Seasonal Changes in the Activity Factor of Jupiter’s Hemispheres and Their Relationship with Solar Activity and Orbital Motion

The authors analyze the long-term changes in the reflective properties of Jupiter’s atmosphere in order to study seasonal variations and the influence of solar activity. Jupiter has a very dynamic atmosphere consisting primarily of hydrogen and helium. Trace amounts of ammonia, methane, and other compounds form the visible cloud layers and haze above the clouds. The planet’s powerful magnetosphere plays an important role in the formation of the observed phenomena. The significant eccentricity of Jupiter’s orbit (e ≈ 0.0485) causes the solar energy input to the planet’s atmosphere to vary by 21% between perihelion and aphelion. The Northern Hemisphere receives significantly more energy because its summer solstice occurs during the planet’s passage through perihelion. This causes variations in the physical characteristics of the atmosphere and indicates the presence of seasonal changes. In order to quantify these changes, the brightness ratio of the northern and southern tropical and temperate regions A_J = B_N/B_S as a factor of photometric activity of atmospheric processes were used. Analysis of these data for the period 1960–2025 has revealed a clear periodicity in A_J changes with a period of approximately 11.87 years, which corresponds to Jupiter’s orbital period and indicates seasonal atmospheric restructuring processes. The effects of orbital eccentricity (a 21% variation in insolation) and solar activity (notably the 22-year Hale cycle and UV radiation) on Jupiter’s various atmospheric layers are analyzed. The characteristic radiative relaxation time of Jupiter’s atmosphere is found to be approximately 3.4 years (τ_R ≈ 1.07 × 10⁸ s) during intervals of coordinated orbital and solar forcings. A phase of imbalance from 1995 to 2012 and its subsequent recovery have been documented, accompanied by a decrease in the effective radiative constant to approximately 2.5 years (τ_R ≈ 0.79 × 10⁸ s), likely reflecting an enhanced influence of solar activity on the upper atmosphere.