The influence of solar activity on seasonal variation of the methane absorption in Saturn's atmosphere

1Vidmachenko, AP
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2015, 31(3):38-53
Start Page: Dynamics and Physics of Solar System Bodies
Language: Russian

Our analysis of observational results on the methane absorption distribution in Saturn’s disk for the period from 1965 to 2011 showed seasonal changes at the levels of visible clouds and haze. The methane absorption changes along the central meridian at equinoxes in 1966 and 1995 are in opposition to similar data obtained at the equinox in 1980. According to the observations at the equinox in 2009, expected (as in 1980) differences in the methane absorption at mid-latitudes between the southern and northern hemispheres of Saturn did not happen, although physical and orbital characteristics of Saturn in the equinoxes for 1966 and 1980 as well as for 1995 and 2009 practically repeated. For a couple of years before the equinox in 1966, 1980 and 1995, solar activity was rather high, and before the equinox in 2009 the Sun was in a low activity. Some studies show that if the condensation and convection are accounted for, dynamic time constant in the middle troposphere of Saturn can be several tens of hours. Then a big change of insolation in the ultraviolet spectral region can lead to significant short-term dynamic changes. At the time of the equinox in 2009 convection in Saturn’s atmosphere remained at the lowest possible level, and so after leaving the ring shadows deep cloud layers in the winter northern hemisphere remained “frozen” state with no active processes on the Sun. So, closed up to this point by the rings, inactive cloud layer remained at the same level below the tropopause. This allowed one to detect freely strong above-cloud layer of gaseous methane and ammonia. Because of this, the methane absorption in the low-activity before winter hemisphere remained almost the same and equal to the absorption of the summer hemisphere.

Keywords: Saturn, seasonal methane absorption, Sun

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