A newly unraveled 13.6-year oscillation from GPS displacements and its potential implications for the dynamic reference frame

作     者：Hao DING Weiping JIANG 

作者机构：School of Geodesy and GeomaticsHubei Luojia LaboratoryWuhan UniversityWuhan 430079China GNSS Research CenterWuhan UniversityWuhan 430079China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2024年第67卷第10期

页      面：3204-3212页

核心收录：

学科分类：081802[工学-地球探测与信息技术] 08[工学] 081105[工学-导航、制导与控制] 0818[工学-地质资源与地质工程] 0804[工学-仪器科学与技术] 0811[工学-控制科学与工程] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos.42388102,42192533,and 42192531) the Fundamental Research Funds for the Central Universities (Grant No.2042023kfyq01) the Special Fund of Hubei Luojia Laboratory (Grant No.220100002) 

主　　题：GPS displacements Decadal changes 13.6-year oscillation Displacement model Dynamic reference frame 

摘      要：Numerous practical geodetic and geophysical applications necessitate precise measurements of GNSS displacements at the millimeter or sub-millimeter level. To attain such precision, it is imperative to identify and analyze the unidentified decadal signals inherent in the GPS displacements. In this research, we employ the optimal sequence estimation method to effectively detect an about 13.6-year oscillational signal with an excited amplitude of 3.6±1.2 mm in the U-components of the GPS displacements. It is noteworthy that this signal demonstrates a consistent spatial pattern characterized by the spherical harmonic Y_(2,-2). We conduct a comparative analysis with the 13.6-year oscillation observed in length-of-day variations(and geomagnetic records), finding that they are in reverse phase. After eliminating the Earth s external excitation sources through the utilization of two distinct in-situ hydrological records, we suggest that the 13.6-year GPS signal may come from the internal motions within the Earth. However, the specific excitation source and the detailed physical mechanism remain uncertain. Additionally, we develop a mathematical displacement model to explain the 13.6-year signal. Our findings indicate that this signal can result in displacements of up to 1.37 mm and velocity effects of 0.63 mm/yr(for U-component) at maximum. These results underscore the necessity of incorporating this 13.6-year signal into the construction and maintenance of a dynamic reference frame at the millimeter level.