Spectrum analysis of Jupiter's great red spot parameters: area, rotation, latitude and longitude (1963-67)

Spectrum analysis of Jupiter's great red spot area, rotation, longitude, an d latitude, for the period 1963-1967, has been performed. The methods of ma ximum entropy, power spectrum (Blackman-Tukey approach), Fourier, and autoc orrelation have been employed to detect periodicities in the variation of t hese parameters. The method of 'successive approximations' was applied to t he area time-series, and periods of 25, 16, 5 and 3 months and a trend simi lar to 32 months were identified and an analytical expression fit was given , with an accuracy of 78%. Only some periods (6-18 months) describe the mai n trends of the variation, the shorter (2-5 months) exhibit a stochastic va riability, while the longer ones which approach the total record represent a trend. The obtained significant periods and long term trends, common in a ll methods, are: for latitude; 3.6 +/- 0.2, 6.2 +/- 0.5, 17.5 +/- 3.0 month s, 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 30-0 months; for area; 16.6+/-4.0 an d 26+/-4 months, and sporadic ones 15-17 months and a trend of 32 +/- 7 mon ths, 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. Vari ous tests of significance and stationarity were applied to examine the reli ability and variability of the periodic components. The results of these pe riodic/quasi-periodic components are discussed in relation to the sunspot n umbers, cometary impacts and Jovian atmospheric features. (C) 1999 Publishe d by Elsevier Science Ltd. All rights reserved.