Solar radiation scattered in the Venus atmosphere: The Venera 11,12 data

A New Analysis of the Spectra Obtained by the Venera Missions in the Venusian Atmosphere. I. The Analysis of the Data Received from the Venera-11 Probe at Altitudes Below 37 km in the 0.44–0.66 µm Wavelength Range

“…The observational data showing what happens to radiation at various altitudes and in various spectral ranges (from ultraviolet to infrared) were obtained from Soviet and American probes in the 1970s and 1980s (Moroz et al , 2002). Within the main cloud layer, located approximately 47-50 to 57-69 km above the planetary surface (Moroz et al , 1979a;Marov et al , 1983;Ekonomov et al , 1979;Moroz et al , 1983;Moshkin et al , 1983Moshkin et al , , 1986Zasova et al , 1993), the radiation extinction at wavelengths λ > 0.44 µ m is mainly due to the scattering on aerosol particles and the true absorption in the gas and aerosols. Other processes dominate below 47-50 km.…”

“…For the wavelength range of interest, 0.44 ≤ λ ≤ 0.66 µ m, the spectral and photometric measurements carried out onboard different probes in the subcloud atmosphere were examined and analyzed by different methods in a large number of other studies (Avduevskii et al , 1976;Golovin et al , 1978Ekonomov et al , 1978Ekonomov et al , , 1979Tomasko et al , 1979Tomasko et al , , 1980Moroz et al , 1981Moroz et al , , 1983San'ko, 1980;Ragent and Blamont, 1980;Moshkin et al , 1983;Dlugach, 1988). It was found in these studies that, at short wavelengths (up to 0.55-0.60 µ m), the true absorption with a maximum at 10-20 km is observed below 30-40 km (the single scattering albedo is minimal at an altitude of about 15 km: ω 0 ≈ 0.991 ); the absorption is several times smaller below 10 km; there is no absorption below 6 km, and the light scattering there is close to conservative ( ω 0 > 0.996-0.999).…”

“…1 and 7c), where the absorption is very likely caused by other constituents of the Venusian atmosphere that have not been identified reliably so far. Among the absorbers in this spectral range, there might be such agents as Cl 2 (Pollack et al , 1980), Br 2 , NO 2 , and others; but the most probable candidate is gaseous sulfur (Moroz et al , 1979a(Moroz et al , , 1980Krasnopol'skii and Parshev, 1979), specifically, its allotropes S 3 and S 4 (San 'ko, 1980;Moroz et al , 1981Moroz et al , , 1983.…”

“…The optical scheme of the spectrophotometer, its construction, the measurement technique and conditions, and some preliminary results of this experiment are fully described in the papers by Avduevskii et al (1979), Ekonomov et al (1979, and Moroz et al (1983). The spectra were obtained in a wavelength range from 0.44 to 1.20 µ m. In the visible range, the width of the instrumental profile at the level 0.5 was ∆ ≈ 0.022 µ m. The angular field of view at this level was about 20° .…”

“…The data from the Venera-11 probe are presented. The spectrometer resolution (at a level of 0.5) shown in the plot for the visible ∆ and infrared ∆ wavelength ranges (Ekonomov et al, 1979;Moroz et al, 1983) allowed the absorption bands of gaseous ëé 2 and ç 2 é to be identified rather easily (see, e.g., Moroz et al, 1979b;Moshkin et al, 1983;Ignat'ev et al, 1997).…”