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

We show that the time series of sunspot-group areas has a gap, the so-calledGnevyshev gap (GG), between ascending and descending phases of the cycle andespecially so for the even-numbered cycles. For the odd cycles this gap is lessobvious, and is only a small decline after the maximum of the cycle. Weresample the cycles to have the same length of 3945 days (about 10.8 years),and show that the decline is between 1445-1567 days after the start of thecycle for the even cycles, and extending sometimes until 1725 days from thestart of the cycle. For the odd cycles the gap is a little earlier, 1332-1445days after the start of the cycles with no extension. We analyze geomagneticdisturbances for Solar Cycles 17-24 using the Dst-index, the related Dxt- andDcx-indices, and the Ap-index. In all of these time series there is a declineat the time, or somewhat after, the GG in the solar indices, and it is asdeepest between 1567-1725 days for the even cycles and between 1445-1567 daysfor the odd cycles. The averages of these indices for even cycles in theinterval 1445-1725 are 46%, 46%, 18%, and 29% smaller compared to surroundingintervals of similar length for Dst, Dxt, Dcx, and Ap, respectively. For oddcycles the averages of the Dst- and Dxt-indices between 1322-1567 days are 31%and 12% smaller than the surrounding intervals, but not smaller for theDcx-index and only 4% smaller for the Ap-index. The declines are significant atthe 99% level for both even and odd cycles of the Dst-index and for Dxt-, Dcx-and Ap-indices for even cycles. For odd cycles of the Dxt-index thesignificance is 95%, but the decline is insignificant for odd cycles of theDcx- and Ap-indices.

Comparison of geomagnetic indices during even and odd solar cycles SC17-SC24: Signatures of Gnevyshev gap in geomagnetic activity