利用多源空间大地测量数据反演地表质量重新分布

地表质量重新分布（包括大气、海洋和内陆水）对研究全球水循环和气候变化至关重要，也是影响国际地球参考框架ITRF建立和维持的主要误差源之一。本项目拟研究利用多源空间大地测量数据（GPS/SLR/GRACE/海底压强模型）反演地表质量重新分布的理论和方法。重点突破利用主成分分析方法消除GPS监测站的技术相关误差；建立统一CM（地球质量中心）框架下的联合反演方法；利用赫尔墨特方差分量估计确定联合反演的随机模型；实现长期性地表质量重新分布和冰川均衡调整（GIA）的分离等关键问题。提供一套1～60阶的季节性和长期性表面密度球谐系数（包括地心运动）以及实测GIA系数，初步探索全球非比容海平面的变化规律,进一步挖掘空间大地测量技术（尤其是GPS）在地球物理学研究应用中的潜力。本课题可为利用空间大地测量技术研究全球质量变化提供新的思路，同时可用于ITRF原点的精化，具有重要的科学意义和研究价值。

Redistribution of surface mass (including atmosphere, ocean and continental water) is not only an important indicator of global water cycle and climate change, but also one of major error sources of ITRF (International Terrestrial Reference Frame) realization and maintainance.This project aims to provide theories and methods to inverse surface mass redistribution from multiple space-geodesy data(GPS/SLR/GRACE/OBP).Key issues for this project are as follows: remove technique-related errors from GPS station coordinates using principal component analysis (PCA) approach; develop a global inversion method in CM frame; determine stochastic model of inversion using Helmert variance component estimation; simultaneously separate long-term surface mass redistribution and glacial isostatic adjustment (GIA). Seasonal and long-term spherical harmonics coefficients of surface density from degree 1 to degree 60 and observed GIA are finally derived,and then global nonsteric sea level variations is studied. Contributions of space-geodesy techniques, especially GPS, to geophysics research is tried to be improved.This project would provide new ideas to study global mass variations by space-geodesy techniques and refine the origin of ITRF, which both have important scientific significances and research values.