On the altitudinal level dependence of aerosol volume scattering coefficient in the Saturn’s atmosphere. I. Integral disk
| Ovsak, OS |
| Kinemat. fiz. nebesnyh tel (Online) 2021, 37(3):46-57 |
| https://doi.org/10.15407/kfnt2021.03.046 |
| Start Page: Dynamics and Physics of Solar System Bodies |
| Language: Ukrainian |
Abstract: Modern state of researches on the vertical structure, composition and microphysical parameters of aerosol component in the atmosphere of Saturn is considered. The disadvantages of applying the methods of model analysis of the giant planet atmospheres with the compulsory assignment of the number and parameters of aerosol layers artificially included in the model of the vertical structure of the atmosphere are noted. The advantages of the effective optical depth method using are listed. This method makes it possible to determine a qualitative picture of the altitudinal distribution of cloud cover in the giant planet atmospheres, and also to calculate a number of microphysical parameters of their aerosol component without preliminary designation of a model vertical structure. The reflectivity measurements data of Saturn integral disk in the spectral absorption bands of methane at 619, 727, 842, 864, and 887 nm are in use. The aerosol volumetric scattering coefficient dependence on the pressure in the upper atmosphere is calculated. The method of effective optical depth was applied. Model assumptions, quantitative ratios of the main atmospheric gases, and parameters of the size distribution function of aerosol particles are listed. On the studied altitude levels of Saturn's atmosphere, the continuous presence of aerosols with varying scattering properties was found. The altitude levels with the highest aerosols thickening have been determined. The most powerful in the planet's atmosphere cloud system has two maxima of the volume scattering coefficient at levels of about and 430 mbar and an intermediate peak of about 1.0 bar. In the pressure range 2.2...8.0 bar, there is an extended aerosol layer with a scattering maximum determined in the pressure range of 3.8—4.8 bar, depending on the analyzed methane absorption band. The revealed significant dispersion differences in the combined dependence of the volumetric aerosol scattering coefficient indicate a probable change in the radius and / or nature of aerosol particles in the deep levels of Saturn's atmosphere. |
| Keywords: atmospheric aerosol, maximum scattering levels, Saturn, vertical structure |
References:
1. O. V. Morozhenko, Methods and Results of Remote Sensing of Planetary Atmospheres (Naukova Dumka, Kyiv, 2004) [in Ukrainian].
2. S. K. Atreya, M. H. Wonga, T. C. Owen, P. R. Mahaffy, H. B. Niemann, I. de Pater, P. Drossart, and Th. Encrenaz. A comparison of the atmospheres of Jupiter and Saturn: Deep atmospheric composition, cloud structure, vertical mixing, and origin, Planet. Space Sci. 47, 1243–1262 (1999).
https://doi.org/10.1016/S0032-0633(99)00047-1
3. O. I. Bugaenko, Zh. M. Dlugach, A. V. Morozhenko, and E. G. Yanovitskij. On optical properties of the cloud layer of Saturn in the visible region of the spectrum, Sol. Syst. Res. 9, 13–21 (1975).
4. O. I. Bugaenko and A. V. Morozhenko. Physical characteristics of the upper layers of Saturn’s atmosphere, Adv. Space Res. 1, 183–186 (1981).
https://doi.org/10.1016/0273-1177(81)90500-7
5. J. W. Chamberlain. The atmosphere of Venus near cloud top, Astrophys. J. 141, 1184–1205 (1965).
https://doi.org/10.1086/148207
6. R. Courtin, D. Gautier, A. Marten, B. Bézard, and R. Hanel. The composition of Saturn’s atmosphere at Northern temperate latitudes from Voyager IRIS spectra: NH3, PH3, C2H2, C2H6, CH3D, CH4, and the Saturnian D/H isotopic ratio, Astrophys. J. 287, 899–916 (1984).
https://doi.org/10.1086/162748
7. Z. M. Dlugach, A. V. Morozhenko, A. P. Vid’machenko, and E. G. Yanovitskij. Investigations of the optical properties of Saturn’s atmosphere carried out at the main astronomical observatory of the Ukrainian Academy of Sciences, Icarus 54, 319–336 (1983).
https://doi.org/10.1016/0019-1035(83)90201-4
8. L. N. Fletcher, K. H. Baines, T. W. Momary, A. P. Showman, P. G. J. Irwin, G. S. Orton, M. Roos-Serote, and C. Merlet. Saturn’s tropospheric composition and clouds from Cassini/VIMS 4.6—5.1 μm nightside spectroscopy, Icarus 214, 510–533 (2011).
https://doi.org/10.1016/j.icarus.2011.06.006
9. L. N. Fletcher, S. Guerlet, G. S. Orton, R. G. Cosentino, T. Fouchet, P. G. J. Irwin, L. Li, F. M. Flasar, N. Gorius, and R. Morales-Juberías. Disruption of Saturn’s quasi-periodic equatorial oscillation by the great northern storm, Nature Astron. 1, 765–770 (2017).
https://doi.org/10.1038/s41550-017-0271-5
10. L. N. Fletcher, G. S. Orton, N. A. Teanby, P. G. J. Irwin, and G. L. Bjoraker. Methane and its isotopologues on Saturn from Cassini/CIRS observations, Icarus 199, 351–167 (2009).
https://doi.org/10.1016/j.icarus.2008.09.019
11. L. P. Giver. Intensity measurements of the CH4 bands in the region 4350 Å to 10 600 Å, J. Quant. Spectrosc. Radiat. Transfer 19, 311–322 (1978).
https://doi.org/10.1016/0022-4073(78)90064-X
12. E. Karkoschka. Spectrophotometry of the Jovian planets and Titan at 300 to 1000 nm wavelength: The methane spectrum, Icarus 111, 967–982 (1994).
https://doi.org/10.1006/icar.1994.1139
13. K. Kawata. Circular polarization of sunlight reflected by planetary atmosphere, Icarus 33, 217–233 (1978).
https://doi.org/10.1016/0019-1035(78)90035-0
14. T. T. Koskinen and S. Guerlet. Atmospheric structure and helium abundance on Saturn from Cassini/UVIS and CIRS observations, Icarus 307, 161–171 (2018).
https://doi.org/10.1016/j.icarus.2018.02.020
15. G. F. Lindal. The atmosphere of Neptune: An analysis of radio occultation data with Voyager 2, Astron. J. 103, 967–982 (1992).
https://doi.org/10.1086/116119
16. W. Macy, Jr. An analysis of Saturn’s methane 3ν3 band profiles in the terms of an inhomogeneous atmosphere, Icarus 29, 49–56 (1976).
https://doi.org/10.1016/0019-1035(76)90101-9
17. M. I. Mishchenko, The Program for Computing Far-Field Light Scattering by Polydisperse Homogeneous Spherical Particles Using the Lorenz-Mie Theory.
18. A. V. Morozhenko. Jovian cloud stratification, Sov. Astron. Lett. 10, 323–325 (1984).
19. A. V. Morozhenko. New determination of monochromatic methane absorption coefficients with regard to the thermal conditions in the atmospheres of giant planets. IV. Jupiter and Saturn, Kinematics Phys. Celestial Bodies 23, 245–257 (2007).
https://doi.org/10.3103/S0884591307060025
20. A. V. Morozhenko and A. S. Ovsak. Dependence of the aerosol component of optical thickness and the relative concentration of methane on depth in atmospheres of giant planets, Kinematics Phys. Celestial Bodies 25, 173–181 (2009).
https://doi.org/10.3103/S0884591309040011
21. A. V. Morozhenko and A. S. Ovsak. On the possibility of separation of aerosol and methane absorption in the long-wavelength spectral range for giant planets, Kinematics Phys. Celestial Bodies 31, 225–231 (2015).
https://doi.org/10.3103/S0884591315050074
22. A. V. Morozhenko and A. S. Ovsak. On the probable change of the radius and nature of aerosol particles in the deep layers of Jupiter’s atmosphere, Kinematics Phys. Celestial Bodies 33, 88–93 (2017).
https://doi.org/10.3103/S0884591317020052
23. A. V. Morozhenko, A. S. Ovsak, and P. P. Korsun. Vertical structure of Jupiter’s cloud layer before and after the impact by comet Shoemaker–Levy 9, Kinematics Phys. Celestial Bodies 11, 1–13 (1995).
24. A. V. Morozhenko, A. S. Ovsak, A. P. Vid’machenko, V. G. Tejfel, and P. G. Lysenko. Imaginary part of the refractive index of aerosol in latitudinal belts of Jupiter’s disc, Kinematics Phys. Celestial Bodies 32, 30–37 (2016).
https://doi.org/10.3103/S0884591316010062
25. O. J. Mousis, D. H. Atkinson, and the Hera Team. The Hera Saturn entry probe mission. A proposal in response to ESA call for a medium size mission opportunity in ESA’s science programme for launch in 2019-2030 (M5) (2016). https://arxiv.org/abs/1510.07685
26. A. S. Ovsak. Upgraded technique to analyze the vertical structure of the aerosol component of the atmospheres of giant planets, Kinematics Phys. Celestial Bodies 29, 291–300 (2013).
https://doi.org/10.3103/S0884591313060056
27. A. S. Ovsak. Vertical structure of cloud layers in the atmospheres of giant planets. I. On the influence of variations of some atmospheric parameters on the vertical structure characteristics, Sol. Syst. Res. 49, 46–53 (2015).
https://doi.org/10.1134/S0038094615010050
28. A. S. Ovsak. Changes in the characteristics of the upper layers of the Jovian atmosphere from the data on the integral observations of the planetary disk, Kinematics Phys. Celestial Bodies 31, 25–32 (2015).
https://doi.org/10.3103/S0884591315010067
29. A. S. Ovsak. Variations of the volume scattering coefficient of aerosol in the Jovian atmosphere from observations of the planetary disk, Kinematics Phys. Celestial Bodies 31, 197–204 (2015).
https://doi.org/10.3103/S0884591315040066
30. A. S. Ovsak. On determining the vertical structure of the aerosol component in the atmosphere of Saturn, Kinematics Phys. Celestial Bodies 34, 37–51 (2018).
https://doi.org/10.3103/S088459131801004X
31. A. S. Ovsak. On possible changes in the physical characteristics of the aerosol in the deep layers of the atmosphere of Saturn, Kinematics Phys. Celestial Bodies 35, 28–37 (2019).
https://doi.org/10.3103/S0884591319010057
32. O. Ovsak and N. Kostogryz. The method of computer analysis a vertical structure of aerosol component in the atmospheres of the Giant planets, in Proc. AGU Chapman Conf. on Crossing Boundaries in Planetary Atmospheres: From Earth to Exoplanets, Annapolis, Md., June 24–27, 2013 (American Geophysical Union, 2013), abstract no. 1677256.
33. A. S. Ovsak and A. V. Morozhenko. Corrected spectral dependence of the imaginary part of the refractive index of aerosol in Jupiter’s atmosphere in the short-wavelength spectral range, Kinematics Phys. Celestial Bodies 33, 239–244 (2017).
https://doi.org/10.3103/S088459131705004X
34. A. S. Ovsak, V. G. Tejfel, and P. G. Lysenko. Vertical structure of the volume scattering coefficient of aerosol in latitude belts of Jupiter’s disc, Kinematics Phys. Celestial Bodies 32, 181–188 (2016).
https://doi.org/10.3103/S0884591316040061
35. A. S. Ovsak, V. G. Tejfel, A. P. Vid’machenko, and P. G. Lysenko. Zonal differences in the vertical structure of the cloud cover of Jupiter from the measurements of the methane absorption bands at 727 and 619 nm, Kinematics Phys. Celestial Bodies 31, 119–130 (2015).
https://doi.org/10.3103/S0884591315030058
36. S. Pérez-Hoyos, J. F. Sanz-Requena, A. Sánchez-Lavega, P. G. J. Irwin, and A. Smith. Saturn’s tropospheric particles phase function and spatial distribution from Cassini ISS 2010–11 observations, Icarus 277, 1–18 (2016).
https://doi.org/10.1016/j.icarus.2016.04.022
37. B. Ragent, D. S. Colburn, K. A. Rages, et al. The clouds of Jupiter: Results of the Galileo Jupiter mission probe Nephelometer experiment, J. Geophys. Res.: Planets 103, 22891–22909 (1998).
https://doi.org/10.1029/98JE00353
38. M. T. Roman, D. Banfield, and P. J. Gierasch. Saturn’s cloud structure inferred from Cassini ISS, Icarus 225, 93–110 (2013).
https://doi.org/10.1016/j.icarus.2013.03.015
39. A. Sánchez-Lavega, R. Hueso, and S. Pérez-Hoyos. The three-dimensional structure of Saturn’s equatorial jet at cloud level, Icarus 187, 510–519 (2007).
https://doi.org/10.1016/j.icarus.2006.10.022
40. R. Santer and A. Dollfus. Optical reflectance polarimetry of Saturn’s globe and rings: IV. Aerosols in the upper atmosphere of Saturn, Icarus 48, 496 (1981).
https://doi.org/10.1016/0019-1035(81)90060-9
41. L. A. Sromovsky, R. Y. Baines, and P. M. Fry. Saturn’s south polar cloud composition and structure inferred from 2006 Cassini/VIMS spectra and ISS images, Icarus 344, 113398 (2020).
https://doi.org/10.1016/j.icarus.2019.113398
42. V. G. Tejfel, L. A. Usoltzeva, and G. A. Kharitonova. The spectral characteristics and probable structure of the cloud layer of Saturn, in Planetary Atmospheres: Proc. 40th IAU Symp., Marfa, Tex., Oct. 26–31, 1969, Ed. by C. Sagan, T. C. Owen, and H. J. Smith (Reidel, Dordrecht, 1971), p. 375.
https://doi.org/10.1007/978-94-010-3063-2_49
43. T. Temma, N. J. Chanover, A. A. Simon-Miller, D. A. Glenar, J. J. Hillman, and D. M. Kuehn. Vertical structure modeling of Saturn’s equatorial region using high spectral resolution imaging, Icarus 175, 464–489 (2005).
https://doi.org/10.1016/j.icarus.2004.11.006
44. A. P. Vid’machenko, Zh. M. Dlugach, and A. V. Morozhenko. Nature of the optical inhomogeneity of Saturn’s disk, Astron. Vestn. 17, 216–224 (1983).
45. R. West. Clouds and aerosols in Saturn’s atmosphere, Presented at Saturn in the 21st Century: Saturn Sci. Conf., Madison, Wisc., Aug. 4–7, 2014. http://www.ssec.wisc.edu/meetings/21st_saturn/program/Oral_ Presentati-ons/Oral_Presentations_08062014/1.%20West_oral_SatSciConf2014.pdf.
46. R. V. Yelle, J. Serigano, T. T. Koskinen, S. M. Horst, M. E. Perry, R. S. Perryman, and J. H. Waite. Thermal structure and composition of Saturn’s upper atmosphere from Cassini/Ion Neutral Mass Spectrometer measurements, Geophys. Res. Lett. 45, 10951–10958 (2018).
https://doi.org/10.1029/2018GL078454
47. R. E. Young. The Galileo probe mission to Jupiter: Science overview, J. Geophys. Res.: Planets 103, 22775–22790 (1998).
https://doi.org/10.1029/98JE01051