Hemispheric sunspot numbers 1874–2020

  title={Hemispheric sunspot numbers 1874–2020},
  author={Astrid M. Veronig and Shantanu Jain and Tatiana Podladchikova and Werner Poetzi and Fr{\'e}d{\'e}ric Clette},
  journal={Astronomy \& Astrophysics},
Context. Previous studies show significant north–south asymmetries for various features and indicators of solar activity. These findings suggest some decoupling between the two hemispheres over the solar cycle evolution, which is in agreement with dynamo theories. For the most important solar activity index, the sunspot numbers, so far only limited data are available for the two hemispheres independently. Aims. The aim of this study is to create a continuous series of daily and monthly… 

Hemispheric Sunspot Number from the Madrid Astronomical Observatory for the Period 1935–1986

Long-term studies on hemispheric asymmetry can help to understand better the solar dynamo. We present the hemispheric sunspot number calculated from daily sunspot observations made at the Madrid

Temporal Evolutions and Quasiperiodic Variations Present in the Sunspot Number and Group Sunspot Area Data Measured at Kodaikanal Observatory for Solar Cycles 14–24

The Kodaikanal Observatory has made synoptic observations of the Sun in white light since 1904, and these images are sketched on the Stonyhurst grids called Sun charts. These continuous hand-drawn

Evaluation of the Annual Correlations between Different Solar-Ionospheric Indices During Solar Cycles 23 and 24

     In this work, the annual behavior and cross-correlation between three different solar-ionospheric indices were evaluated: Smoothed Sunspot Number (SSN), Ionospheric T-Index (T-index), and Solar

A Sunspot Catalog by Rafael Carrasco at the Madrid Astronomical Observatory for the Period 1931 – 1933

A sunspot catalog was published by the Madrid Astronomical Observatory from sunspot observations made by Rafael Carrasco and his assistants for the period November 1931 – December 1933. We have

Full-disc Ca ii K observations—A window to past solar magnetism

Full-disc observations of the Sun in the Ca ii K  line provide one of the longest collections of solar data. First such observations were made in 1892 and since then various sites around the world

Relationship between geomagnetic storms and occurrence of ionospheric irregularities in the west sector of Africa during the peak of the 24th solar cycle

The study of ionospheric irregularities is important since many technological systems might be influenced by the ionosphere. In this work, we use data from the Global Navigation Satellite Systems

Solar-Cycle Variability Results from the Solar Radiation and Climate Experiment (SORCE) Mission

The Solar Radiation and Climate Experiment (SORCE) was a NASA mission that operated from 2003 to 2020 to provide key climate-monitoring measurements of total solar irradiance (TSI) and solar spectral

Deciphering Solar Magnetic Activity: The Solar Cycle Clock

The Sun’s variability is controlled by the progression and interaction of the magnetized systems that form the 22-year magnetic activity cycle (the “Hale Cycle”) as they march from their origin at

Kanzelhöhe Observatory: Instruments, Data Processing and Data Products

This article describes the separate processing steps from data acquisition to high level products for different observing wavelengths, and presents in detail the quality classification, which is important for further processing of the raw images.

Evolution of the Correlation Between the Amplitude of the Solar Cycle and the Sunspot Number Since the Previous Declining Phase in Both Hemispheres

  • Z. Du
  • Materials Science
    Solar Physics
  • 2022
Analyzing the variation in the correlation between the maximum amplitude [Rmax\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb}



Hemispheric sunspot numbers R~n and R~s from 1945-2004: catalogue and N-S asymmetry analysis for solar cycles 18-23

From sunspot drawings provided by the Kanzelhohe Solar Observatory, Austria, and the Skalnate Pleso Observatory, Slovak Republic, we extracted a data catalogue of hemispheric Sunspot Numbers covering


Solar magnetic activity varies with time in the two hemispheres in different ways. The hemispheric interconnection of solar activity phenomena provides an important clue to understanding the

Analysis of the Hemispheric Sunspot Number Time Series for the Solar Cycles 18 to 24

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Solar-Cycle Characteristics Examined in Separate Hemispheres: Phase, Gnevyshev Gap, and Length of Minimum

According to research results from solar-dynamo models, the northern and southern hemispheres may evolve separately throughout the solar cycle. The observed phase lag between the northern and

Active longitudes in sunspot activity: Century scale persistence

A novel analysis of sunspot group data for the past 120 years reveals that sunspots in both northern and southern hemispheres are formed preferably in two persistent active longitudes separated by

Hemispheric Coupling: Comparing Dynamo Simulations and Observations

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Revisiting the Sunspot Number

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 sunspot counts that

70 Years of Sunspot Observations at the Kanzelhöhe Observatory: Systematic Study of Parameters Affecting the Derivation of the Relative Sunspot Number

The Kanzelhöhe Observatory (KSO) was founded during World War II by the Deutsche Luftwaffe (German Airforce) as one station of a network of observatories that were set up to provide information on

Investigation of the Hemispheric Asymmetry in Solar Flare Index During Solar Cycle 21 – 24 from the Kandilli Observatory

The hemispheric asymmetry of the solar-flare index during 1976 – 2018 from the Kandilli Observatory is studied in this investigation. The temporal duration covers Solar Cycles 21 – 23 and almost the

Hemispheric Sunspot Numbers R_n and R_s: Catalogue and N-S asymmetry analysis

Sunspot drawings are provided on a regular basis at the Kanzelhoehe Solar Observatory, Austria, and the derived relative sunspot numbers are reported to the Sunspot Index Data Center in Brussels.