DESPECKLING POLSAR IMAGES BASED ON RELATIVE TOTAL VARIATION MODEL

We developed a high-quality and cost-effective shallow-water depth model for >120 islands in the South China Sea, using ICESat-2 and Sentinel-2 satellite data. This model accurately maps water depths with an accuracy of ~1 m. Our findings highlight the limitations of existing global bathymetry models in shallow regions. Our model exhibited superior performance in capturing fine-scale bathymetric features with unprecedented spatial resolution, providing essential data for marine applications.

Using evidence from meteorological stations, this study assessed the climatic, hydrological, and ecological aridity changes in global drylands and their associated mechanisms. A decoupling between atmospheric, hydrological, and vegetation aridity was found. This highlights the added value of using station-scale data to assess dryland change as a complement to results based on coarse-resolution reanalysis data and land surface models.

The HY-2A calibration microwave radiometer (CMR) water vapor product is validated using ground-based GNSS observations along the coastline and shipborne GNSS observations over the Indian Ocean. The validation result shows that HY-2A CMR PWV agrees well with ground-based GNSS PWV, with 2.67 mm in rms within 100 km and an RMS of 1.57 mm with shipborne GNSS for the distance threshold of 100 km. Ground-based GNSS and shipborne GNSS agree with HY-2A CMR well.

Currently, the atmospheric phase delay is one of the most critical issues in InSAR deformation monitoring. We applied the proposed GACOS-corrected InSAR stacking method in the North China Plain and analysed its performance. Deformation maps revealed by InSAR stacking with and without GACOS corrections showed that GACOS could mainly remove the topography-related and long wavelength signals.