus in December 2015, the radio occultation experiment, termed RS (Radio Science), obtained 19 vertical profiles of the Venusian atmosphere by April 2017. An onboard ultra-stable oscillator is used to generate stable X-band downlink signals needed for the experiment. The quantities to be retrieved are the atmospheric pressure, the temperature, the sulfuric acid vapor mixing ratio, and the electron density. Temperature profiles were successfully obtained down to ~ 38 km altitude and show distinct atmospheric structures depending on the altitude. The overall structure is close to the previous observations, suggesting a remarkable stability of the thermal structure. Local time-dependent features are seen within and above the clouds, which is located around 48-70 km altitude. The H 2 SO 4 vapor density roughly follows the saturation curve at cloud heights, suggesting equilibrium with cloud particles. The ionospheric electron density profiles are also successfully retrieved, showing distinct local time dependence. Akatsuki RS mainly probes the low and middle latitude regions thanks to the near-equatorial orbit in contrast to the previous radio occultation experiments using polar orbiters. Studies based on combined analyses of RS and optical imaging data are ongoing.

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Dynamical properties of the Venus mesosphere from the radio-occultation experiment VeRa onboard Venus Express

Cited by 69 publications

References 37 publications

Wind‐induced equatorial bulge in Venus and Titan general circulation models: Implication for the simulation of superrotation

Wind‐induced equatorial bulge in Venus and Titan general circulation models: Implication for the simulation of superrotation

HDO and SO₂thermal mapping on Venus

Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki

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Dynamical properties of the Venus mesosphere from the radio-occultation experiment VeRa onboard Venus Express

Cited by 69 publications

References 37 publications

Wind‐induced equatorial bulge in Venus and Titan general circulation models: Implication for the simulation of superrotation

Wind‐induced equatorial bulge in Venus and Titan general circulation models: Implication for the simulation of superrotation

HDO and SO2thermal mapping on Venus

Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki

Contact Info

Product

Resources

About

HDO and SO₂thermal mapping on Venus