北美哈德逊湾西部冰川均衡调整的InSAR监测研究

In the area west to Hudson Bay, the glacial isostatic adjustment (GIA) model ICE-5G showed that a thick ice-sheet occurred during the Last Glacier Age. However, there has been no evidence found from geodetic data. Therefore, we intend to employ InSAR techniques to obtain the GIA induced crustal motion trend, and the results together with other types of data in the North America are used to constrain the GIA model. For the InSAR techniques, considering that the GIA deformation is featured with long wavelength and slow velocity, we combine MM5 weather model(short for Fifth-Generation Penn State/NCAR Mesoscale Model) with GIM Ionosphere model(short for Global Ionosphere Maps) to establish the precise atmospheric correction model and orbital correction model for multi-sources and multi-scales; Simultaneously, based on the existing QPS InSAR, we probe into the inversion method for the time-series of deformation at a regional scale. For the study of GIA model,we combine the InSAR results with the GPS data, satellite gravity data and historic relative sealevel records in North America to constrain the GIA model. We will show the results from this model including the estimate of the ice-sheet thickness west to Hudson Bay, by which the exsiting GIA models can be efficiently evaluated, the estimate of mantle viscosity and the predictions of GIA induced crustal motion, gravity perturbation and sealevel change. The achievement from this study will be of significance for the investigation of global change, sealevel change and polar ice mass balance.

)：在哈德逊湾西部，冰川均衡调整(GIA)模型ICE-5G推测末次冰期存在巨厚的古冰盖，但一直缺少大地测量证据，为此我们尝试InSAR获取GIA形变趋势，并结合北美其它资料进行GIA模型研究。在InSAR数据处理技术方面，我们针对GIA变形具有长波长、速度缓慢的特点，融合MM5数值天气预报模型和GIM全球电离层模型，建立多源、多尺度耦合的大气改正模型和轨道误差校正模型，以有效消除InSAR观测中的长波误差源影响；同时基于现有QPS技术，研究区域尺度的时序InSAR高精度反演方法。在GIA模型研究方面，我们利用InSAR观测结果与北美GPS、卫星重力和历史海平面资料，联合约束GIA模型，将给出哈德逊湾西部的冰盖厚度估计，并据此评估现有GIA模型的结果；同时给出地幔粘滞度估计和预测GIA对地壳运动、重力场和海平面变化的影响。该课题的成果对全球变化、海平面和极地冰质量平衡研究具有重要意义。

在北美哈德逊湾西部，冰川均衡调整(GIA)模型ICE-5G推测末次冰期存在巨厚的古冰盖，但一直缺少大地测量证据，为此我们尝试InSAR获取GIA形变趋势，并结合北美其它资料进行GIA模型研究。我们在北美开展了InSAR监测GIA的试验研究，证实InSAR有较好的相干图像，并获得了变形估计，但由于在时间上和覆盖上SAR数据缺乏，不能获得GIA长期的变形，因此提出了月基InSAR解决此问题初步设想，即利用“月基”InSAR的大视角和永久观测的特点，我们成功参与了基金委“月基”重大项目课题；在GIA模型研究方面，在斯堪的纳维亚增添了GIA新的大量的GPS观测、揭示了观测对不同GIA参数的敏感性，并用历史海平面数据、GPS、卫星重力精化了横向非均匀的地幔黏滞度模型，同时给出了地幔粘滞度估计和预测GIA对地壳运动、重力场和海平面变化的影响。提出了GIA与水文信号的分离理论途径，在北美北欧进行了成功的应用。在青藏高原及其邻区的9个区域，首次用GRACE揭示了地下水增多。相关论文在Nature Geoscience， EPSL等杂志发表，产生了较好影响。该课题的成果对全球变化、海平面和极地冰质量平衡研究具有重要意义。