近日，奥地利维也纳大学Mostafa Kiani Shahvandi团队报道了树木年轮记录了日长变化的水文气候波动。该研究于2026年3月12日发表于《大地测量与地球动力学》杂志上。

分析地幔自转速率变化与日长变化（ΔLOD）——即实际日长与标准86400秒之间的偏差——是地球与行星科学领域的重要课题，因为这能为全球和行星变化提供诸多关键约束。通过地幔与固态地核之间的角动量交换，气候（尤其是大气动力学）主导着年代际以下（约2-5年周期）的ΔLOD变化。虽然现代大气观测已揭示厄尔尼诺-南方涛动现象对年际ΔLOD的显著影响，但这些估算仅局限于过去几十年，阻碍了对更长时间尺度ΔLOD驱动机制的分析。

研究组首次利用公元900-2020年的树木年轮记录，以1年时间分辨率反演了ENSO驱动的ΔLOD变化。他们证实这些估算值与基于现代ENSO观测及年际大气角动量数据（1979-2020年）推算的ΔLOD具有一致性，并与古气候模式输出结果（公元900-2020年）相互印证。通过将反演的ΔLOD与天文学观测（1800-2020年）及空间大地测量数据（1962-2020年）进行对比，研究组解释了观测误差范围内相当部分的年际信号，尽管仍存在可能归因于地核顶部流体运动及其他地球物理与气候过程的重要偏差。因此，该研究表明过去1120年间ENSO很可能是年际ΔLOD的主导贡献因子，这将深化人类对行星与地幔自转的理解。

附：英文原文

Title: Tree rings record hydroclimatic fluctuations in the length of day

Author: anonymous

Issue&Volume: 2026/03/12

Abstract: Analyzing variations in the mantle’s rate of rotation and the length of day (ΔLOD)—the deviations of duration of a day from the nominal 86400 s—are important problems in Earth and planetary sciences because they provide many crucial constraints on global and planetary change. Climate, and more specifically atmospheric dynamics, dominates ΔLOD up to interannual timescales (periods of approximately 2–5 years), through exchange of angular momentum with the solid mantle. Although modern atmospheric observations have suggested the significant influence of El Nio-Southern Oscillation (ENSO) on interannual ΔLOD, these estimates are limited to the past few decades, hindering 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 (1979–2020). In addition, we reconcile our estimates with those inferred from the output of a paleoclimate model (900–2020 CE). Finally, by comparing our derived ΔLOD with the observed ΔLOD from astronomy (1800–2020) and space geodesy (1962–2020), we explain a substantial portion of the interannual signal within observational uncertainties, although there are important discrepancies that could be attributed to the fluid motion at the top of the Earth’s core and other geophysical and climatic processes. Hence, our findings show that ENSO has likely been the dominant contributor to interannual ΔLOD in the past 1120 years, which could improve our understanding of planetary and mantle rotation.

DOI: 10.1016/j.geog.2026.01.001

Source: https://www.sciencedirect.com/science/article/pii/S1674984726000212