An international panel of experts coordinated by the NOAA and NASA,to which the WDC-SILSO contributed, released a preliminary forecast for Solar Cycle 25 on April 5, 2019. Based on a compilation of more than 60 forecasts published by various teams using a wide range of methods, the panel reached a consensus indicating that cycle 25 will most likely peak between 2023 and 2026 at a maximum sunspot number between 95 and 130. This prediction is now given in the scale of sunspot number Version 2.
Starting from a collaboration with the NCEI (NOAA, Boulder USA), we implemented new 12-month ahead predictions based on the McNish and Lincoln method. This rather simple method is based on a single mean cycle profile and is thus of "climatology" type. It was used as a standard for many years at NOAA, and we now add it to our other more advanced Standard Curves and Combined methods, allowing direct comparisons. Likewise, we now also provide a Kalman-filter optimized version of these new ML predictions.
Today marked a triple transition for us:
- Uploading the new Sunspot Number archive files containing the daily, monthly and yearly re-calibrated sunspot numbers and the new Group Number series
- In our Web site, switching to the new "Data" pages giving access to the new files, to updated graphics and also to the past version of the Sunspot Number
- Adapting and running the entire monthly procedure to produce the provisional Sunspot Numbers for June 2015 and the associated 12-months forecast and EISN.
After completing the new data files themselves, we are now finalizing the design of the new sections in our data pages.
The preparation of the July 1st transition is progressing at high pace. Hundreds of lines of codes are adapted for the new sunspot number series and for the new array of data files. The corrections can be subtle changes in hard-coded formulae for our two 12-month forecast methods, as well as large-scale modifications in our data pipeline controlling the flux of new data to route them to the proper archive file and database.
Over the past 4 years a community effort has been carried out to revise entirely the historical sunspot number series. A good overview of the analyses and identified corrections is provided in the recent review paper:
Clette, F., Svalgaard, L., Vaquero, J.M., Cliver, E. W., "Revisiting the Sunspot Number. A 400-Year Perspective on the Solar Cycle", Space Science Reviews, Volume 186, Issue 1-4, pp. 35-103.
This is actually the first deep revision of the sunspot number since its creation By R. Wolf in 1849.
Now that we completed the definitive sunspot numbers for 2014, we can conclude that the maximum of solar cycle 24 was reached in April 2014, with a maximum of the 13-month smoothed sunspot number at 81.8. Since then, solar activity has steadily declined (monthly mean sunspot number now around 40), but remained above 70 over many months, probably indicating that the annual mean for 2014 will also mark a yearly maximum at 78.9.
Over past weeks, various upgrades took place in the backstage. We further improved the primary scripts for the sunspot number calculation. We also improved the internal data flow. The biggest transition was also the full migration from our old server, which served for the past 10 years, to the new one after a full year of cross-validation (double calculation in parallel). Although those deep changes are largely invisible to the outside world, they now put a fully new engine into our sunspot number production!
Over the past month, we already got very positive feedback about our new Web site. Like for all new Web sites, we had to fix a few initial defects but now, the web site seems to be on its tracks. Sorry for any inconvenience!
On the other hand, giving a new name to our World Data Center (WDC) seems to have caused some confusion. Will SIDC disappear? What will it change in the SIDC and sunspot services? So, let us clarify this point.