The Sidc: World Data Center for the Sunspot Index

Vanlommel, Petra; Cugnon, P.; Linden, R. A. M. Van der; Berghmans, D.; Clette, Frédéric

doi:10.1007/s11207-005-6504-2

Cited by 36 publications

(26 citation statements)

References 1 publication

(1 reference statement)

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“…Typical value of this factor is between 0.4 and 1.7, and each observatory is supposed to show self-consistent values. For example, the correction factor of the Locarno Observatory as the reference station is 0.6 to the old value of Wolf (Vanlommel et al 2004). This means that the sunspot numbers recorded by Wolf are systematically 0.6 times smaller than those observed and recorded at the Locarno Observatory.…”

Section: Introductionmentioning

confidence: 89%

“…It is essential for an observatory to keep their correction factor constant in order to secure a high quality of data. Considering the correction factors, it seems that the current sunspot numbers recorded by the SIDC have no systematic error compared to the Zürich numbers (Vanlommel et al 2004, Berghmans et al 2006, Clette et al 2007). Third, they are expanding their efforts of collecting more data sets to as many regions throughout the world as possible, out from the supplementary stations mostly located in Europe and some parts in Asia.…”

Section: Introductionmentioning

confidence: 94%

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Relative Sunspot Number Observed from 2002 to 2011 at ButterStar Observatory

Oh¹,

Chang²

2012

Journal of Astronomy and Space Sciences

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The ButterStar Observatory at the Dongducheon High School has been working for photographic observations of the Sun since October 16, 2002. In this study, we observed the Sun at the ButterStar observatory for 3,364 days from October 16, 2002 to December 31, 2011, and analyzed the photographic sunspot data obtained in 1,965 days. The correction factor K b for the entire observing period is 0.9519, which is calculated using the linear least square method to the relationship between the daily sunspot number, R B , and the daily international relative sunspot number, R i . The yearly correction factor calculated for each year varies slightly from year to year and shows a trend to change along the solar cycle. The correction factor is larger during the solar maxima and smaller during the solar minima in general. This implies that the discrepancy between a relative sunspot number, R, and the daily international relative sunspot number, R i , can be reduced by using a yearly correction factor. From 2002 to 2008 in solar cycle 23, 35.4% and 64.6% of sunspot groups and 35.1% and 64.9% of isolated sunspots in average occurred in the northern hemisphere and in the southern hemisphere, respectively, and from 2008 to 2011 in solar cycle 24, 61.3% and 38.7% of sunspot groups and 65.0% and 35.0% of isolated sunspots were observed, respectively. This result shows that the occurrence frequency for each type of sunspot group changes along the solar cycle development, which can be interpreted as the emerging and decaying process of sunspot groups is different depending on the phase of solar cycle. Therefore, it is considered that a following study would contribute to the efforts to understand the dependence of the dynamo mechanism on the phase of solar cycle.

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Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 94%

Relative Sunspot Number Observed from 2002 to 2011 at ButterStar Observatory

Oh¹,

Chang²

2012

Journal of Astronomy and Space Sciences

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“…Vanlommel et al 2005). This index is based on a statistical processing of the data from a worldwide network of 86 observatories from 29 countries (Clette et al 2007).…”

Section: Ionospheric Datamentioning

confidence: 99%

The influence of space weather on ionospheric total electron content during the 23rd solar cycle

Bergeot

Tsagouri

Bruyninx

et al. 2013

J. Space Weather Space Clim.

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This paper presents a new empirical model for predicting the daily mean ionospheric Total Electron Content (TEC) at a given latitude from only one solar index as input. For the development of the model we take advantage of the availability of 15 years of global GNSS-based TEC information and solar indices (Sunspot Number, F10.7 and derived F10.7P) including the 23rd solar cycle. Among all the tests, our preferred ionospheric climatological model to predict daily mean TEC presents yearly median differences with observed values of 1.4 ± 0.9 TECu (11.5 ± 2.9% for the relative differences) with no significant degradation during the different phases of the solar cycle. To realize this empirical model we used a least-square adjustment with (1) a combination of linear, annual and semi-annual terms between the TEC and F10.7P; (2) a discretization with respect to the phases of the solar cycle. The main differences between the modelled and the observed TEC occur during identified geomagnetic storms: the maximum differences (À3.2 ± 1.5 TECu) and relative differences (À19.6 ± 15.0%) occur one day after the storm onset. The typical time to retrieve the pre-storm conditions is 3-4 days after the onset. These results show a global picture of the effect of extreme Space Weather events on the Earth's upper atmosphere.

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“…5), which are obtained from the Solar Influences Data analysis Center (SIDC) 3 , Royal Observatory of Belgium (Clette et al 2007;Vanlommel et al 2004). The variation of the spot coverage with time is much easier to visualize in a graph.…”

Section: Butterfly Diagram and Relative Sunspot Numbermentioning

confidence: 99%

Digitization of sunspot drawings by Spörer made in 1861–1894

2015

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-history and philosophy of astronomy Most of our knowledge about the Sun's activity cycle arises from sunspot observations over the last centuries since telescopes have been used for astronomy. The German astronomer Gustav Spörer observed almost daily the Sun from 1861 until the beginning of 1894 and assembled a 33-year collection of sunspot data covering a total of 445 solar rotation periods. These sunspot drawings were carefully placed on an equidistant grid of heliographic longitude and latitude for each rotation period, which were then copied to copper plates for a lithographic reproduction of the drawings in astronomical journals. In this article, we describe in detail the process of capturing these data as digital images, correcting for various effects of the aging print materials, and preparing the data for contemporary scientific analysis based on advanced image processing techniques. With the processed data we create a butterfly diagram aggregating sunspot areas, and we present methods to measure the size of sunspots (umbra and penumbra) and to determine tilt angles of active regions. A probability density function of the sunspot area is computed, which conforms to contemporary data after rescaling.

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The Sidc: World Data Center for the Sunspot Index

Cited by 36 publications

References 1 publication

Relative Sunspot Number Observed from 2002 to 2011 at ButterStar Observatory

Relative Sunspot Number Observed from 2002 to 2011 at ButterStar Observatory

The influence of space weather on ionospheric total electron content during the 23rd solar cycle

Digitization of sunspot drawings by Spörer made in 1861–1894

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