Disentangling Climatic Signals in Earth Orientation Parameters

提出了一个将大地测量学与地球物理系统科学结合起来的项目，以解决地球自转研究中的突出问题。研究的中心目标是在几周到几年的时间尺度上，通过大地测量观测到的极地运动和日长变化，揭示气候系统变率的三种主要模式的特征。该项目特别研究了麦登-朱利安振荡、南环模和El Niño-Southern振荡，这些振荡是通过五次现代全球大气再分析、三次无约束海洋正演模型和一次全球海洋状态估计，以及卫星重力观测所得的表面质量变化诊断出来的。所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、运动学一致描述的追求，也反映了对在大范围时间尺度上大气-海洋角动量系列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多年代际大气再分析相结合，并作为全球角动量估计提供给国际社会，以刺激对地球方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.