Disentangling Climatic Signals in Earth Orientation Parameters

提出了一个处于大地测量学和物理地球系统科学之间的项目，它将解决地球自转研究中的突出问题。其中心目标是在测地观测到的极移和日长变化中，揭示气候系统变率在几周到几年时间尺度上的三种主要模式的特征。该项目具体涉及马登-朱利安振荡、南方环形模式和厄尔尼诺-南方振荡，这些是根据五个现代全球大气再分析、三个无约束海洋前向模型和一个全球海洋状态估计诊断出来的，表面质量变化来自卫星重力测量观测。选择的数据集和数值实验既反映了对地球物理流体中质量再分布的准确、运动学一致的解释的追求，也反映了对大气-海洋角动量序列在广泛的时间尺度上的不确定性估计的要求。一套核心的海洋正演模拟将与现有的几十年大气再分析相结合，并作为全球角动量估计数提供给国际社会，以促进对地球定向参数中其他重要地球物理信号的新研究。

A project placed at the interface of geodesy and physical Earth system science is proposed which will attack outstanding problems in Earth rotation research. The central objective is to unravel the signatures of three leading modes of climate system variability on time scales from a few weeks to several years in geodetically observed polar motion and length-of-day changes. The project specifically addresses the Madden-Julian Oscillation, the Southern Annular Mode, and the El Niño–Southern Oscillation, as diagnosed from five modern global atmospheric reanalyses, three unconstrained ocean forward models, and a global ocean state estimate, with surface mass changes derived from satellite gravimetry observations. Chosen datasets and numerical experiments reflect both the pursuit for accurate, kinematically consistent depictions of mass redistribution in geophysical fluids and the requirement for uncertainty estimates of atmosphere-ocean angular momentum series across a wide range of time scales. A core set of ocean forward simulations will be paired with existing, multi-decadal atmospheric reanalyses and provided as global angular momentum estimates to the international community to stimulate new research on other important geophysical signals in Earth Orientation Parameters.