Clouds and Hazes of Venus

Titov, Dmitrij; Ignatiev, Nikolay; McGouldrick, Kevin; Wilquet, V.; Wilson, Colin

doi:10.1007/s11214-018-0552-z

Cited by 121 publications

(157 citation statements)

References 185 publications

(281 reference statements)

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“…Lavega 2017] and the deep radiance penetrates the clouds toward the outer space relatively easier in this region [Titov 2018]. This is consistent with previous observations from Earth, see [Tavenner 2008], and results from other missions as summarized by [Peralta 2018].…”

Section: Mid-latitude Region (Latitudes 30-60º)supporting

confidence: 85%

“…REGION (LATITUDES 0-30º) The maps show an equatorial belt with relatively high cloud opacity. The equatorial belt of Venus is dominated by generally thick clouds [Titov 2018]. The low integrated radiance observed all around the equator is explained by the thermal radiation coming from the layers below the lower clouds, getting absorbed by the thick equatorial clouds, causing lower values in average at the equator.…”

Section: Discussionmentioning

confidence: 99%

“…A preliminary version of these polar views was previously presented for the southern hemisphere by [Cardesín-Moinelo 2008] and briefly discussed by [Titov 2018]. These new maps have been reprocessed covering both hemispheres and include various updates, in particular we now use better emission angle corrections based on [Longobardo 2012], new grid (5x5 degrees in latitude/longitude) and some other adjustments and filtering of incorrect and meaningless data.…”

Section: Longituginal Views Of Infrared Atmospheric Windowmentioning

confidence: 99%

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Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express

Cardesín‐Moinelo

Piccioni

Migliorini

et al. 2020

Icarus

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One of the striking features about Venus atmosphere is its temporal variability and dynamics, with a chaotic polar vortex, large-scale atmospheric waves, sheared features, and variable winds that depend on local time and possibly orographic features. The aim of this research is to combine data accumulated over several years and obtain a global VENUS LOWER CLOUDS IN THE INFRARED ATMOSPHERIC WINDOWSObservations at different wavelengths, including ultra-violet (UV), visible (VIS) and nearinfrared (NIR) spectral ranges, and comparison of observed features are very important to investigate cloud properties. As largely demonstrated in the past and more recently shown with the Akatsuki data [Limaye 2018a], observations in the NIR bands are able to probe clouds at lower altitudes with respect to the observations in the UV because these are less sensitive to scattering by small particles. However, the NIR CO2 transparency windows can contribute to probe deeper in the atmosphere, and hence when same structures are found in the UV, VIS and NIR these might indicate that the features extend from the cloud top to a depth of one scale height and larger cloud particles are detected.The wavelengths analysed in the present paper, centred around 1.74 and 2.25μm, belong to radiance coming mainly from below the cloud layers. Radiative transfer models indicate that the radiance at these bands originates about 10-20 and 20-30 km above the surface, respectively, see [Allen and Crawford 1984, Crisp 1991, Carlson 1991 and also the recent review by [Titov 2018]. This thermal radiation from the lower layers goes up through the cloud layer and is attenuated mostly by the lower clouds with differing optical depths [Titov 2018, Sánchez-Lavega 2017]. Therefore, the features observed at these wavelengths show mainly the spatial variations in the opacity of the lower to middle clouds, around 44-48 km altitude. [Peralta 2017a] These clouds have been studied since decades by Earth telescope observations, see [Tavenner 2008] and references therein and by several space missions, starting with the fly-by of Venus from the Galileo NIMS instrument [Carlson 1991], later by VIRTIS on Venus Express [Sánchez-Lavega 2008, Hueso 2012] and more recently by Akatsuki [Nakamura 2016] with the IR2 camera as described by [Satoh 2016, 2017] and [Peralta 2018], which also includes a good overview of Venus cloud observations at 2.3μm since 1978. These clouds are known to be composed mainly of sulphuric acid covering the whole planet [Marcq 2018, Titov 2018], dynamically elongated by the strong zonal winds coming from the super-rotation and travelling towards the poles with the meridional winds caused by the Hadley cell [Sánchez-Lavega 2018]. The general structure and dynamics of the clouds have been analysed and compared extensively with General Circulation Models [Lebonnois 2010, Garate-Lopez 2018, Kashimura 2019, Ando 2019].Space Agency, the Italian Space Agency (ASI), French Space Agency (CNES) and other national agencies that supported the Venus Express mission an...

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Section: Mid-latitude Region (Latitudes 30-60º)supporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Longituginal Views Of Infrared Atmospheric Windowmentioning

confidence: 99%

See 1 more Smart Citation

Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express

Cardesín‐Moinelo

Piccioni

Migliorini

et al. 2020

Icarus

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“…This scenario seems consistent with downwelling and clouds' evaporation (McGouldrick et al, 2012) (hence, lower optical thickness) west of the disruption and upwelling accompanied by formation of clouds (larger optical thickness) on its eastside. This upwelling combined with the increased H 2 SO 4 vapor pressure and the larger nucleation rates expected for the high H 2 SO 4 concentrations of the clouds (Sihto et al, 2009; Titov et al, 2018) can help the cloud condensation nuclei (CNN) of submicron size to overcome the Kelvin barrier (i.e., greater saturation pressure over smaller particles) and grow to small droplets with radii of ∼1 μm (Imamura & Hashimoto, 2001), probably explaining the abundance of smaller particles observed in Figure 3c.…”

Section: Resultsmentioning

confidence: 99%

A Long‐Lived Sharp Disruption on the Lower Clouds of Venus

Peralta

Navarro

Vun

et al. 2020

Geophysical Research Letters

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Planetary‐scale waves are thought to play a role in powering the yet unexplained atmospheric superrotation of Venus. Puzzlingly, while Kelvin, Rossby, and stationary waves manifest at the upper clouds (65–70 km), no planetary‐scale waves or stationary patterns have been reported in the intervening level of the lower clouds (48–55 km), although the latter are probably Lee waves. Using observations by the Akatsuki orbiter and ground‐based telescopes, we show that the lower clouds follow a regular cycle punctuated between 30°N and 40°S by a sharp discontinuity or disruption with potential implications to Venus's general circulation and thermal structure. This disruption exhibits a westward rotation period of ∼4.9 days faster than winds at this level (∼6‐day period), alters clouds' properties and aerosols, and remains coherent during weeks. Past observations reveal its recurrent nature since at least 1983, and numerical simulations show that a nonlinear Kelvin wave reproduces many of its properties.

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“…Furthermore, as on Earth, a possible consequence of the atmospheric ionization could be the presence of lightning generated by the separation of electric charge residing on water-ice particles within the cloud layers. A recent detailed discussion of the evidence of optical lightning can be found in Titov et al (2018).…”

Section: Discussionmentioning

confidence: 99%

Revisiting the cosmic-ray induced Venusian ionization with the Atmospheric Radiation Interaction Simulator (AtRIS)

Herbst

Banjac

Nordheim

2019

A&A

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Context. Cosmic ray bombardment represents a major source of ionization in planetary atmospheres. The higher the energy of the primary cosmic ray particles, the deeper they can penetrate into the atmosphere. In addition, incident high energy cosmic ray particles induce extensive secondary particle cascades ("air showers") that can contain up to several billion secondary particles per incoming primary particle. To quantify cosmic ray-induced effects on planetary atmospheres it is therefore important to accurately model the entire secondary particle cascade. This is particularly important in thick planetary atmospheres where the secondary particle cascades can develop extensively before being absorbed by the surface. Aims. Inside the Venusian atmosphere, cosmic rays are the dominant driver for the ionization below an altitude of ∼100 km. In this work we revisit the numerical modeling of the galactic and solar cosmic-ray induced atmospheric ionization for cosmic ray ions from Hydrogen (Z = 1) to Nickel (Z = 28) and investigate the influence of strong solar energetic particle events inside the Venusian atmosphere.Methods. The Atmospheric Radiation Interaction Simulator (AtRIS), a newly developed simulation code to model the interaction of the near-(exo)planet particle and radiation field with the (exo)planetary atmosphere, was used to revisit the modeling of the altitudedependent Venusian atmospheric ionization. Thereby, spherical geometry, the newest version of Geant4 (10.5) as well as the newest Geant4-based hadronic and electromagnetic interaction models were utilized. Results. Based on our new model approach we show that previous studies may have underestimated the galactic cosmic ray-induced atmospheric ion pair production by, amongst others, underestimating the influence of galactic cosmic ray protons above 1 TeV/nuc. Furthermore, we study the influence of 71 exceptionally strong solar particle events that were measured as Ground Level Enhancements at the Earth's surface, and show a detailed analysis of the impact of such strong events on the Venusian ionization. Key words. Sun: activity -planets and satellites: terrestrial planets -planets and satellites: atmospheres Article published by EDP Sciences A124, page 1 of 11 A&A 624, A124 (2019) primary cosmic ray particle (Z = 1-28) E prim = [1 MeV/nuc -1 TeV/nuc] electromagnetic hadronic muonic

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Clouds and Hazes of Venus

Cited by 121 publications

References 185 publications

Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express

Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express

A Long‐Lived Sharp Disruption on the Lower Clouds of Venus

Revisiting the cosmic-ray induced Venusian ionization with the Atmospheric Radiation Interaction Simulator (AtRIS)

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