Short-period variations in the Earth's insolation: latitudinal and seasonal variability
K.N. Visheratin1, V.M. Fedorov2
1Russian Federal Service on Hydrometeorology and Environmental Monitoring Research and Production Association «Typhoon», Obninsk, Russia
2Lomonosov Moscow State University, Moscow, Russia
Keywords: solar radiation, short-period variations of insolation, spectral analysis, Gibbs lobes, spatial and temporal variability
Abstract
Variations in solar radiation caused by perturbations of the Earth's orbital motion by the Moon and some other planets of the solar system are studied. Short-period variations in the Earth's insolation in the range of periods 3 months to 30 years over the period from 1300 to 3000 are considered. The amplitudes, periods, and phases of the main short-period oscillations for 12 astronomical months in the latitude range 90° S to 90° N are 0. Calculations of seasonal and latitude dependences of periods and amplitudes of solar radiation arriving to the top of the atmosphere have shown that the periods of oscillations from 3 to 30 years are near constant and independent of latitude and time. Near the equinoxes, amplitudes in these oscillations caused by perturbations of the Earth's orbit by Venus, Mars, Jupiter, and Saturn are approximately symmetrical relative to the equator; near the solstices, the region of maximal amplitudes shifts towards the high latitudes of the summer hemisphere. Two closely spaced oscillations with periods of 2.6702 ± 0.0001 and 2.7154 ± 0.0001 years with different latitudinal and seasonal dependences are shown to exist in all latitudinal zones probably for the first time. The spatiotemporal variations in the 2.71-year oscillation are similar to the variations in the 18.6-year oscillation associated with the Moon, with a minimum at the equator and a maximum at high latitudes, and the 2.67-year variations are caused by perturbations of the Earth's orbit by Venus. The results of calculations of seasonal and latitudinal variations in solar radiation can be useful in climate modeling and analysis of the influence of short-period insolation variations on different geophysical and other processes.
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