Do Records of Sunspot Sightings Provide Reliable Indicators of Solar Maxima for 1613 – 1918?
Records of Sunspot Sightings (RSS) which were obtained by the naked eye without the aid of the telescope are essential to find the solar activity in the distant past. Intense solar activity or the solar maxima had been identified by using the RSS for several decades. However, the performance of the RSS as the indicators of the solar maxima has rarely been discussed with quantitative analysis. The RSS from 1613 to 1918 are accessed as the indicators of the solar maxima, by using the time difference between each RSS and the specific solar maxima. The results have shown that about 33% of the sunspot sightings were obtained within one year of the solar maxima and about 51% of the sunspot sightings were obtained within 2 years of the solar maxima. The average time error of identifying the solar maxima by the RSS is 2.52 years, during the period 1613 – 1918. If a certain amount of time error could be tolerated for the identification of the solar maxima, the RSS could be generally used as indicators of the solar maxima.
KeywordsSolar Cycle Sunspots Sunspot number
This work gets financial supports from Natural Science Foundation of China (No. 11863001), Research Project of Education-Department in Yunnan Province (No. 2019J0400) and Research Project of Chuxiong Normal University (No. BSQD1801). The authors are very grateful for the reviewer for their professional and valuable comments that have improved the manuscript substantially. The reviewer’s work and vital contributions to this manuscript are highly appreciated by the authors. The data of the Group Sunspot Number used in here is downloaded from the website www.ngdc.noaa.gov/stp/space-weather/solar-data/solar-indices/sunspot-numbers/group/
Disclosure of Potential Conflicts of Interest
The authors indicate that they have no conflicts of interest.
- Beijing Observatory: 1988, Ancient Chinese Astronomical Records. Jiangsu Science and Technology Press, Jiangsu (In Chinese). Google Scholar
- Xu, Z.T., Jiang, Y.T., 1990, Research and Modern Applications of the Sunspots’ Records in Ancient China, Nanjing University Press, Nanjing (In Chinese). Google Scholar