Results 11 to 20 of about 3,105 (240)
The lost sunspot cycle: Reanalysis of sunspot statistics [PDF]
Astronomy & Astrophysics, 2003 We have recently suggested that one low sunspot cycle was possibly lost in 1790s (Usoskin et al. 2001, A&A, 370, L31). In this paper we present the results of a rigorous statistical analysis of all available sunspot observations around the suggested additional cycle minimum in 1792-1793.
I. G. Usoskin +2 more
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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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Bistability in the sunspot cycle
Europhysics LettersAbstract A direct dynamical test of the sunspot cycle is carried out to indicate that a stochastically forced nonlinear oscillator characterizes its dynamics. The sunspot series is then decomposed into its eigen time-delay coordinates.
Vashishtha, Sumit +1 more
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The proposed “Waldmeier discontinuity”: How does it affect to sunspot cycle characteristics?
Journal of Space Weather and Space Climate, 2012 Recently, Svalgaard has proposed that Waldmeier introduced a discontinuity in the International Sunspot Number (ISN) around 1945. In this paper, we study some characteristics of the sunspot cycle using the classical ISN and the proposed version derived ...
Pérez Aparicio Alejandro Jesús +2 more
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Solar activity cycle 25: the first three years
Solar-Terrestrial Physics, 2023 We analyze features of current solar activity cycle 25 for the first three years of its development (2020–2022). Compared to cycle 24, the current cycle is shown to exceed the previous one in the number of sunspot groups (1.5 times), the number of flares
Yazev S. A. +2 more
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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
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Properties of sunspots in cycle 23 [PDF]
Astronomy & Astrophysics, 2007 In this paper we investigate the dependence of umbral core brightness, as well as the mean umbral and penumbral brightness on the phase of the solar cycle and on the size of the sunspot. Albregtsen & Maltby (1978) reported an increase in umbral core brightness from the early to the late phase of solar cycle from the analysis of 13 sunspots which ...
Mathew, S. +3 more
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, 2021 A 93-year long cycle seems to be lurking in the solar sunspot activity ...
Cusmariu, Adolf
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Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude [PDF]
, 2020 The Sun exhibits a well-observed modulation in the number of spots on its disk over a period of about 11 years. From the dawn of modern observational astronomy, sunspots have presented a challenge to understanding—their quasi-periodic variation in number,
McIntosh, Scott W. +4 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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