Single-Epoch Tropospheric Refractivity Tomography using Distributed Spaceborne D-InSAR

The three-dimensional (3-D) fine structure of the troposphere is crucial for accurate prediction of meteorological activities. Differential Interferometric Synthetic Aperture Radar (D-InSAR) has become an emerging method for tropospheric monitoring with its high resolution and wide coverage. However, a single satellites can only measure the two-dimensional (2-D) troposphere along the line-of sight direction, and only differential parameters can be inverted, making it difficult to achieve three-dimensional absolute measurements. This paper proposes a distributed spaceborne SAR system scheme, combined with external Numerical Weather Prediction (NWP) models, to recover absolute delays at a single epoch, and uses distributed multi-angle observations to achieve three-dimensional tomography of the troposphere. The experiment based on the DALES model validate the effectiveness, the inverted refractivity with resolution of sub-kilometer is consistent with the true value, with an RMSE below 20, and the RMSE of the total delay along the zenith direction is around 2mm.