Spectrum analysis of Jupiters great red spot parameters: area, rotation, latitude and longitude (1963–67)

Abstract

Spectrum analysis of Jupiters great red spot area, rotation, longitude, and latitude, for the period 1963–1967, has been performed. The methods of maximum entropy, power spectrum (Blackman–Tukey approach), Fourier, and autocorrelation have been employed to detect periodicities in the variation of these parameters. The method of successive approximations was applied to the area time-series, and periods of 25, 16, 5 and 3 months and a trend ∼32 months were identified and an analytical expression fit was given, with an accuracy of 78%. Only some periods (6–18 months) describe the main trends of the variation, the shorter (2–5 months) exhibit a stochastic variability, while the longer ones which approach the total record represent a trend. The obtained significant periods and long term trends, common in all methods, are: for latitude; 3.6±0.2, 6.2±0.5, 17.5±3.0 months, a sporadic one of 14.3 months and a trend of 30–35 months, for longitude; 3.9±0.14, 7.3±0.5, 15.6±2 and 19.8±2.5 months, a sporadic one of 5±1 months, and a trend of 30–40 months; for area; 16.6±4.0 and 26±4 months, and sporadic ones 15–17 months and a trend of 32±7 months, and for rotation; 4.8±0.5, 8.3±0.4, 15.2±2.3, 20±3 months, a sporadic one of 5–6 months and a trend of 30–35 months. These periodic terms form a network of periodicities overlapping one upon each other. Various tests of significance and stationarity were applied to examine the reliability and variability of the periodic components.The results of these periodic/quasi-periodic components are discussed in relation to the sunspot numbers, cometary impacts and Jovian atmospheric features.