Altitudinal dependence of aerosol volumetric scattering coefficient in the Saturn’s atmosphere. II. The northern hemisphere latitudinal belts
| Ovsak, OS, 1Karimov, AM, 1Lysenko, PG 1Fesenkov Astrophysical Institute, Almaty, Kazakhstan |
| Kinemat. fiz. nebesnyh tel (Online) 2021, 37(4):18-34 |
| https://doi.org/10.15407/kfnt2021.04.018 |
| Start Page: Dynamics and Physics of Solar System Bodies |
| Language: Ukrainian |
Abstract: The altitude dependences of volumetric aerosol scattering coefficient have been determined for the five latitudinal belts of the Saturn Northern Hemisphere. A probable vertical structure of the aerosol component in the range of atmospheric pressure 0.06...10 bar has been constructed. For this purpose, we have used the our previous work analyzing results of 2015 spectrophotometric measurements data of giant planet latitudinal belts 17N, 33N, 49N, 66N and 80N in the absorption bands of methane at 727 nm and 619 nm. In the studied range of altitude levels of Saturn’s atmosphere, the ubiquitous presence of aerosols was found, without signs of the presence of purely gas interlayers there. The largest values of the volumetric aerosol scattering coefficient 2⋅10-6 cm-1 are determined in the midlatitude belt 49N, and the smallest 10-8 cm-1 in the circumpolar belt 80N. In the studied altitude range of the atmosphere, four areas of aerosol thickening were identified, within which the volumetric aerosol scattering coefficient reaches its maximum values. The presence of particles of the most powerful aerosol layer in the atmosphere of Saturn was found at altitude with a pressure of 0.06 bar. With immersion in the atmosphere depth, the scattering coefficient of this layer increases to maximum values. In all the studied latitudinal belts, except for 80N, two highest clusters are formed, in which the maxima of the volumetric scattering coefficient of atmospheric aerosol are located near altitudinal levels with averaged pressures of 0.26 bar and 0.45 bar. These thickenings are separated in height by an interlayer of less dense aerosol. When immersed in the atmosphere, the aerosol volumetric scattering coefficient is reduced significantly in the 0.45...2 bar pressure range. The third in order of magnitude aerosol thickening was found in this altitude region of the atmosphere in all latitudinal belts, except 80N. The maxima of the volumetric aerosol scattering coefficient are located here near the level with a pressure of1 bar. Even deeper we revealed in the range of atmospheric pressure 2...6 bar the fourth in order of magnitude stretched in height aerosol thickening. It consists of an upper and a lower part, with maxima of the volumetric scattering coefficient of aerosol located near the levels of 2.7 bar and 4.4 bar, respectively. The model parameters of aerosol particles were used in the calculations are: an effective radius of 1.4 Mm and a dispersion of 0.07 for the modified gamma particle size distribution function, as well as the real part of the complex refractive index of1.44. These model characteristics of aerosols are probably close to the averaged parameters of real particles in the studied altitude part of the Saturnian atmosphere in the 66N latitudinal belt, as well as for the pressure range of 0.06...1.5 bar atmosphere in the 33N belt. At the same time, signs of a possible significant difference between the model and real parameters of aerosol particles at all studied altitude levels of the atmosphere in the 17N and 49N belts of the giant planet were revealed. |
| Keywords: aerosol, atmosphere, latitudinal belts, Saturn, vertical structure |
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