“陆态网”GPS与GRACE的中国大陆地表垂直形变对比分析

基于中国大陆构造环境监测网络的连续GPS观测数据，比较分析了中国大陆234个GPS台站和GRACE得到的地表垂直形变。GPS和GRACE垂直形变具有较好的一致性，反映了地表质量变化是引起GPS垂直形变非线性变化的重要因素之一，但二者也存在着一定的差异。为定量分析GPS和GRACE垂直形变的差异，探讨了热膨胀效应对GPS垂直位移的影响及区域地壳结构对GRACE估算地表垂直负荷形变的影响。结果表明，中国大陆50%以上的GPS台站热膨胀垂直形变周年振幅不小于1 mm；对GPS进行热膨胀效应改正后，中国大陆GPS与GRACE垂直形变具有更好的一致性；GPS与GRACE垂直形变周年振幅比值由1.07±0.06变为1.01±0.05；热膨胀效应可以解释6.2%的GPS与GRACE垂直形变的差异，热膨胀效应改正可使GPS和GRACE垂直形变的一致性相对增加11.2%。是否顾及区域地壳结构引起的GRACE估算中国大陆垂直负荷形变的相对差异为2.5%。

Comparison and Analysis of Crustal Vertical Deformation in Mainland China Observed by GPS from CMONOC and GRACE

Based on continuous GPS data from crustal movement observation network of China (CMONOC), the vertical deformations on Earth's surface observed by 234 GPS stations and GRACE in mainland China are compared with each other.GPS-observed and GRACE-derived vertical deformations are in good agreements in general, which indicates that mass loading is an important factor to GPS nonlinear variations, but there are some differences between GPS and GRACE.For further analyzing the difference between GPS and GRACE vertical deformations, we take into account the thermal expansion effects to GPS vertical deformations and the effect of regional crustal structure on vertical loading deformations derived from GRACE.It is found that the annual amplitudes of vertical deformations induced by thermal expansion are not less than 1 mm at more than 50% of GPS stations.After considering thermal deformations, the vertical deformations of GPS and GRACE are with higher consistency in mainland China.The ratio of annual amplitudes from GPS and GRACE vertical deformations changes from 1.07±0.06 to 1.01±0.05, which is closer to the ideal value of 1.Thermal expansion can explain 6.2% of the difference between GPS and GRACE vertical deformations.And it can increase the consistency of vertical deformations between GPS and GRACE by 11.2% relatively after thermal expansion correction.The regional crustal structure has little effect on GRARE-derived vertical loading deformations in mainland China and the relative difference is 2.5%.