Results 231 to 240 of about 917 (261)

On the dissolution of sunspot groups

Solar Physics, 1982
The behavior of magnetic fluxes from active regions is investigated for times near sunspot disappearance. It is found that the magnetic fluxes decrease on or near the date the spot vanishes. This effect is investigated and it is concluded that it is actually due to changes in the field, rather than through dissipation of the active region fields.
StevenG. Wallenhorst, Robert Howard
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Positions of sunspot groups and solar rotation

Solar Physics, 1981
The question is studied whether the one-year solar oscillation found by V. F. Chistyakov for the years 1965–1973 can be traced in the observations of sunspots of 1874–1971 published by Greenwich Observatory. The result is negative. But the study leads to the following two conclusions: (1) The average observable centres of gravity of spot groups are ...
Jaakko Tuominen, Juhani Kyröläinen
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Sunspot Group Analysis

2023
Sunspots are tracers of the solar magnetic field and are closely linked to flaring activity on the Sun. In this report, a software package is presented which can be used to analyse the rotational and translational motions of sunspots in complex sunspot groups.
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On the disappearance of a small sunspot group

Solar Physics, 1982
The small sunspot group associated with Hale active region 17694 was observed jointly by the Mount Wilson and the Big Bear Solar Observatories, through the time of sunspot disappearance. The magnetic flux from the region was seen to decrease by about 10% per day during the observing interval.
Steven G. Wallenhorst, Kenneth P. Topka
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On the rotation rates of sunspot groups

Solar Physics, 1979
The analysis of Greenwich sunspot data for cycle No. 18 shows: (1) higher rotation rates for the southern sunspot belt than for the northern belt, (2) lower rotation rates and a tendency to a more rigid rotation for greater sunspot groups, (3) lower rotation rates and a tendency to a more rigid rotation for older sunspot groups, (4) no dependence of ...
G. Godoli, F. Mazzucconi
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The classification of sunspot groups

Solar Physics, 1990
The 3-component McIntosh classification of sunspots was introduced in 1966, adopted for interchange and publication of data in 1969, and has been used increasingly in recent years. The McIntosh classification uses a modified Zurich evolutionary sequence as its first component, class, where two of the Zurich classes are omitted and more quantitative ...
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Emergence and decay of sunspot groups

2023
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)
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The Schwabe and Gleissberg Periods in the Wolf Sunspot Numbers and the Group Sunspot Numbers

Solar Physics, 2005
Three wavelet functions: the Morlet wavelet, the Paul wavelet, and the DOG wavelet have been respectively performed on both the monthly Wolf sunspot numbers (R-z) from January 1749 to May 2004 and the monthly group sunspot numbers (R-g) from June 1795 to December 1995 to study the evolution of the Gleissberg and Schwabe periods of solar activity.
K. J. Li, P. X. Gao, T. W. Su
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Proper motions of sunspot groups

Hvar Observatory bulletin, 2003
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Woehl, Hubertus, Brajša, Roman, Kučera, Aleš, Ruždjak, Vladimir, Rybak, Jan   +4 more
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The growth and decay of sunspot groups

Solar Physics, 1992
Digitized Mount Wilson sunspot data from 1917 to 1985 are analyzed to examine the growth and decay rates of sunspot group umbral areas. These rates are distributed roughly symmetrically about a median rate of decay of a few μhemisphere day-1. Percentage area change rates average 502% day-1 for growing groups and -45% day-1 for decaying groups.
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