Global Navigation Satellite System (GNSS) tomography has proved its potential for sensing the three-dimensional (3D) distribution of atmospheric water vapor. Although the standard tomography model has improved, the geometry defect of GNSS acquisition remains a key problem and thus becomes the focus of this research. Thanks to the availability of high-resolution Moderate Resolution Imaging Spectroradiometer (MODIS) precipitable water vapor (PWV) maps, the integration of GNSS and MODIS measurements for tropospheric tomography system is introduced and discussed to address this problem. A methodology based on the node tomography model is developed to exploit the MODIS signals, which overcomes the disadvantage of the standard voxel model in combining the MODIS observations. Three experimental schemes based on MODIS data and simultaneous GNSS observations over the Xuzhou area are implemented to validate the proposed approach. The results show that the mean number of newly crossed voxels (i.e., punctured only by the MODIS signals) increases from 2 in the top layer to 24 in the first layer. Consequently, the average number of total crossed voxels is increased from 272 to 447, which highlights the contribution of the MODIS observations to pass through the empty voxels. Besides, the mean number of tomographic observation equations is enhanced by 35.71% when the MODIS signals are combined. Two-dimensional (2D) profiles of water vapor from radiosonde and 3D distributions of it from ERA5 data are considered to validate the proposed method. It is noted that when using the proposed approach, the mean root-mean-square error (RMSE) of the 2D tomographic profiles is decreased by a value of about 1.06 g/m³ and the overall accuracy of the 3D water vapor distribution is improved by 30.40%. Both the 2D and 3D validations demonstrate the satisfactory performance of the new integrated method to optimize the tomographic water vapor field.

全球导航卫星系统（GNSS）层析成像技术已证明其在感知大气水蒸气的三维（3D）分布方面具有潜力。尽管改进了标准层析成像模型，但GNSS采集的几何缺陷仍然是一个关键问题，因此成为本研究的重点。由于高分辨率中分辨率成像光谱仪（MODIS）可沉淀水蒸气（PWV）图的可用性，引入并讨论了对流层层析成像系统的GNSS和MODIS测量的集成，以解决此问题。开发了一种基于节点层析成像模型的方法来利用MODIS信号，克服了标准体素模型在组合MODIS观测值方面的缺点。实施了基于MODIS数据和同时在GNSS观测的徐州地区的三个实验方案，以验证所提出的方法。结果表明，新交叉的体素的平均数量（即仅由MODIS信号进行穿刺）从顶层的2增加到第一层的24。因此，总交叉体素的平均数量从272增加到447，这突显了MODIS观测值通过空体素的贡献。此外，当组合MODIS信号时，层析成像观察方程的平均数目增加了35.71％。考虑了来自探空仪的水蒸气的二维（2D）轮廓和来自ERA5数据的水蒸气的3D分布，以验证所提出的方法。请注意，使用建议的方法时，³和3D水蒸气分布的整体精度提高了30.40％。2D和3D验证都证明了新的集成方法优化层析X射线水蒸气场的令人满意的性能。