The rotational spectrum of g-modes in the sun

Wolff, Charles L.

doi:10.1086/160640

Cited by 83 publications

(53 citation statements)

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“…Formulae (13) and (15) substantiate the empirical notion of subharmonics (Bai & Sturrock 1991, 1993Sturrock & Bai 1992) without involving beat frequencies or echo processes (Wol † 1983(Wol † , 1996(Wol † , 1998. We now o †er some physical considerations as to why equatorially trapped Rossby-type waves might grossly modulate solar Ñare activity and sunspot areas or groups.…”

Section: Discussionmentioning

confidence: 57%

Rossby‐Type Wave–Induced Periodicities in Flare Activities and Sunspot Areas or Groups during Solar Maxima

Lou

2000

ApJ

122

134

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The Gamma-Ray Spectrometer (GRS) aboard the Solar Maximum Mission (SMM) discovered a 154 day periodicity in solar Ñare rates. Subsequently, periodicities in various solar Ñare activities and in sunspot areas or groups during a few years around solar maxima have been extensively monitored using di †erent diagnostics and at many electromagnetic wavelengths. Notable periods are D154, 128, 102, 78, and 51 days during maxima of di †erent solar cycles from various data sets. The origin of such quasi periodicities particularly prominent during solar maxima has remained a mystery for nearly two decades. For slow and large-scale photospheric motions, the shallow magnetoÑuid approximation may be invoked when the Rossby number is small, where U cm s~1) and

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Section: Discussionmentioning

confidence: 57%

Rossby‐Type Wave–Induced Periodicities in Flare Activities and Sunspot Areas or Groups during Solar Maxima

Lou

2000

ApJ

122

134

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“…Although most of these periodicities were reported earlier in several solar activity indicators (e.g. Wolff 1983;Rieger et al 1984;Delache et al 1985;Lean & Brueckner 1989;Pap et al 1990;Bai & Sturrock 1991;Bai 2003b;Lou et al 2003), it is the first time that they have collectively been detected in direct observations of the photospheric magnetic field. The Rieger period around 155 d is of special interest and will be discussed in detail in Sect.…”

Section: Fig 1 A)mentioning

confidence: 85%

“…Let us here briefly summarize some of the relevant results. Periods near 320 d were found in the Zurich sunspot number from 1749 to 1979 (Wolff 1983), in solar diameter measurements from 1975 to 1983 (Delache et al 1985), in the sunspot blocking function, 10.7 cm radio flux, sunspot number, and plage index (but only during cycle 21, cf. Lean & Brueckner 1989), in sunspot areas and sunspot numbers (Oliver et al 1992), and also in the north-south asymmetry of sunspot areas during several solar activity minima (Paper I).…”

Section: Rieger-type Periodicitiesmentioning

confidence: 95%

Evolution and rotation of large-scale photospheric magnetic fields of the Sun during cycles 21–23

Knaack¹,

Stenflo

Berdyugina

2005

A&A

120

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Abstract. We present the results of an extensive time series analysis of longitudinally-averaged synoptic maps, recorded at the National Solar Observatory (NSO/Kitt Peak) from 1975 to 2003, and provide evidence for a multitude of quasi-periodic oscillations in the photospheric magnetic field of the Sun. In the low frequency range, we have located the sources of the 3.6 yr, 1.8 yr, and 1.5 yr periodicities that were previously detected in the north-south asymmetry of the unsigned photospheric flux (Knaack et al. 2004, A&A, 418, L17). In addition, quasi-periodicities around 2.6 yr and 1.3 yr have been found. The 1.3 yr period is most likely related to large-scale magnetic surges toward the poles and appeared in both hemispheres at intermediate latitudes ∼30• -55• during the maxima of all three cycles 21-23, being particularly pronounced during cycle 22. Periods near

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“…Wolff (1983) linked such periodicities to the interaction of rotating features (active longitude bands) resulting from g-modes with l = 2 and l = 3. Oliver et al (1998) and Ballester et al (1999) proposed a scenario in which the quasi-periodic emergence of magnetic flux can trigger solar flares (via magnetic reconnection between old and new magnetic flux present in active regions).…”

Section: Discussionmentioning

confidence: 99%

Periodicities in the X-Ray Emission From the Solar Corona

Chowdhury

Jain

Awasthi

2013

ApJ

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We have studied the time series of full disk integrated soft and hard X-ray emission from the solar corona during 2004 January to 2008 December, covering the entire descending phase of solar cycle 23 from a global point of view. We employ the daily X-ray index derived from 1 s cadence X-ray observations from the Si and CZT detectors of the "Solar X-ray Spectrometer" mission in seven different energy bands ranging between 6 and 56 keV. X-ray data in the energy bands 6-7, 7-10, 10-20, and 4-25 keV from the Si detector are considered, while 10-20, 20-30, and 30-56 keV high energy observations are taken from the CZT detector. The daily time series is subjected to power spectrum analysis after appropriate correction for noise. The Lomb-Scargle periodogram technique has shown prominent periods of ∼13.5 days, ∼27 days, and a near-Rieger period of ∼181 days and ∼1.24 yr in all energy bands. In addition to this, other periods like ∼31, ∼48, ∼57, ∼76, ∼96, ∼130, ∼227, and ∼303 days are also detected in different energy bands. We discuss our results in light of previous observations and existing numerical models.

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The rotational spectrum of g-modes in the sun

Cited by 83 publications

References 0 publications

Rossby‐Type Wave–Induced Periodicities in Flare Activities and Sunspot Areas or Groups during Solar Maxima

Rossby‐Type Wave–Induced Periodicities in Flare Activities and Sunspot Areas or Groups during Solar Maxima

Evolution and rotation of large-scale photospheric magnetic fields of the Sun during cycles 21–23

Periodicities in the X-Ray Emission From the Solar Corona

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