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Principal component analysis of sunspot cycle shape [PDF]
Astronomy & Astrophysics, 2018 Aims. We study the shape of sunspot cycles using the Wolf sunspot numbers and group sunspot numbers of solar cycles 1–23. We determine the most typical “model” cycles and the most asymmetric cycles, and test the validity of the two Waldmeier rules: the ...
J. Takalo, K. Mursula
semanticscholar +1 more source
Change of Sunspot Groups Observed from 2002 to 2011 at ButterStar Observatory [PDF]
Journal of Astronomy and Space Sciences, 2012 Since the development of surface magnetic features should reflect the evolution of the solar magnetic field in the deep interior of the Sun, it is crucial to study properties of sunspots and sunspot groups to understand the physical processes working ...
Sung-Jin Oh, Heon-Young Chang
doaj +1 more source
Sunspot Number Second Differences as a Precursor of the Following 11-year Sunspot Cycle [PDF]
, 2017 Forecasting the strength of the sunspot cycle is highly important for many space weather applications. Our previous studies have shown the importance of sunspot number variability in the declining phase of the current 11-year sunspot cycle to predict the
T. Podladchikova +2 more
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Asymmetry in Solar Torsional Oscillation and the Sunspot Cycle [PDF]
Proceedings of the International Astronomical Union, 2018 Solar torsional oscillations are migrating bands of slower- and faster-than-average rotation, which are strongly related to the Sun’s magnetic cycle. We perform a long-term study (16 yr) of hemispherical asymmetry in solar torsional oscillation velocity ...
L. B, D. Nandy, H. M. Antia
semanticscholar +1 more source
A solar cycle lost in 1793--1800: Early sunspot observations resolve the old mystery [PDF]
, 2009 Because of the lack of reliable sunspot observation, the quality of sunspot number series is poor in the late 18th century, leading to the abnormally long solar cycle (1784--1799) before the Dalton minimum. Using the newly recovered solar drawings by the
Charbonneau +12 more
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Frequency of Solar Spotless Days and Flare Index as Indices of Solar Cycle Activity [PDF]
Journal of Astronomy and Space Sciences, 2014 There was a research on the prolongation of solar cycle 23 by the solar cyclic variation of solar, interplanetary geomagnetic parameters by Oh & Kim (2013).
Suyeon Oh
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Long-term variation in distribution of sunspot groups [PDF]
, 2004 We studied the relation between the distribution of sunspot groups and the Gleissberg cycle. As the magnetic field is related to the area of the sunspot groups, we used area-weighted sunspot group data. On the one hand, we confirm the previously reported
B. Major +13 more
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Prediction of Sunspot Cycles by Data Assimilation Method [PDF]
, 2008 Despite the known general properties of the solar cycles, a reliable forecast of the 11-year sunspot number variations is still a problem. The difficulties are caused by the apparent chaotic behavior of the sunspot numbers from cycle to cycle and by the ...
Kitiashvili, I. N., Kosovichev, A. G.
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Long-term Evolution of Sunspot Magnetic Fields [PDF]
, 2010 Independent of the normal solar cycle, a decrease in the sunspot magnetic field strength has been observed using the Zeeman-split 1564.8nm Fe I spectral line at the NSO Kitt Peak McMath-Pierce telescope.
Livingston, William, Penn, Matthew
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An upper limit prediction of the peak sunspot number for solar cycle 24
Journal of Space Weather and Space Climate, 2011 In this paper we address the prediction of the maximum sunspot number in solar cycle 24. We correlate the integral sunspot activity related to the variability of the cycle decrease speed in the declining phase with the height of the next sunspot maximum.
Van der Linden R., Podladchikova T.
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