The 17-month periodicity of sunspot activity

Akioka, Maki; Kubota, Jun; Suzuki, M.; Ichimoto, Kiyoshi; Tohmura, I.

doi:10.1007/bf00148785

Cited by 32 publications

(10 citation statements)

References 7 publications

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“…In addition, during the periods of the three-fold polar magnetic field reversals which occur during some sunspot cycle maxima, the temporal separation of the zones of alternated polarity of the magnetic field on H α charts is approximately equal to 1.5-2.5 years (Waldmeier, 1973, Benevolenskaya, 1991. Similar periodicities were found in variations of radio flux on 10.7cm (Belmont et al, 1966), flares and sunspot areas (Akioka et al, 1987). The high-frequency, 2-year, component is substantially weaker than the main 22-year cycle and its intensity varies with time.…”

Section: Introductionsupporting

confidence: 69%

A Model of the Double Magnetic Cycle of the Sun

Benevolenskaya

1998

The Astrophysical Journal

106

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It has been argued that the solar magnetic cycle consists of two main periodic components: a low-frequency component (Hale's 22-year cycle) and a high-frequency component (quasi-biennial cycle). The existence of the double magnetic cycle on the Sun is confirmed using Stanford, Mount Wilson and Kitt Peak magnetograph data from 1976 to 1996 (solar cycles 21 and 22). In the frame of the Parker's dynamo theory a model of the double magnetic cycle is presented. This model is based on the idea of two dynamo sources separated in space. The first source of the dynamo action is located near the bottom of the convection zone, and the second operates near the top. The model is formulated in terms of two coupled systems of non-linear differential equations. It is demonstrated that in the case of weak interaction between the two dynamo sources the basic features of the double magnetic cycle such as existence of two component and observed temporal variations of high-frequency component can be reproduced.Comment: 6 pages, 2 figure

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Section: Introductionsupporting

confidence: 69%

A Model of the Double Magnetic Cycle of the Sun

Benevolenskaya

1998

The Astrophysical Journal

106

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“…4, we find that the 500-day period does only show in the descending phase of solar cycles. For such a period, a similarly long one (≈ 17 months) was ever noted by Ichimoto et al [27] in H-alpha flares (1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984), by Akioka et al [28] in sunspot activities (1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)) and by Oliver et al [23] in sunspot areas (cycles [12][13][14][15][16][17][18][19][20][21]. Moreover, there was another very near period at 1.3 years (or 475 days) being detected in a lot of activity indices, such as solar wind oscillations [29] , sunspot number and areas [26] .…”

Section: Temporal Variability Of Pmf Periodssupporting

confidence: 69%

Periodicities in photospheric magnetic flux

Song

Wang

2006

SCI CHINA SER G

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Magnetic field plays an important role in solar structure and activity. In principle, the determination of magnetic flux would provide the best general-purpose index of solar activity. Currently, the periodicity studies corresponding to photospheric magnetic flux (PMF) are very few possibly due to the absence of a uniform flux sequence. In this paper, by using 383 NSO/Kitt Peak magnetic synoptic charts we reconstruct a flux sequence from February 1975 to August 2003 and perform a relatively systemic periodicity analysis with two methods of the Scargle periodogram and the Morlet wavelet transform. As a result, four periods are found at around 1050, 500, 300 and 160 days. We analyze these periods' temporal variabilities in detail and discuss their respective origins briefly.

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“…Bai (1987) found an important peak at 552 days in the power spectra of major flares belonging to northern hemisphere. A significant peak of around 20 rotations (about 540 days) is found by Akioka et al (1987) in the power spectra for TA (Sum of maximum areas of sunspot groups per solar rotation) and MA (mean area of sunspot groups per solar rotations) during solar cycle 21. Özgüç and Ataç (1989) reported a peak at 564 days in the F I Hα during cycle 20 and 21 considered together.…”

Section: Discussionmentioning

confidence: 99%

The North–South Asymmetry of Soft X-RAY Flare Index During Solar Cycles 21, 22 and 23

Joshi

2004

Solar Physics

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In this paper the N−S asymmetry of the soft X-ray flare index (F ISXR) during the solar cycles 21, 22 and 23 has been analyzed. The results show the existence of a real N−S asymmetry which is strengthened during solar minimum. The slope of the regression lines fitted to the daily values of asymmetry time series has been found to be negative in all the three cycles. The yearly asymmetry curve can be fitted by a sinusoidal function with a period of eleven years. The power spectral analysis of daily asymmetry time series reveals the significant periods of around 28.26 days, 550.73 days and 3.72 years.

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The 17-month periodicity of sunspot activity

Abstract: A statistical study of sunspot activity during 1969 to 1986 was carried out by using the number of sunspot groups and their areas. We found a 17-month periodicity, which is consistent with the 500-day periodicity of flare occurrence (Ichimoto et aL, 1985).

Cited by 32 publications

References 7 publications

A Model of the Double Magnetic Cycle of the Sun

A Model of the Double Magnetic Cycle of the Sun

Periodicities in photospheric magnetic flux

The North–South Asymmetry of Soft X-RAY Flare Index During Solar Cycles 21, 22 and 23

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