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A relationship between the solar rotation and activity in the period 1998–2006 analysed by tracing small bright coronal structures in SOHO-EIT images

“…For the investigation of possible variations in the solar rotation, the Greenwich data set was used by Balthasar & Wöhl (1980), Arévalo et al (1982), and Balthasar et al (1986); the Kanzelhöhe data set by Lustig (1983); the Mt. Wilson data set by Gilman & Howard (1984) and by Hathaway & Wilson (1990); the Mitaka data set by Kambry & Nishikawa (1990); the Suzuka data set by Suzuki (1998); the extended Greenwich data set by Pulkkinen & Tuominen (1998), Javaraiah (2003), Zuccarello & Zappalá (2003), Javaraiah et al (2005), Javaraiah & Ulrich (2006), and Brajša et al (2006Brajša et al ( , 2007; the Kodaikanal data set by Gupta et al (1999); and the Abastumani data set by Khutsishvili et al (2002). Also, temporal variations in the solar rotation were studied using other Article published by EDP Sciences A17, page 1 of 6…”

Internal-Cycle Variation of Solar Differential Rotation

“…Rotation taken by Suzuki (1998Suzuki ( , 2012 Daily photographic observations of sunspots at the solar full disk have been made with a refractor of 102 mm aperture and 1200 mm focal length by Suzuki since the year of 1988, and the positions of sunspot groups at the solar disk are obtained (Suzuki 1998(Suzuki , 2012. He measured annual mean rotation rates of sunspots in 5 0 latitude bin during cycles 22 to 23 (from 1998 to 2006) through analyzing his observational data of sunspots.…”

“…In this study, we will investigate internal-cycle variation of solar differential rotation, using the measurements of rotation rates made by Suzuki (1998Suzuki ( , 2012 and Pulkkinen & Tuominen (1998a). A new explanation is proposed to address such a solar-cycle related variation of the solar rotation rates.…”

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Abstrct. The latitudinal distributions of the yearly mean rotation rates measured respectively by Suzuki in 1998 and Pulkkinen & Tuominen in 1998 are utilized to investigate internal-cycle variation of solar differential rotation. The rotation rate at the solar Equator seems to decrease since cycle 10 onwards.

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What causes the 24-day period observed in solar flares?

“…However, from solar rotation studies based on tracing sunspots only a small fraction (of the order of 1%) of sunspots is reported with sidereal velocities as high as 16 deg/day corresponding to a ∼24-day synodic period (e.g. Godoli et al 1998;Pulkkinen & Tuominen 1998;Suzuki 1998).…”