Oct 27 – 31, 2025
Europe/Stockholm timezone

Improving the Sunspot Number and Group Number series : how and when ?

Not scheduled
1h 15m
Miklagård

Miklagård

Poster CD3 - Refining the Sunspot Number Series : challenges and benefits for the Space Climate Community CD3 - Refining the Sunspot Number Series : challenges and benefits for the Space Climate Community

Speaker

Laure Lefevre (Royal Observatory of Belgium)

Description

Efforts have been undertaken by the solar community since 2010 to revise both the Sunspot Number and the Group Number series (SN and GN). I will present our latest achievements and our plans for the near future.

First, since the last revision of SN in 2015, significant progress has been made in recovering and digitizing historical datasets, notably including the Mittheilungen from the Zürich Observatory. These recovered records enabled a new reconstruction of the SN series from 1816 to 1944 (Bhattacharya et al., 2021, 2023, 2024), and also led to several revised GN reconstructions (e.g. Svalgaard & Schatten 2016, Chatzistergos et al. 2017, Usoskin et al. 2021). Furthermore, in 2022, the WDC-SILSO team launched the FARSUN project, aiming to collect, harmonize, and centralize all available sunspot datasets into a single FAIR-compliant (Findable, Accessible, Interoperable, and Reusable) database hosted in Belgium.

Second, if we look at the modern production of the SN and GN, in 2023, the WDC-SILSO launched a project to modernize the day-to-day computation of the SN, and add the production, at the same frequency, of the GN (Belgian SUNRISE).

In summary, in the near future, by mid-2027, a historical database centralizing all available sunspot data will be put into action, and will keep being updated as new data is digitized. By the same time, WDC-SILSO will have modernized the production of SN and added the production of GN. At this time, new major versions of SN and GN will be released with complete transparency as to their construction.

Do you plan to attend in-person or online? In-person

Primary author

Laure Lefevre (Royal Observatory of Belgium)

Presentation materials

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