Digitization of Sunspot Drawings by Staudacher in 1749 – 1796

Arlt, R.

doi:10.1007/s11207-007-9113-4

Cited by 82 publications

(76 citation statements)

References 4 publications

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“…There is an ongoing discussion on this topic (Krivova et al 2002;Arlt 2008;Usoskin et al 2009), so that it seems reasonable to investigate how adding a "lost" cycle 4 would affect our reconstructions.…”

Section: A "Lost Cycle"?mentioning

confidence: 99%

The solar magnetic field since 1700

Jiang

Cameron

Schmitt

et al. 2011

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We have used semi-synthetic records of emerging sunspot groups based on sunspot number data as input for a surface flux transport model to reconstruct the evolution of the large-scale solar magnetic field and the open heliospheric flux from the year 1700 onward. The statistical properties of the semi-synthetic sunspot group records reflect those of the observed Royal Greenwich Observatory photoheliographic results. These include correlations between the sunspot numbers and sunspot group latitudes, longitudes, areas and tilt angles. The reconstruction results for the total surface flux, the polar field, and the heliospheric open flux (determined by a current sheet source surface extrapolation) agree well with the available observational or empirically derived data and reconstructions. We confirm a significant positive correlation between the polar field during activity minimum periods and the strength of the subsequent sunspot cycle, which has implications for flux transport dynamo models for the solar cycle. Just prior to the Dalton minimum, at the end of the 18th century, a long cycle was followed by a weak cycle. We find that introducing a possibly "lost" cycle between 1793 and 1800 leads to a shift of the minimum of the open flux by 15 years which is inconsistent with the cosmogenic isotope record.

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Section: A "Lost Cycle"?mentioning

confidence: 99%

The solar magnetic field since 1700

Jiang

Cameron

Schmitt

et al. 2011

A&A

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“…Detailed information on sunspot locations has recently been obtained for the early past by digitizing and analysing historical sunspot drawings (Hoyt & Schatten 1992;Vaquero 2007;Arlt 2008Arlt , 2009aArlt ,b, 2011Vaquero et al 2011;Carrasco et al 2013;Casas & Vaquero 2014). This makes it possible to study, for example, the time-latitude occurrence of sunspots, such as the Maunder butterfly diagram, much further back into the past than was possible earlier.…”

Section: Introductionmentioning

confidence: 99%

Properties of sunspot cycles and hemispheric wings since the 19th century

Leussu

Usoskin

Arlt

et al. 2016

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Aims. The latitudinal evolution of sunspot emergence over the course of the solar cycle, the so-called butterfly diagram, is a fundamental property of the solar dynamo. Here we present a study of the butterfly diagram of sunspot group occurrence for cycles 7-10 and 11-23 using data from a recently digitized sunspot drawings by Samuel Heinrich Schwabe in 1825-1867, and from RGO/USAF/NOAA(SOON) compilation of sunspot groups in 1874-2015. Methods. We developed a new, robust method of hemispheric wing separation based on an analysis of long gaps in sunspot group occurrence in different latitude bands. The method makes it possible to ascribe each sunspot group to a certain wing (solar cycle and hemisphere), and separate the old and new cycle during their overlap. This allows for an improved study of solar cycles compared to the common way of separating the cycles. Results. We separated each hemispheric wing of the butterfly diagram and analysed them with respect to the number of groups appearing in each wing, their lengths, hemispheric differences, and overlaps. Conclusions. The overlaps of successive wings were found to be systematically longer in the northern hemisphere for cycles 7-10, but in the southern hemisphere for cycles 16-22. The occurrence of sunspot groups depicts a systematic long-term variation between the two hemispheres. During Schwabe time, the hemispheric asymmetry was north-dominated during cycle 9 and south-dominated during cycle 10.

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“…In regard to the GSN, the Sunspot Number Workshops drew attention to the inhomogeneity in the early RGO series responsible for the~1885 discontinuity (Svalgaard 2010;Clette et al 2014;Cliver & Ling 2016), the 1874-1976 interval used to scale GSN to WSN which was affected by both the RGO inhomogeneity and the Waldmeier discontinuity (Clette et al 2014), and the RGO-ISOON transition after 1975 (Clette et al 2014). Both series have benefitted from the important ongoing work of Vaquero, Arlt, and others (e.g., Vaquero 2007;Arlt 2008Arlt , 2009Arlt , 2011Vaquero et al 2011Vaquero et al , 2012Carrasco et al 2013;Vaquero & Gallego 2014, Diercke et al 2015Vaquero et al 2016) to both critically evaluate and increase the sunspot Hoyt & Schatten (1998a, 1998b group number database, including digitization, archival, and accessibility. In addition, have specified a constant non-linear relationship between the sunspot number and group counts.…”

Section: Discussionmentioning

confidence: 99%

“…Consider Staudacher (or Staudach; Svalgaard & Schatten 2016) -a key long-term observer during the second half of the 18th century (with 1142 observations from 1749 to 1799; Clette et al 2014). Arlt (2008) writes that, ''Nearly all of the spots [in Staudacher's drawings] show no distinction of umbra and penumbra. The size of the ink spots indicates that Staudacher included the penumbra in the spot size.…”

Section: Long-term Behavior Of the K 0 Seriesmentioning

confidence: 99%

Sunspot number recalibration: The ~1840–1920 anomaly in the observer normalization factors of the group sunspot number

Cliver¹

2017

J. Space Weather Space Clim.

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We analyze the normalization factors (k 0 -factors) used to scale secondary observers to the Royal Greenwich Observatory (RGO) reference series of the Hoyt & Schatten (1998a, 1998b group sunspot number (GSN). A time series of these k 0 -factors exhibits an anomaly from 1841 to 1920, viz., the average k 0 -factor for all observers who began reporting groups from 1841 to 1883 is 1.075 vs. 1.431 for those who began from 1884 to 1920, with a progressive rise, on average, during the latter period. The 1883-1884 break between the two subintervals occurs precisely at the point where Hoyt and Schatten began to use a complex daisy-chaining method to scale observers to RGO. The 1841-1920 anomaly implies, implausibly, that the average sunspot observer who began from 1841 to 1883 was nearly as proficient at counting groups as mid-20th century RGO (for which k 0 = 1.0 by definition) while observers beginning during the 1884-1920 period regressed in group counting capability relative to those from the earlier interval. Instead, as shown elsewhere and substantiated here, RGO group counts increased relative to those of other long-term observers from 1874 to~1915. This apparent inhomogeneity in the RGO group count series is primarily responsible for the increase in k 0 -factors from 1884 to 1920 and the suppression, by 44% on average, of the Hoyt and Schatten GSN relative to the original Wolf sunspot number (WSN) before~1885. Correcting for the early ''learning curve'' in the RGO reference series and minimizing the use of daisy-chaining rectifies the anomalous behavior of the k 0 -factor series. The resultant GSN time series (designated GSN*) is in reasonable agreement with the revised WSN (S N *; Clette & Lefèvre 2016) and the backbone-based group sunspot number (R GS ; Svalgaard & Schatten 2016) but significantly higher than other recent reconstructions (Friedli, personal communication, 2016;Lockwood et al. 2014aLockwood et al. , 2014bUsoskin et al. 2016a). This result is substantiated by a ''correction-factor'' (CF) time series defined as the ratio of annual group counts of the Hoyt & Schatten (1998a, 1998b series to the average raw (unscaled) group counts of all observers, as well as by a comparison of the GSN and GSN* time series with a recent reconstruction of solar wind B from 1845 to the present. The~1840-1920 k 0 -factor anomaly and its impact on the Hoyt and Schatten GSN are discussed in the context of the ongoing effort to recalibrate the sunspot number time series.

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Digitization of Sunspot Drawings by Staudacher in 1749 – 1796

Cited by 82 publications

References 4 publications

The solar magnetic field since 1700

The solar magnetic field since 1700

Properties of sunspot cycles and hemispheric wings since the 19th century

Sunspot number recalibration: The ~1840–1920 anomaly in the observer normalization factors of the group sunspot number

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