The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
Franck Montmessin - One of the best experts on this subject based on the ideXlab platform.
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Preliminary study of Venus cloud layers with polarimetric data from SPICAV/VEx
Planetary and Space Science, 2020Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M Stam, Oleg KorablevAbstract:International audienceWe present unique polarization data from the SPICAV-IR spectrometer onboard ESA's Venus Express (VEx) spacecraft and a first retrieval of cloud parameters. The polarization data have been collected from 2006 to 2010, and cover mostly the northern hemisphere, in the 0.65 to View the MathML source spectral range. They contain information about latitudinal and longitudinal variations in the properties of Venus Clouds and hazes, and about temporal variations in these properties. The degree of polarization measured on a few test orbits is in agreement with previous observations from the ground and from Pioneer Venus . Using numerical modeling to interpret the nadir observations, we retrieve mean values of View the MathML source and νeff∼0.07 for, respectively, the effective radius and variance of the cloud particle size distribution and a refractive index nr=1.42±0.02 at View the MathML source. We also derive an upper limit τh=0.17 at View the MathML source for the haze optical thickness at high latitudes. All these values are in good agreement with previous determinations
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preparing envision so2 measurements below and above Venus Clouds
EPSC-DPS Joint Meeting 2019 15-20 September 2019 Geneva Switzerland, 2020Co-Authors: Emmanuel Marcq, Franck Montmessin, Jean-loup Bertaux, Lucio Baggio, Kandis Lea Jessup, Therese Encrenaz, I Amine, M Duquesnoy, Franck Lefevre, Ann Carine VandaeleAbstract:One of the primary objectives of the preselected En-Vision M5 proposal is the monitoring of volcanogenic species in Venus’ atmosphere, one of the most prominent being sulphur dioxide (SO2). Monitoring SO2 below the Clouds can be performed on the nightside near 2.4 μm, and is one science objective of the VenSpec-H channel (P.I.: A. C. Vandaele, BIRA) onboard EnVision. Monitoring SO2 above the Clouds can be performed on the dayside in the 200-300nm range, and is the main science objective of the VenSpec-U channel (P.I.: E. Marcq, LATMOS). Here we present the analysis of two analogous datasets, namely IRTF/iSHELL ground based observations on the nightside of Venus, and the most recent reanalaysis of the Venus Express/SPICAV-UV dataset on the dayside of Venus.
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preparing envision so 2 measurements below and above Venus Clouds
EPSC-DPS Joint Meeting 2019, 2019Co-Authors: Emmanuel Marcq, Franck Montmessin, Jean-loup Bertaux, Lucio Baggio, Kandis Lea Jessup, I Amine, M Duquesnoy, Franck Lefevre, E T Encrenaz, Ann Carine VandaeleAbstract:One of the primary objectives of the preselected En-Vision M5 proposal is the monitoring of volcanogenicspecies in Venus’ atmosphere, one of the most promi-nent being sulphur dioxide (SO2). Monitoring SO2below the Clouds can be performed on the night-side near2.4μm, and is one science objective of theVenSpec-H channel (P.I.: A. C. Vandaele, BIRA) on-board EnVision. Monitoring SO2above the Cloudscan be performed on the dayside in the200-300 nmrange, and is the main science objective of theVenSpec-U channel (P.I.: E. Marcq, LATMOS). Herewe present the analysis of two analogous datasets,namely IRTF/iSHELL ground based observations onthe nightside of Venus, and the most recent reanalay-sis of the Venus Express/SPICAV-UV dataset on thedayside of Venus
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latitudinal and temporal variability of Venus Clouds and hazes observed by polarimetry with spicav ir
International Venus Conference 2016, 2016Co-Authors: Loic Rossi, Oleg Korablev, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M StamAbstract:The study of Venus’ cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze. From ground based observations Hansen and Hovenier[1], using a ra- diative transfer model including polarization, found that the main cloud layers between 50 and 70 km consist of r ≃ 1 μm radius spherical droplets of a H2SO4 -H2O solution. In the early 1980s, Kawabata[2] used the polar- ization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overly- ing haze. They found that the haze layer is composed of smaller particles with r ≃ 0.25 μm and similar re- fractive indices. Our work reproduces the method used by Hansen and Kawabata[1, 2]. We applied a radia- tive transfer model with polarization on the data of the SPICAV-IR instrument on-board ESA’s Venus Express. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
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the Clouds of Venus an overview of Venus express results
European Planetary Science Congress 2015, 2015Co-Authors: Colin Wilson, Valérie Wilquet, Franck Montmessin, N Ignatiev, Emmanuel Marcq, Anna Fedorova, W J Markiewicz, E V Petrova, O S Shalygina, Anni MaattanenAbstract:Venus is completely enveloped by Clouds. The main cloud layers stretch from altitudes of 48 – 75 km, with additional tenuous hazes found at altitudes 30 – 100 km. Clouds play a crucial role in governing atmospheric circulation, chemistry and climate on all planets, but particularly so on Venus due to the optical thickness of the atmosphere. The European Space Agency’s Venus Express (VEx) satellite has carried out a wealth of observations of Venus Clouds since its arrival at Venus in April 2006. Many VEx observations are relevant to cloud science – from imagers and spectrometers to solar, stellar and radio occultation – each covering different altitude ranges, spectral ranges and atmospheric constituents. We have formed an International Team at the International Space Science Institute to bring together scientists from each of the relevant Venus Express investigation teams as well as from previous missions, as well as those developing computational and analytical models of Clouds and hazes. The aims of the project are (1) to perform intercomparisons of cloud parameters measured using different techniques, (1) to create self-consistent reference cloud/haze models which capture not only a mean cloud structure but also its main modes of variability; and (2) to bring together modelers and observers, to reach an understanding of Clouds and hazes on Venus which matches all observables and is physically consistent. This talk will present an overview of Venus Express cloud observations of all different types, and discuss progress towards a new reference cloud model to be submitted to an update of the Venus International Reference Atmosphere.
Jean-loup Bertaux - One of the best experts on this subject based on the ideXlab platform.
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Preliminary study of Venus cloud layers with polarimetric data from SPICAV/VEx
Planetary and Space Science, 2020Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M Stam, Oleg KorablevAbstract:International audienceWe present unique polarization data from the SPICAV-IR spectrometer onboard ESA's Venus Express (VEx) spacecraft and a first retrieval of cloud parameters. The polarization data have been collected from 2006 to 2010, and cover mostly the northern hemisphere, in the 0.65 to View the MathML source spectral range. They contain information about latitudinal and longitudinal variations in the properties of Venus Clouds and hazes, and about temporal variations in these properties. The degree of polarization measured on a few test orbits is in agreement with previous observations from the ground and from Pioneer Venus . Using numerical modeling to interpret the nadir observations, we retrieve mean values of View the MathML source and νeff∼0.07 for, respectively, the effective radius and variance of the cloud particle size distribution and a refractive index nr=1.42±0.02 at View the MathML source. We also derive an upper limit τh=0.17 at View the MathML source for the haze optical thickness at high latitudes. All these values are in good agreement with previous determinations
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preparing envision so2 measurements below and above Venus Clouds
EPSC-DPS Joint Meeting 2019 15-20 September 2019 Geneva Switzerland, 2020Co-Authors: Emmanuel Marcq, Franck Montmessin, Jean-loup Bertaux, Lucio Baggio, Kandis Lea Jessup, Therese Encrenaz, I Amine, M Duquesnoy, Franck Lefevre, Ann Carine VandaeleAbstract:One of the primary objectives of the preselected En-Vision M5 proposal is the monitoring of volcanogenic species in Venus’ atmosphere, one of the most prominent being sulphur dioxide (SO2). Monitoring SO2 below the Clouds can be performed on the nightside near 2.4 μm, and is one science objective of the VenSpec-H channel (P.I.: A. C. Vandaele, BIRA) onboard EnVision. Monitoring SO2 above the Clouds can be performed on the dayside in the 200-300nm range, and is the main science objective of the VenSpec-U channel (P.I.: E. Marcq, LATMOS). Here we present the analysis of two analogous datasets, namely IRTF/iSHELL ground based observations on the nightside of Venus, and the most recent reanalaysis of the Venus Express/SPICAV-UV dataset on the dayside of Venus.
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ultraviolet albedo of Venus Clouds due to spicav and virtis joint nadir observations onboard Venus express
EPSC-DPS Joint Meeting 2019, 2019Co-Authors: Pavel Vlasov, Denis Belyaev, Jean-loup Bertaux, E Daversa, N Ignatiev, Emmanuel Marcq, Lucio Baggio, G Piccioni, R W CarlsonAbstract:In this paper we present initial results of the nadir data processing from two spectrometers that measured UV albedo of Venus Clouds onboard the Venus Express (VEX) orbiter in 2006-2014. The UVchannel of SPICAV operated in the range of115-320 nm [7], while the UV-VIS channel of VIRTIS covered the range of 300-1000 nm [8].We have selected a few tens of simultaneous nadir observations of Venus Clouds with similar pointing that allows us combining theClouds reflectancespectra at 200-600 nmusing datasets from two spectrometers
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preparing envision so 2 measurements below and above Venus Clouds
EPSC-DPS Joint Meeting 2019, 2019Co-Authors: Emmanuel Marcq, Franck Montmessin, Jean-loup Bertaux, Lucio Baggio, Kandis Lea Jessup, I Amine, M Duquesnoy, Franck Lefevre, E T Encrenaz, Ann Carine VandaeleAbstract:One of the primary objectives of the preselected En-Vision M5 proposal is the monitoring of volcanogenicspecies in Venus’ atmosphere, one of the most promi-nent being sulphur dioxide (SO2). Monitoring SO2below the Clouds can be performed on the night-side near2.4μm, and is one science objective of theVenSpec-H channel (P.I.: A. C. Vandaele, BIRA) on-board EnVision. Monitoring SO2above the Cloudscan be performed on the dayside in the200-300 nmrange, and is the main science objective of theVenSpec-U channel (P.I.: E. Marcq, LATMOS). Herewe present the analysis of two analogous datasets,namely IRTF/iSHELL ground based observations onthe nightside of Venus, and the most recent reanalay-sis of the Venus Express/SPICAV-UV dataset on thedayside of Venus
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latitudinal and temporal variability of Venus Clouds and hazes observed by polarimetry with spicav ir
International Venus Conference 2016, 2016Co-Authors: Loic Rossi, Oleg Korablev, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M StamAbstract:The study of Venus’ cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze. From ground based observations Hansen and Hovenier[1], using a ra- diative transfer model including polarization, found that the main cloud layers between 50 and 70 km consist of r ≃ 1 μm radius spherical droplets of a H2SO4 -H2O solution. In the early 1980s, Kawabata[2] used the polar- ization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overly- ing haze. They found that the haze layer is composed of smaller particles with r ≃ 0.25 μm and similar re- fractive indices. Our work reproduces the method used by Hansen and Kawabata[1, 2]. We applied a radia- tive transfer model with polarization on the data of the SPICAV-IR instrument on-board ESA’s Venus Express. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
Denis Belyaev - One of the best experts on this subject based on the ideXlab platform.
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ultraviolet albedo of Venus Clouds due to spicav and virtis joint nadir observations onboard Venus express
EPSC-DPS Joint Meeting 2019, 2019Co-Authors: Pavel Vlasov, Denis Belyaev, Jean-loup Bertaux, E Daversa, N Ignatiev, Emmanuel Marcq, Lucio Baggio, G Piccioni, R W CarlsonAbstract:In this paper we present initial results of the nadir data processing from two spectrometers that measured UV albedo of Venus Clouds onboard the Venus Express (VEX) orbiter in 2006-2014. The UVchannel of SPICAV operated in the range of115-320 nm [7], while the UV-VIS channel of VIRTIS covered the range of 300-1000 nm [8].We have selected a few tens of simultaneous nadir observations of Venus Clouds with similar pointing that allows us combining theClouds reflectancespectra at 200-600 nmusing datasets from two spectrometers
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so2 monitoring above Venus Clouds using vex spicav uv nadir observations
The EGU General Assembly, 2012Co-Authors: Emmanuel Marcq, Denis Belyaev, Franck Montmessin, Jean-loup Bertaux, Anna FedorovaAbstract:SO2 in the upper atmosphere of Venus is an important tracer of (i) its recent (within 10 million years) geological activity, (ii) the chemistry and photo-chemistry of sulfur-bearing species, including H2SO4-H2O underlying Clouds and (iii) general circulation of the atmosphere bringing SO2-rich air up to levels where photo-chemical destruction occurs. The first monitoring, using Pioneer Venus and ground-based data, showed a two order-of-magnitude decrease from 1980 to 1995 [Esposito et al., 1988]. Latitudinal variations were also constrained in the early 1990s, and exhibited an increasing observable SO2 column density with increasing latitude [Zasova et al., 1993; Na et al., 1994]. Measurements of SO2 have resumed since 2006 mainly thanks to SPICAV/SOIR instrument on-board Venus Express, and first studies showed an opposite latitudinal gradient as well as relatively high SO2 abundance, comparable to the early 1980s [Belyaev et al., 2008; Marcq et al., 2011]. Here we show the results for the 2007-2010 epoch, using an improved version of Marcq et al.'s (2011) model able to cope with non-nadir observations. Strong variability is observed within short (daily) timescales , but there is evidence for two distinct regimes, the most frequent being identical to the situation in 2006 already published (rather high abundances, negative latitudinal gradient), but starting in late 2009, a new regime very similar to the situation during the early 1990s (low abundances, positive latitudinal gradients) has been observed, alternating with the common regime within a few Earth months. Simple modeling suggests that fluctuations in the general circulation and/or sporadic change in SO2 below 65 km may cause the alternation between both regimes. Bibliography: Esposito et al., JGR 93 (1988) Zasova et al., Icarus 105 (1993) Na et al., Icarus 112 (1994) Belyaev et al., JGR 113 (2008), Marcq et al., Icarus 211 (2011)
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vertical profiling of so 2 and so above Venus Clouds by spicav soir solar occultations
Icarus, 2012Co-Authors: Denis Belyaev, A. Mahieux, Oleg Korablev, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, Yuk L Yung, Xi ZhangAbstract:New measurements of sulfur dioxide (SO2) and monoxide (SO) in the atmosphere of Venus by SPICAV/SOIR instrument onboard Venus Express orbiter provide ample statistics to study the behavior of these gases above Venus’ Clouds. The instrument (a set of three spectrometers) is capable to sound atmospheric structure above the Clouds in several observation modes (nadir, solar and stellar occultations) either in the UV or in the near IR spectral ranges. We present the results from solar occultations in the absorption ranges of SO_2 (190–230 nm, and at 4 μm) and SO (190–230 nm). The dioxide was detected by the SOIR spectrometer at the altitudes of 65–80 km in the IR and by the SPICAV spectrometer at 85–105 km in the UV. The monoxide’s absorption was measured only by SPICAV at 85–105 km. We analyzed 39 sessions of solar occultation, where boresights of both spectrometers are oriented identically, to provide complete vertical profiling of SO_2 of the Venus’ mesosphere (65–105 km). Here we report the first firm detection and measurements of two SO_2 layers. In the lower layer SO_2 mixing ratio is within 0.02–0.5 ppmv. The upper layer, also conceivable from microwave measurements by Sandor et al. (Sandor, B.J., Todd Clancy, R., Moriarty-Schieven, G., Mills, F.P. [2010]. Icarus 208, 49–60) is characterized by SO_2 increasing with the altitude from 0.05 to 2 ppmv, and the [SO_2]/[SO] ratio varying from 1 to 5. The presence of the high-altitude SO_x species could be explained by H_2SO_4 photodissociation under somewhat warmer temperature conditions in Venus mesosphere. At 90–100 km the content of the sulfur dioxide correlates with temperature increasing from 0.1 ppmv at 165–170 K to 0.5–1 ppmv at 190–192 K. It supports the hypothesis of SO_2 production by the evaporation of H_2SO_4 from droplets and its subsequent photolysis at around 100 km.
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Vertical profiling of SO 2 and SO above Venus' Clouds by SPICAV/SOIR solar occultations
Icarus, 2012Co-Authors: Denis Belyaev, A. Mahieux, Oleg Korablev, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, Yuk L Yung, Xi ZhangAbstract:New measurements of sulfur dioxide (SO2) and monoxide (SO) in the atmosphere of Venus by SPICAV/SOIR instrument onboard Venus Express orbiter provide ample statistics to study the behavior of these gases above Venus’ Clouds. The instrument (a set of three spectrometers) is capable to sound atmospheric structure above the Clouds in several observation modes (nadir, solar and stellar occultations) either in the UV or in the near IR spectral ranges. We present the results from solar occultations in the absorption ranges of SO_2 (190–230 nm, and at 4 μm) and SO (190–230 nm). The dioxide was detected by the SOIR spectrometer at the altitudes of 65–80 km in the IR and by the SPICAV spectrometer at 85–105 km in the UV. The monoxide’s absorption was measured only by SPICAV at 85–105 km. We analyzed 39 sessions of solar occultation, where boresights of both spectrometers are oriented identically, to provide complete vertical profiling of SO_2 of the Venus’ mesosphere (65–105 km). Here we report the first firm detection and measurements of two SO_2 layers. In the lower layer SO_2 mixing ratio is within 0.02–0.5 ppmv. The upper layer, also conceivable from microwave measurements by Sandor et al. (Sandor, B.J., Todd Clancy, R., Moriarty-Schieven, G., Mills, F.P. [2010]. Icarus 208, 49–60) is characterized by SO_2 increasing with the altitude from 0.05 to 2 ppmv, and the [SO_2]/[SO] ratio varying from 1 to 5. The presence of the high-altitude SO_x species could be explained by H_2SO_4 photodissociation under somewhat warmer temperature conditions in Venus mesosphere. At 90–100 km the content of the sulfur dioxide correlates with temperature increasing from 0.1 ppmv at 165–170 K to 0.5–1 ppmv at 190–192 K. It supports the hypothesis of SO_2 production by the evaporation of H_2SO_4 from droplets and its subsequent photolysis at around 100 km.
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sulfur mono and dioxides above Venus Clouds from spicav soir solar occultations
European Geophysical Union General Assembly 2011, 2011Co-Authors: Denis Belyaev, A. Mahieux, Oleg Korablev, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, Yuk L Yung, Xi ZhangAbstract:In the lower layer SO2 (65-80 km) mixing ratio varies around 0.02-0.5 ppmv, and in the upper layer (85-105 km) it increases with altitude from 0.05 to 2 ppmv, while [SO2]/[SO] ratio is around 1 to 5. The presence of the SOx abundance at high altitudes is analyzed on the basis of H2SO4 photodissociation and temperature conditions in Venus mesosphere. At levels 90-100 km the content of sulfur dioxide was found to increase with temperature from 0.1 ppmv at 165-170 K to 0.5-1 ppmv at 190-192 K. This behavior confirms a concept about SO2 production in this altitude region by the evaporation of H2SO4 from droplets and its subsequent photolysis around 100 km.
Oleg Korablev - One of the best experts on this subject based on the ideXlab platform.
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Preliminary study of Venus cloud layers with polarimetric data from SPICAV/VEx
Planetary and Space Science, 2020Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M Stam, Oleg KorablevAbstract:International audienceWe present unique polarization data from the SPICAV-IR spectrometer onboard ESA's Venus Express (VEx) spacecraft and a first retrieval of cloud parameters. The polarization data have been collected from 2006 to 2010, and cover mostly the northern hemisphere, in the 0.65 to View the MathML source spectral range. They contain information about latitudinal and longitudinal variations in the properties of Venus Clouds and hazes, and about temporal variations in these properties. The degree of polarization measured on a few test orbits is in agreement with previous observations from the ground and from Pioneer Venus . Using numerical modeling to interpret the nadir observations, we retrieve mean values of View the MathML source and νeff∼0.07 for, respectively, the effective radius and variance of the cloud particle size distribution and a refractive index nr=1.42±0.02 at View the MathML source. We also derive an upper limit τh=0.17 at View the MathML source for the haze optical thickness at high latitudes. All these values are in good agreement with previous determinations
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latitudinal and temporal variability of Venus Clouds and hazes observed by polarimetry with spicav ir
International Venus Conference 2016, 2016Co-Authors: Loic Rossi, Oleg Korablev, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M StamAbstract:The study of Venus’ cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze. From ground based observations Hansen and Hovenier[1], using a ra- diative transfer model including polarization, found that the main cloud layers between 50 and 70 km consist of r ≃ 1 μm radius spherical droplets of a H2SO4 -H2O solution. In the early 1980s, Kawabata[2] used the polar- ization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overly- ing haze. They found that the haze layer is composed of smaller particles with r ≃ 0.25 μm and similar re- fractive indices. Our work reproduces the method used by Hansen and Kawabata[1, 2]. We applied a radia- tive transfer model with polarization on the data of the SPICAV-IR instrument on-board ESA’s Venus Express. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
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Retrieval of Venus' Clouds and hazes properties with polarimetric data from SPICAV/VEx
2015Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, N Bott, D M Stam, Oleg KorablevAbstract:The study of Venus’ cloud layers is important in or- der to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze.From ground based observations, Hansen and Hovenier[3], using a radiative transfer model includ- ing polarization, found that the main cloud layers be- tween 50 and 70 km consist of r ∼ 1 μm radius spher- ical droplets of a H SO -H O solution. In the early 1980s, Kawabata[4] used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overlying haze. They found that the haze layer is composed of smaller parti- cles with r ∼ 0.25 μm and similar refractive indices. Our work reproduces the method used by Hansen and Kawabata[3, 4]. We applied a radiative transfer model with polarization on the polarization data of the SPICAV-IR instrument on-board ESA’s Venus Ex- press. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
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retrieval of Venus Clouds and hazes properties with polarimetric data from spicav vex
European Planetary Science Congress 2015, 2015Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, N Bott, D M Stam, Oleg KorablevAbstract:The study of Venus’ cloud layers is important in or- der to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze.From ground based observations, Hansen and Hovenier[3], using a radiative transfer model includ- ing polarization, found that the main cloud layers be- tween 50 and 70 km consist of r ∼ 1 μm radius spher- ical droplets of a H SO -H O solution. In the early 1980s, Kawabata[4] used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overlying haze. They found that the haze layer is composed of smaller parti- cles with r ∼ 0.25 μm and similar refractive indices. Our work reproduces the method used by Hansen and Kawabata[3, 4]. We applied a radiative transfer model with polarization on the polarization data of the SPICAV-IR instrument on-board ESA’s Venus Ex- press. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
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Preliminary study of Venus cloud layers with polarimetric data from SPICAV/VEx
Planetary and Space Science, 2015Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, Daphne M. Stam, Oleg KorablevAbstract:We present unique polarization data from the SPICAV-IR spectrometer onboard ESA's Venus Express (VEx) spacecraft and a first retrieval of cloud parameters. The polarization data have been collected from 2006 to 2010, and cover mostly the northern hemisphere, in the 0.65 to View the MathML source spectral range. They contain information about latitudinal and longitudinal variations in the properties of Venus Clouds and hazes, and about temporal variations in these properties. The degree of polarization measured on a few test orbits is in agreement with previous observations from the ground and from Pioneer Venus . Using numerical modeling to interpret the nadir observations, we retrieve mean values of View the MathML source and νeff∼0.07 for, respectively, the effective radius and variance of the cloud particle size distribution and a refractive index nr=1.42±0.02 at View the MathML source. We also derive an upper limit τh=0.17 at View the MathML source for the haze optical thickness at high latitudes. All these values are in good agreement with previous determinations.
Anna Fedorova - One of the best experts on this subject based on the ideXlab platform.
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Preliminary study of Venus cloud layers with polarimetric data from SPICAV/VEx
Planetary and Space Science, 2020Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M Stam, Oleg KorablevAbstract:International audienceWe present unique polarization data from the SPICAV-IR spectrometer onboard ESA's Venus Express (VEx) spacecraft and a first retrieval of cloud parameters. The polarization data have been collected from 2006 to 2010, and cover mostly the northern hemisphere, in the 0.65 to View the MathML source spectral range. They contain information about latitudinal and longitudinal variations in the properties of Venus Clouds and hazes, and about temporal variations in these properties. The degree of polarization measured on a few test orbits is in agreement with previous observations from the ground and from Pioneer Venus . Using numerical modeling to interpret the nadir observations, we retrieve mean values of View the MathML source and νeff∼0.07 for, respectively, the effective radius and variance of the cloud particle size distribution and a refractive index nr=1.42±0.02 at View the MathML source. We also derive an upper limit τh=0.17 at View the MathML source for the haze optical thickness at high latitudes. All these values are in good agreement with previous determinations
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latitudinal and temporal variability of Venus Clouds and hazes observed by polarimetry with spicav ir
International Venus Conference 2016, 2016Co-Authors: Loic Rossi, Oleg Korablev, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, D M StamAbstract:The study of Venus’ cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze. From ground based observations Hansen and Hovenier[1], using a ra- diative transfer model including polarization, found that the main cloud layers between 50 and 70 km consist of r ≃ 1 μm radius spherical droplets of a H2SO4 -H2O solution. In the early 1980s, Kawabata[2] used the polar- ization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overly- ing haze. They found that the haze layer is composed of smaller particles with r ≃ 0.25 μm and similar re- fractive indices. Our work reproduces the method used by Hansen and Kawabata[1, 2]. We applied a radia- tive transfer model with polarization on the data of the SPICAV-IR instrument on-board ESA’s Venus Express. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
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Retrieval of Venus' Clouds and hazes properties with polarimetric data from SPICAV/VEx
2015Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, N Bott, D M Stam, Oleg KorablevAbstract:The study of Venus’ cloud layers is important in or- der to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze.From ground based observations, Hansen and Hovenier[3], using a radiative transfer model includ- ing polarization, found that the main cloud layers be- tween 50 and 70 km consist of r ∼ 1 μm radius spher- ical droplets of a H SO -H O solution. In the early 1980s, Kawabata[4] used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overlying haze. They found that the haze layer is composed of smaller parti- cles with r ∼ 0.25 μm and similar refractive indices. Our work reproduces the method used by Hansen and Kawabata[3, 4]. We applied a radiative transfer model with polarization on the polarization data of the SPICAV-IR instrument on-board ESA’s Venus Ex- press. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
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retrieval of Venus Clouds and hazes properties with polarimetric data from spicav vex
European Planetary Science Congress 2015, 2015Co-Authors: Loic Rossi, Franck Montmessin, Jean-loup Bertaux, Emmanuel Marcq, Anna Fedorova, N Bott, D M Stam, Oleg KorablevAbstract:The study of Venus’ cloud layers is important in or- der to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the Clouds and haze.From ground based observations, Hansen and Hovenier[3], using a radiative transfer model includ- ing polarization, found that the main cloud layers be- tween 50 and 70 km consist of r ∼ 1 μm radius spher- ical droplets of a H SO -H O solution. In the early 1980s, Kawabata[4] used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overlying haze. They found that the haze layer is composed of smaller parti- cles with r ∼ 0.25 μm and similar refractive indices. Our work reproduces the method used by Hansen and Kawabata[3, 4]. We applied a radiative transfer model with polarization on the polarization data of the SPICAV-IR instrument on-board ESA’s Venus Ex- press. Our aim is to better constrain haze and cloud particles at the top of Venus’s Clouds, as well as their spatial and temporal variability.
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the Clouds of Venus an overview of Venus express results
European Planetary Science Congress 2015, 2015Co-Authors: Colin Wilson, Valérie Wilquet, Franck Montmessin, N Ignatiev, Emmanuel Marcq, Anna Fedorova, W J Markiewicz, E V Petrova, O S Shalygina, Anni MaattanenAbstract:Venus is completely enveloped by Clouds. The main cloud layers stretch from altitudes of 48 – 75 km, with additional tenuous hazes found at altitudes 30 – 100 km. Clouds play a crucial role in governing atmospheric circulation, chemistry and climate on all planets, but particularly so on Venus due to the optical thickness of the atmosphere. The European Space Agency’s Venus Express (VEx) satellite has carried out a wealth of observations of Venus Clouds since its arrival at Venus in April 2006. Many VEx observations are relevant to cloud science – from imagers and spectrometers to solar, stellar and radio occultation – each covering different altitude ranges, spectral ranges and atmospheric constituents. We have formed an International Team at the International Space Science Institute to bring together scientists from each of the relevant Venus Express investigation teams as well as from previous missions, as well as those developing computational and analytical models of Clouds and hazes. The aims of the project are (1) to perform intercomparisons of cloud parameters measured using different techniques, (1) to create self-consistent reference cloud/haze models which capture not only a mean cloud structure but also its main modes of variability; and (2) to bring together modelers and observers, to reach an understanding of Clouds and hazes on Venus which matches all observables and is physically consistent. This talk will present an overview of Venus Express cloud observations of all different types, and discuss progress towards a new reference cloud model to be submitted to an update of the Venus International Reference Atmosphere.
