title: Seasonal Mass Changes and Crustal Vertical Deformations Constrained by GPS and GRACE in Northeastern Tibet.
abstract: Surface vertical deformation includes the Earth's elastic response to mass loading on or near the surface. Continuous Global Positioning System (CGPS) stations record such deformations to estimate seasonal and secular mass changes. We used 41 CGPS stations to construct a time series of coordinate changes, which are decomposed by empirical orthogonal functions (EOFs), in northeastern Tibet. The first common mode shows clear seasonal changes, indicating seasonal surface mass re-distribution around northeastern Tibet. The GPS-derived result is then assessed in terms of the mass changes observed in northeastern Tibet. The GPS-derived common mode vertical change and the stacked Gravity Recovery and Climate Experiment (GRACE) mass change are consistent, suggesting that the seasonal surface mass variation is caused by changes in the hydrological, atmospheric and non-tidal ocean loads. The annual peak-to-peak surface mass changes derived from GPS and GRACE results show seasonal oscillations in mass loads, and the corresponding amplitudes are between 3 and 35 mm/year. There is an apparent gradually increasing gravity between 0.1 and 0.9 μGal/year in northeast Tibet. Crustal vertical deformation is determined after eliminating the surface load effects from GRACE, without considering Glacial Isostatic Adjustment (GIA) contribution. It reveals crustal uplift around northeastern Tibet from the corrected GPS vertical velocity. The unusual uplift of the Longmen Shan fault indicates tectonically sophisticated processes in northeastern Tibet.
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. pan_yuanjin@163.com.
authors.forename: Yuanjin
authors.initials: Y
authors.lastname: Pan
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. wbshen@sgg.whu.edu.cn.|State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China. wbshen@sgg.whu.edu.cn.
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Shen
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. cheinway@mail.nctu.edu.tw.|Department of Civil Engineering, National Chiao Tung University, Hsinchu 300, Taiwan. cheinway@mail.nctu.edu.tw.
authors.forename: Cheinway
authors.initials: C
authors.lastname: Hwang
authors.affiliation: School of Land Resources and Surveying, Guangxi Teachers Education University, Nanning 530001, China. gps94041@163.com.
authors.forename: Chaoming
authors.initials: C
authors.lastname: Liao
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. txzhang521@163.com.
authors.forename: Tengxu
authors.initials: T
authors.lastname: Zhang
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. gqzhangsgg@whu.edu.cn.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Zhang
keywords: CGPS time series; GRACE observations and surface loads; crustal vertical deformation; empirical orthogonal function