697 citations · 1.2k across the 14 of their papers we have counts for
14 papers
The Extreme Space Weather Event of 1872 February: Sunspots, Magnetic Disturbance, and Auroral Displays
Hisashi Hayakawa, Edward W. Cliver, Frédéric Clette +19
We review observations of solar activity, geomagnetic variation, and auroral visibility for the extreme geomagnetic storm on 1872 February 4. The extreme storm (referred to here as…
The McNish and Lincoln Solar Activity Predictions: The Method and its Performance
Frédéric Clette, Shantanu Jain, Tatiana Podladchikova
The McNish and Lincoln (ML) method, introduced in 1949, was one of the first attempts to produce mid-term forecasts of solar activity, up to 12 months ahead. However, it has been p…
Is the -- Sunspot Number relation linear and stable ?
Frédéric Clette
The radio flux and the Sunspot Number are the most widely used long-term indices of solar activity. They are strongly correlated, which led to the publication of many…
Reconstruction of the Sunspot Number Source Database and the 1947 Zurich Discontinuity
Frédéric Clette, Laure Lefèvre, Sabrina Bechet +2
The recalibration of the sunspot number series, the primary long-term record of the solar cycle, requires the recovery of the entire collection of raw sunspot counts collected by t…
Scale Transfer in 1849 : Heinrich Schwabe to Rudolf Wolf
Shreya Bhattacharya, Laure Lefevre, Hisashi Hayakawa +2
The focus of this study is to reveal the reason behind a scale problem detected around 1849 in the historical version of the International Sunspot Number Series, i.e. version 1 (Le…
Hemispheric sunspot numbers 1874--2020
Astrid M. Veronig, Shantanu Jain, Tatiana Podladchikova +2
We create a continuous series of daily and monthly hemispheric sunspot numbers (HSNs) from 1874 to 2020, which will be continuously expanded in the future with the HSNs provided by…
Nonparametric monitoring of sunspot number observations: a case study
Sophie Mathieu, Laure Lefèvre, Rainer von Sachs +3
Solar activity is an important driver of long-term climate trends and must be accounted for in climate models. Unfortunately, direct measurements of this quantity over long periods…
A modern reconstruction of Carrington's observations (1853-1861)
Shreya Bhattacharya, E. T. H Teague, S. Fay +3
The focus of this article is a re-count of Richard Carrington's original sunspot observations from his book drawings (Carrington,1863) by an observer from the World data Center-SIL…
Sunspot Observations by Hisako Koyama: 1945-1996
Hisashi Hayakawa, Frédéric Clette, Toshihiro Horaguchi +4
The sunspot record is the only observational tracer of solar activity that provides a fundamental, multi-century reference. Its homogeneity has been largely maintained with a succe…
Historical astronomical data: urgent need for preservation, digitization enabling scientific exploration
Alexei Pevtsov, Elizabeth Griffin, Jonathan Grindlay +16
Over the past decades and even centuries, the astronomical community has accumulated a signif-icant heritage of recorded observations of a great many astronomical objects. Those re…
A Revised Collection of Sunspot Group Numbers
J. M. Vaquero, L. Svalgaard, V. M. S. Carrasco +7
We describe a revised collection of the number of sunspot groups from 1610 to the present. This new collection is based on the work of Hoyt and Schatten (Solar Phys. 179, 189, 1998…
Uncertainties in the Sunspot Numbers: Estimation and Implications
Thierry Dudok de Wit, Laure Lefèvre, Frédéric Clette
Sunspot number series are subject to various uncertainties, which are still poorly known. The need for their better understanding was recently highlighted by the major makeover of…
The revised Brussels-Locarno Sunspot Number (1981-2015)
Frédéric Clette, Laure Lefèvre, Marco Cagnotti +2
In 1981, the production of the international Sunspot Number moved from the Zürich Observatory to the Royal Observatory of Belgium, marking a very important transition in the histor…
Revisiting the Sunspot Number
Frédéric Clette, Leif Svalgaard, José M. Vaquero +1
Our knowledge of the long-term evolution of solar activity and of its primary modulation, the 11-year cycle, largely depends on a single direct observational record: the visual sun…