English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

New sunspot data composites, some of which are radically different in thecharacter of their long-term variation, are evaluated over the interval1845-2014. The method commonly used to calibrate historic sunspot data,relative to modern-day data, is "daisy-chaining", whereby calibration is passedfrom one data subset to the neighbouring one, usually using regressions of thedata subsets for the intervals of their overlap. Recent studies haveillustrated serious pitfalls in these regressions and the resulting errors canbe compounded by their repeated use as the data sequence is extended back intime. Hence the recent composite data series by Usoskin et al. (2016),$R_{UEA}$, is a very important advance because it avoids regressions,daisy-chaining and other common, but invalid, assumptions: this is achieved bycomparing the statistics of "active day" fractions to those for a singlereference dataset. We study six sunspot data series including $R_{UEA}$ and thenew "backbone" data series $R_{BB}$, recently generated by Svalgaard andSchatten (2016) by employing both regression and daisy-chaining. We show thatall six can be used with a continuity model to reproduce the main features ofthe open solar flux variation for 1845-2014, as reconstructed from geomagneticactivity data. However, some differences can be identified that are consistentwith tests using a basket of other proxies for solar magnetic fields. Usingdata from a variety of sunspot observers, we illustrate problems with themethod employed in $R_{BB}$ which cause it to increasingly overestimate sunspotnumbers going back in time and we recommend using $R_{UEA}$ because it employsmore robust procedures that avoid such problems.

An Assessment of Sunspot Number Data Composites over 1845-2014