Near-Infrared Light from Venus' Nightside: A Spectroscopic Analysis

Pollack, James B.; Dalton, J. B.; Grinspoon, David; Wattson, R. B.; Freedman, Richard; Crisp, David; Allen, David A.; Bézard, Bruno; Debergh, C.; Giver, L. P.; Ma, Q.; Tipping, R. H.

doi:10.1006/icar.1993.1055

Cited by 313 publications

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“…The first measurements of CO using this window were made by Bézard et al (1990) from 56 CFHT observations. Pollack et al (1993) also conducted ground-based observations to measure the 57 mean abundance of CO in the troposphere. However, the first attempt to measure spatial variations 58 in CO at 35 km was by Collard et al (1993), using 2.3 µm spectra obtained by the Near Infrared 59…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…The temperature profile has been taken from Seiff (1983), and the nominal cloud profile has been 151 taken from Pollack et al (1993 A major effect on the outgoing radiances at these near infrared wavelengths is due to cloud opacity, 161 which changes rapidly across the planet. We adopt the cloud model described in Pollack et al 162 (1993).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…The temperature profile has been taken from Seiff (1983), and the nominal cloud profile has been 151 taken from Pollack et al (1993). We assume a 75% H 2 SO 4 to 25% H 2 O concentration for the 152 sulphuric acid clouds, using Palmer and Williams (1975) A major effect on the outgoing radiances at these near infrared wavelengths is due to cloud opacity, 161 which changes rapidly across the planet.…”

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Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a Band Ratio Technique

Tsang

Taylor

Wilson

et al. 2009

Icarus

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36 37 A fast method is presented for deriving the tropospheric CO concentrations in the Venus 38atmosphere from near-infrared spectra using the night side 2.3 µm window. This is validated using 39 the spectral fitting techniques of Tsang et al. (2008a) to show that monitoring CO in the deep 40 atmosphere can be done quickly using large numbers of observations, with minimal effect from 41 cloud and temperature variations. The new method is applied to produce some 1,450 zonal mean 42 CO profiles using data from the first eighteen months of operation from the Visible and Infrared 43Thermal Imaging Spectrometer infrared mapping subsystem (VIRTIS-M-IR) on Venus Express. 44 These results show many significant long and short-term variations from the mean equator-to-pole 45 A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 increasing trend previously found from earlier Earth-and space-based observations, including a 46 possible North-South dichotomy, with interesting implications for the dynamics and chemistry of 47 the lower atmosphere of Venus. 48 491. Introduction 50 51The concentration of carbon monoxide (CO) in the troposphere (surface to 40km) of Venus was 52 first proposed to be retrievable through modeling by Kamp et al. (1988). This is possible through 53 the observation of the thermal emission window at 2.3 µm, where the radiation is escaping from the 54 deep atmosphere. For a thorough review of this topic, see Taylor et al. (1997) and Tsang et al. 55 (2008b). The first measurements of CO using this window were made by Bézard et al. (1990) from 56 CFHT observations. Pollack et al. (1993) also conducted ground-based observations to measure the 57 mean abundance of CO in the troposphere. However, the first attempt to measure spatial variations 58 in CO at 35 km was by Collard et al. (1993), using 2.3 µm spectra obtained by the Near Infrared 59Mapping Spectrometer (NIMS) on the Galileo spacecaft. 60 611.1 Collard et al. 1993 Method 62 63 These authors used Galileo/NIMS spectra at 2.3 µm from the fly-by of Venus in 1990. Rather than 64 using a spectral fitting technique, Collard et al. (1993) used ratios of radiances at two different 65 wavelengths. Between 2.20 and 2.30 µm, the absorption is purely due to CO 2 and cloud opacity, 66 whilst at 2.30 to 2.43 µm, the absorption is due to strong vibrational-rotation CO bands as well. The 67 wavelengths chosen by the authors were 2.252 µm, outside the CO band, and 2.330 µm, with strong 68 CO absorption. A distinct correlation is observed between these two wavelengths, which is due to 69 the optical depth of the cloud layer, as one might expect. However, an off-branching set of points 70 was also seen beneath the main branch. This was interpreted as being due to the increase in the CO 71 abundance at these locations on the planet, causing the increased absorption at 2. The premise for this analysis was to repeat the experiment of Collard et al. 1993 described in 111 Section 1.1, by taking radiation emitted at 2.30µm, which should be sensitiv...

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

mentioning

confidence: 99%

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Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a Band Ratio Technique

Tsang

Taylor

Wilson

et al. 2009

Icarus

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“…On the other hand, when the SO 2 mixing ratio is larger than 190 ppmv, cloud formation is independent of the SO 2 mixing ratio, because cloud formation is limited by H 2 O abundance. H 2 O abundance is constant at the present value of 30 ppmv during the calculation (DeBergh et al, 1991;Donahue and Hodges, 1993;Pollack et al, 1993).…”

Section: Cloud Modelmentioning

confidence: 99%

Stabilization of Venus’ climate by a chemical-albedo feedback

Hashimoto

Abe²

2014

Earth Planet Sp

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It has been suggested that the atmospheric concentration of SO 2 observed on Venus coincides with the equilibrium concentration over pyrite-magnetite assemblage (pyrite-magnetite buffer). If the atmospheric SO 2 abundance is controlled by the chemical reaction at the planetary surface, we expect coupling between the atmospheric SO 2 abundance and the surface temperature. Here, we propose that the pyrite-magnetite buffer combined with cloud albedo feedback controls the surface temperature on Venus. We show that this mechanism keeps the surface temperature in a rather narrow range around the presently observed value against large variations of solar luminosity and total atmospheric mass.

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“…Synthetic spectra were calculated by means of line-byline method using the HITRAN 2004 molecular database (Rothman et al, 2005) and the CO 2 HITEMP database (Wattson and Rothman, 1992;Pollack et al, 1993), the VIRA1985 model atmosphere (Keating et al, 1985), and a solar line atlas (Livingston and Wallace, 1991). The subLorentz line shape is applied for CO 2 in the same way as in Pollack et al (1993), and the Voigt line shape (Humlicek, 1992) is applied for the other gases.…”

Section: Radiative Transfer Calculationmentioning

confidence: 99%

Contrast sources for the infrared images taken by the Venus mission AKATSUKI

Takagi

Iwagami

2011

Earth Planet Sp

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A feasibility study has been carried out to look for the source of contrast that will be seen in the infrared images of Venus taken by the cameras on board AKATSUKI. This procedure used a cloud model based on the measurements of previous entry probes and radiative transfer calculations. The source of the small contrast expected in the 0.90-µm dayside image was found to be due to inhomogeneity in the cloud optical thickness, with the variations in cloud altitude and temperature having little effect. The source of the large contrast expected in the 2.26-µm nightside image was also found to be due to inhomogeneity in the cloud optical thickness. We attempted to determine the representative altitude of the cloud layers, but this could not be specified to one particular layer. The brightness expected in the 2.02-µm dayside image was found to be affected by the cloud altitude, as expected since the 2.02-µm is in a moderate CO 2 absorption band; however, it is also affected by the cloud optical thickness. The brightness expected in the 10-µm image was found to be affected mostly by temperature; however, the effects due to cloud optical thickness and cloud altitude are also important. It is necessary to use all of the information obtained at various wavelengths to gain a correct understanding of the brightness distribution of the Venus images taken by AKATSUKI.

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Near-Infrared Light from Venus' Nightside: A Spectroscopic Analysis

Cited by 313 publications

References 0 publications

Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a Band Ratio Technique

Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a Band Ratio Technique

Stabilization of Venus’ climate by a chemical-albedo feedback

Contrast sources for the infrared images taken by the Venus mission AKATSUKI

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