A study of Global Wind Structure Exciting the Chandler Wobble

钱德勒摆动(以下简称CW)是地球极点的一种自由摆动，在地球的自由摆动中周期最长。然而，自一百多年前发现它以来，一直没有确定它的激发源。最近，作者和合作者根据日本气象厅数值天气预报系统的全球大气分析资料进行了评估，发现其激发源是风。由于分析数据中有两种数据集(初始化数据和未初始化数据)，他们还指出了一种可能性，即评估取决于所使用的分析数据。本文利用1980-1994年ECMWF的两种再分析资料，对连续波的大气激发进行了重新评估，并再次确认风是连续波的来源。这里再次确认的风激励与最近提出的海洋激励完全相反。有趣的是，CW是由风的变化所激发的，其功率谱在CW频率附近有一个显著的峰值。此外，所使用的两个分析数据的差异对连续波激励的评估几乎没有影响，尽管它们强烈地影响了年抖动的激励值。

The Chandler wobble (hereafter CW), a free oscillation of the Earth's pole with the longest period among the Earth's free oscillations. However, its excitation source has never been identified since its discovery more than a hundred years ago. Lately, the author and collaborators have found its excitation source to be wind from its evaluations based upon global atmospheric analysis data from numerical weather prediction system of the Japan Meteorological Agency. Since there are two kinds of data setin the analysis data (initialized and un-initialized data), they also pointed out a possibility that the evaluations depend upon the analysis data used for. In this study, the author reevaluated atmospheric excitation of CW based on the two kinds of the ECMWF reanalysis data for the period of 1980-1994, and reconfirmed wind to be the CW source. The wind excitation reconfirmed here totally opposes the oceanic excitation proposed lately. Interesting is a fact that CW is excited by the wind variation with a remarkable peak at near the CW frequency in its power spectrum. Also, the differences in the used two analysis data have almost no effect on the evaluations for the CW excitation, though they strongly affect the excitatlbn for the annual wobble.