Deciphering climatic shifts in the length of day from 1120 years of tree ring records

Deciphering climatic shifts in the length of day from 1120 years of tree ring records | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 21 July 2025 V1 Latest version Share on Deciphering climatic shifts in the length of day from 1120 years of tree ring records Author : Mostafa Kiani Shahvandi 0000-0001-5705-7014 [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.175312418.89516628/v1 210 views 172 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Climate, and more specifically atmospheric dynamics, dominates the variations in Length of Day (ΔLOD) up to interannual timescales (periods of approximately 2 to 5 years), through exchange of angular momentum with the solid mantle. Specifically, modern atmospheric observations have suggested the significant influence of El Ni˜no–Southern Oscillation (ENSO) on interannual ΔLOD. However, these estimates are limited to the past few decades (mainly since the second half of the 20th century), which hinders the analysis of mechanisms responsible for ΔLOD over longer time periods. Here, for the first time, we use tree ring records in the range 900–2020 CE to infer ENSO-driven ΔLOD, with a temporal resolution of 1 year. We demonstrate the consistency of these estimates with ΔLOD inferred from modern ENSO observations and interannual atmospheric angular momentum (for the range 1979–2020). In addition, we reconcile our estimates with those inferred from the output of a paleoclimate model (specifically, the ICON model) in the entire range 900–2020 CE. Finally, by comparing our derived ΔLOD with the astronomically-observed ΔLOD (from lunar occultation and eclipse records and focusing on the range 1800–2020), we can explain the interannual part of this observed signal within one standard deviation of the associated uncertainties, although there are considerable discrepancies that could be attributed to the fluid motion at the top of the Earth’s core (thus providing constraints for core dynamics). Our findings improve understanding of the causes and mechanisms responsible for the observed ΔLOD on interannual timescales, which is a fundamental problem in global geophysics and integral in constraining many dynamical properties of the Earth, including for climate, mantle, and core dynamics. Supplementary Material File (tree_ring_lod.pdf) Download 4.31 MB Information & Authors Information Version history V1 Version 1 21 July 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords el nino southern oscillation length of day variations paleoclimate tree ring records Authors Affiliations Mostafa Kiani Shahvandi 0000-0001-5705-7014 [email protected] View all articles by this author Metrics & Citations Metrics Article Usage 210 views 172 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Mostafa Kiani Shahvandi. Deciphering climatic shifts in the length of day from 1120 years of tree ring records. Authorea . 21 July 2025. DOI: https://doi.org/10.22541/au.175312418.89516628/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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