利用GPS和GRACE研究澳大利亚地壳垂向季节性变化  

Seasonal Variations of Vertical Crustal Motion in Australia Observed by Joint Analysis of GPS and GRACE

作　　者：汪浩 岳建平[1] 向云飞 WANG Hao;YUE Jianping;XIANG Yunfei(School of Earth Sciences and Engineering,Hohai University,Nanjing 211100,China;GNSS Research Center,Wuhan University,Wuhan 430079,China)

机构地区：[1]河海大学地球科学与工程学院,江苏南京211100 [2]武汉大学卫星导航定位技术研究中心,湖北武汉430079

出　　处：《武汉大学学报（信息科学版）》2022年第2期197-207,共11页Geomatics and Information Science of Wuhan University

基　　金：国家重点研发计划(2018YFC1508603)。

摘　　要：为探究重力场恢复与气候实验(gravity recovery and climate experiment, GRACE)卫星与全球定位系统(global positioning system, GPS)两种独立技术获取的因陆地水储量变化引起的地壳垂向季节性位移的一致性,选取澳大利亚27个GPS站点5~10 a的高程时间序列并结合GRACE同期数据反演结果进行分析。由于GRACE空间分辨率低且其反演的负荷位移对近场质量变化的敏感性远大于远场,因而所选站点GRACE反演垂向负荷位移的振幅普遍远小于GPS观测值,但均存在明显的周年变化。采用奇异谱分析(singular spectrum analysis, SSA)提取GPS与GRACE垂向位移的周年信号,振幅相差较小,各自对应的奇异谱方差贡献率分别为21.60%、34.48%,表明GRACE垂向位移的周年成分居多。与此同时,GPS与GRACE垂向位移周年项的一致性程度受地理位置的气候条件影响较大,相比于澳大利亚中西部干旱地区,北部降雨季节性明显地区GPS与GRACE振幅与相位均具有良好的一致性。另外,交叉小波变换(cross wavelet transform,XWT)发现各个站点GPS与GRACE垂向位移均呈现显著的1 a共振周期,接近1 a周期的圆域平均相位角为-74.03°~67.23°,XWT平均相关系数为0.28~0.99,均值为0.79,说明GPS与GRACE垂向位移的周年变化存在较强的正相关性。GPS高程时序去除SSA拟合周年项与GRACE反演结果后均方根值均有减小趋势,特别是在水文负荷影响较大区域,GRACE反演结果在一定程度上能够较好地解释GPS垂向位移的周年变化,使其修正GPS高程时序的周年成分具有一定的可行性,但整体修正效果不及SSA拟合的周年项。Objectives: There are obvious seasonal variations in the GPS height time series, which affect the improvement of precision and can be corrected by both mathematical modelling and geophysical mechanisms. Compared to least square fitting, singular spectrum analysis(SSA) can extract random seasonal signals effectively through signal reconstruction, which is unaffected by the assumed sinusoidal waves. According to the elastic loading theory, the gravity recovery and climate experiment(GRACE) can be used to calculate the vertical surface displacement caused by changes in terrestrial water storage.Methods: This paper mainly studies the feasibility of correcting the seasonal variations in GPS heights using SSA and GRACE inversion results. The height time series of 27 GPS stations in Australia with a time span of from 5 to 10 years were chosen and combined with GRACE simultaneous inversions.Results: Because the spatial resolutions of GRACE are coarse and the loading displacement is much more sensitive to near-field mass changes than far-field ones, the amplitudes of GRACE-inferred hydrological loading deformations are significantly smaller than GPS. The weighted root mean square(WRMS) are reduced at 22 stations after GRACE-inferred displacement corrections, and the correlation coefficients between deformations estimated by GPS and GRACE range from 0.12 to 0.78 with a mean value of 0.43, indicating that GPS and GRACE results have good consistency and correlation. SSA is used to extract the annual signals of vertical displacements derived from GPS and GRACE, and contribution rates of singular spectral variance of annual signals are21.60% and 34.48%, respectively, expressing that annual signals are the main components of GRACEinferred results. Geographical climatic conditions have a significant impact on the consistency of annual signals derived from GPS and GRACE. Compared with the arid areas in central and western Australia, the amplitude and phase of annual signals derived from GPS and GRACE are more consistent in the no

关 键 词：GPS GRACE 垂向位移 季节性变化 奇异谱分析 交叉小波变换 

分 类 号：P223[天文地球—大地测量学与测量工程]