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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The intradecadal fluctuations in the length-of-day variation (dLOD) areconsidered likely to play an important role in core motions. Two intradecadaloscillations, with 5.9yr and 8.5yr periods (referred to as SYO and EYO,respectively), have been detected in previous studies. However, whether the SYOand the EYO have stable damping trends since 1962 and whether geomagnetic jerksare possible excitation sources for the SYO/EYO are still debated. In thisstudy, based on different methods and dLOD records with different time span, weshow robust evidences to prove that the SYO and the EYO have no stable dampingtrends since 1962, and we find that there is also a possible 7.6yr signal. Toprove whether it is a periodic signal, we use the optimal sequence estimationmethod to stack 35 global geomagnetic records, the results also show an 7.6yrperiodic signal which has an Y2,-2 spatial distribution, and it has a highdegree of consistent synchronicity with the 7.6yr signal in dLOD. Afterconfirming that the jerks have no special consistency with the peaks/valleys ofthe EYO/SYO, we confirm that the geomagnetic jerks seem to be related to suddenchanges in the SYO/EYO time series and their excitation series; so we finallysuggest that jerks are possible excitation sources of the SYO/EYO. Meanwhile,after using a deconvolution method, we estimate that the period P and qualityfactor Q of the SYO and the EYO are [P=5.85+/-0.06yr, Q larger than 180] and[P=8.455+/-0.17yr, Q larger than 350], respectively.

New evidences for the fluctuation characteristic of intradecadal periodic signals in length-of-day variation