He Meilin, Shen Wenbin, Pan Yuanjin, Chen Ruizhi, Ding Hao, Guo Guangyi
School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China.
State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China.
Sensors (Basel). 2017 Dec 31;18(1):99. doi: 10.3390/s18010099.
The solid Earth deforms elastically in response to variations of surface atmosphere, hydrology, and ice/glacier mass loads. Continuous geodetic observations by Global Positioning System (CGPS) stations and Gravity Recovery and Climate Experiment (GRACE) record such deformations to estimate seasonal and secular mass changes. In this paper, we present the seasonal variation of the surface mass changes and the crustal vertical deformation in the South China Block (SCB) identified by GPS and GRACE observations with records spanning from 1999 to 2016. We used 33 CGPS stations to construct a time series of coordinate changes, which are decomposed by empirical orthogonal functions (EOFs) in SCB. The average weighted root-mean-square (WRMS) reduction is 38% when we subtract GRACE-modeled vertical displacements from GPS time series. The first common mode shows clear seasonal changes, indicating seasonal surface mass re-distribution in and around the South China Block. The correlation between GRACE and GPS time series is analyzed which provides a reference for further improvement of the seasonal variation of CGPS time series. The results of the GRACE observations inversion are the surface deformations caused by the surface mass change load at a rate of about -0.4 to -0.8 mm/year, which is used to improve the long-term trend of non-tectonic loads of the GPS vertical velocity field to further explain the crustal tectonic movement in the SCB and surroundings.
固体地球会因地表大气、水文以及冰/冰川质量负荷的变化而发生弹性形变。全球定位系统（CGPS）站的连续大地测量观测以及重力恢复与气候实验（GRACE）记录了此类形变，以估算季节性和长期的质量变化。在本文中，我们展示了通过GPS和GRACE观测识别出的华南地块（SCB）1999年至2016年期间地表质量变化和地壳垂直形变的季节性变化。我们使用33个CGPS站构建了坐标变化的时间序列，并在华南地块通过经验正交函数（EOF）进行分解。当我们从GPS时间序列中减去GRACE模拟的垂直位移时，平均加权均方根（WRMS）减少了38%。第一共同模态显示出明显的季节性变化，表明华南地块及其周边存在季节性地表质量重新分布。分析了GRACE与GPS时间序列之间的相关性，为进一步改进CGPS时间序列的季节性变化提供了参考。GRACE观测反演结果是地表质量变化负荷引起的地表形变速率约为-0.4至-0.8毫米/年，用于改进GPS垂直速度场非构造负荷的长期趋势，以进一步解释华南地块及其周边的地壳构造运动。
