Preliminary results on the Venus atmosphere from the Venera 8 descent module

Marov, M. Ya.; Avduevsky, V. S.; Borodin, N. F.; Ékonomov, A. P.; Kerzhanovich, V. V.; Lysov, V. P.; Moshkin, B. Y.; Rozhdestvensky, M. K.; Ryabov, O. L.

doi:10.1016/0019-1035(73)90014-6

Cited by 52 publications

(14 citation statements)

References 7 publications

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“…We assume that the coefficient is proportional to atmospheric density, specific heat capacity at constant pressure, and wind speed (compare equations (6)–(8) in the work of Keszthelyi and Denlinger []). Griffiths and Fink [] provide density and heat capacity for the atmospheres of both Earth and Venus and winds speeds measured at the surface of Venus on the order of 1 m/s [ Avduevskij et al , ; Marov et al , ], and likely not larger than 2 m/s [ Lorenz , ]. This results in a forced convection coefficient h conv =208 W/(m 2 K).…”

Section: Model Of Eruption Thermal Emissionmentioning

confidence: 99%

“…The Venus Monitoring Camera (VMC) [Markiewicz et al, 2007] on the ESA mission Venus Express [Svedhem et al, 2007] acquired 1 μm images of the nightside of Venus from 2006 to 2015. Shalygin et al [2015] report the observation of several transient bright spots at fixed locations visible through the clouds moving with the superrotating atmosphere.…”

Section: Introductionmentioning

confidence: 99%

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Search for active lava flows with VIRTIS on Venus Express

et al. 2017

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The Visible Infrared Thermal Imaging Spectrometer (VIRTIS) instrument on Venus Express observed thermal emission from the surface of Venus at 1 μm wavelength and thus would have detected sufficiently bright incandescent lava flows. No eruptions were detected in the observations between April 2006 and October 2008, covering an area equivalent to 7 times the planets surface on separate days. Models of the cooling of lava flows on Earth are adapted to Venus ambient conditions to predict thermal emission based on effusion rate. Taking into account the blurring of surface thermal emission by the atmosphere, the VIRTIS images would detect eruptions with effusion rates above 500 to 1000 m3/s. On Earth such eruptions occur but are rare. Based on an eruption rate and duration distribution fitted to historical data of three terrestrial volcanos, we estimate that only a few percent of all eruptions are detectable. With these assumptions the VIRTIS data can constrain the rate of effusive volcanism on Venus to be less than about 300 km3/yr, at least an order of magnitude higher than existing constraints. There remains a large uncertainty because of unknown properties of lava flows on Venus. Resolving flows in radar imaging and their thickness in altimetry might help to better constrain these properties. While VIRTIS data do not represent a significant constraint on volcanism, an optimized instrument with a 20 times better signal‐to‐noise ratio would likely be able to detect effusion rates on the order of 50 m3/s.

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Section: Model Of Eruption Thermal Emissionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Search for active lava flows with VIRTIS on Venus Express

et al. 2017

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“…The stated uncertainties in temperature measurements of the Venera probes is about + 1.5% or +2 K to +9 K [Kuzrnin and Maroy, 1974;Marov et al, 1973]. There are also significant altitude uncertainties discussed by Marov et al [1973] for Venera 8, +3 km, which in light of a lapse rate of-*8 K/km, could introduce temperature discrepancies of +25 K. These uncertainties, coupled with those stated earlier for the Pioneer Venus temperatures and altitudes, would appear capable of explaining discrepancies in static stability and differences in detailed shape of the temperature profiles. The large temperature differences between Venera 9 and 10 may also be due in part to measurement uncertainties.…”

Section: Temperature Differences Between the Venera And Pioneermentioning

confidence: 99%

Measurements of thermal structure and thermal contrasts in the atmosphere of Venus and related dynamical observations: Results From the four Pioneer Venus Probes

Seiff¹,

Kirk²,

Young³

et al. 1980

J. Geophys. Res.

299

134

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Thermal structure of the atmosphere of Venus, and differences in structure with latitude (up to 60°) and clock hour (from midnight to 8 A.M.) have been measured in situ from an altitude of 126 km to the surface by instruments on the four Pioneer Venus entry probes. Several indications from the preliminary analyses are confirmed by the current analysis: Thermal contrasts below 45 km are a few K, with the mid‐latitudes warmer than both equatorial and the high latitudes. Sizeable temperature and pressure differences with latitude develop in the clouds (25 K and 20 mbar at the 200 mbar level). At 30° latitude, diurnal differences were small throughout the lower atmosphere from midnight to 7 A.M. A major stable layer 25 km deep exists just below the clouds. Waves of global extent were observed within this layer. A locally stable layer is indicated in the deep atmosphere, between 10 and 20 km, at latitudes up to 30°. In the middle cloud and immediately below the deep stable layer, the atmosphere is approximately neutrally stable, and there is evidence for convective overturning below the stable layer. Just above the clouds, the lapse rate becomes stable, and a ‘stratosphere’ begins which extends upwards to 110 km, becoming isothermal above 85 km. The stratospheric temperature profiles were essentially the same in three widely separated soundings. Upward of 110 km, there is evidence of large amplitude temperature oscillations with altitude, believed to signify the presence of large amplitude waves, perhaps thermal tides. By comparing data of several experiments, it is found that the large diurnal variations in the upper atmosphere begin at an altitude ∼115 km. Agreement of structure data from other Pioneer Venus experiments with the present results is generally excellent. Our measurements of the winds derived from Doppler data agree well with DLBI results and indicate a retrograde zonal velocity of 113 m/s at 63 km altitude and 30° latitude. The zonal winds predicted at cloud levels from pressure differences between 60° latitude and the mid‐latitude probes by assumption of cyclostrophic balance are in first order agreement with the observed winds. At latitudes below ∼30°, however, cyclostrophic balance of the zonal winds is not the dominant process. At altitudes from 60 to 105 km, the measured pressure differences and the assumption of cyclostrophic balance indicate zonal wind velocities peaking at 155 m/s at 68 km, remaining above 120 m/s up to 95 km, then decreasing rapidly.

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“…The consistency of redundant radio observations Copyright ¸ 1980 by the American Geophysical Union. fled the assumption which had been used to infer wind speed profiles from the Doppler tracking of several Russian Venera spacecraft [Kerzhanovitch et al, 1972;Marov et al, 1973;Keldysh, 1977] that the wind direction remained westward from the cloud top to the surface. The fact that different Venera descents had yielded quite different wind speed profiles suggested, however, that there might be large (of the order of 100%) variations of the zonal winds in the lower atmosphere, possibly associated with changes in the local solar time.…”

Section: Introductionmentioning

confidence: 99%

Zonal and meridional circulation of the lower atmosphere of Venus determined by radio interferometry

Counselman

Gourevitch²,

King³

et al. 1980

J. Geophys. Res.

146

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From earth‐based Doppler and interferometric radio observations we determined the paths, in three dimensions and as functions of time, taken by the Pioneer probes as they fell to the surface of Venus. From the motion of each probe below about 65‐km altitude we were able to infer the ambient wind velocity with an estimated uncertainty of about 1 m s−1 in each vector component. The magnitude of the velocity was about 1 m s−1 or less near the surface of the planet and about 100 m s−1 near 65‐km altitude at all four probe locations. Distinct strata of high wind shear were centered at altitudes of 15, 45, and 60 km, where the atmosphere is most stable against verticle motion. Except within a few kilometers of the surface, the wind velocity was always directed within a few degrees of due west. At the day and the night probe sites, which were separated by 100° in longitude and 3° in latitude, the altitude profiles of the westward velocity were virtually identical. Thus the dominant motion of the lower atmosphere seems to be a retrograde zonal rotation. Eddies appear to account for most of the instantaneous meridional velocity. However, in the radiatively heated middle cloud layer, between 50‐ and 55‐km altitude, equatorward flow of 1–7 m s−1 was observed for all four probes. These observations, coupled with other observations of ∼10 m s−1 poleward average meridional velocity for cloud top features at about 65‐km altitude, suggest that within the clouds a thermally driven mean meridional circulation is superimposed on the much more rapid zonal rotation.

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Preliminary results on the Venus atmosphere from the Venera 8 descent module

Cited by 52 publications

References 7 publications

Search for active lava flows with VIRTIS on Venus Express

Search for active lava flows with VIRTIS on Venus Express

Measurements of thermal structure and thermal contrasts in the atmosphere of Venus and related dynamical observations: Results From the four Pioneer Venus Probes

Zonal and meridional circulation of the lower atmosphere of Venus determined by radio interferometry

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