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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 31 (1973), S. 23-53 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Four Mt. Wilson measurements (T〉4 h) of the photospheric motion at one point on the Sun are shown to have the characteristics of a narrow-band random process. The motion is shown to have a characteristic correlation time of 23 min and a mean power spectrum that is a smooth, single-peaked function centered at 3.4 mHz. In order to make this classification we use the analytic signal to estimate the amplitude, phase, and frequency as functions of time. The power spectrum analysis differs from the common approaches in that it uses the theoretical expression for the mean spectrum for a sequence of random pulses. Because of the random nature of the motion, we doubt the existence of more than one eigenfrequency characteristic of the photosphere as a whole. Likewise, any description of the observed motion in terms of simple deterministic functions will be inadequate for the data used here.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 31 (1973), S. 55-74 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A more objective statistical technique is applied directly to the four time series used in Paper I. The empirical probability density functions indicate that the measurements are realizations of a narrow-band random process with Gaussian statistics. This result allows quantitative statistical use of the mean autocorrelation function. For example, a characteristic correlation time is 23 min, and the motion becomes statistically uncorrelated over intervals greater than 40 min. The mean autocorrelation function is found to be free of secondary maxima that have been so troublesome in other analyses. The question raised in this paper is whether our statistical model of the motion as a Gaussian random process is also applicable to smaller regions on the order of 1″ to 2″ in size.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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