A New Method for Reconstructing Absolute Water Vapor Maps From Persistent Scatterer InSAR

Repeat-pass spaceborne interferometric synthetic aperture radar (InSAR) has increasingly been used to produce precipitable water vapor (PWV) maps at a high spatial resolution. Since the InSAR principle is based on building the difference between the observations at two acquisition times, a large part of the atmospheric phase is lost. Using PWV data from a global positioning system (GPS) network overlapping with the InSAR coverage or data from numerical atmospheric models and reanalysis data, a combining solution produces absolute PWV maps. The lack of dense GPS networks, the coarse spatial resolution of reanalysis data, and the inaccuracy of the models restrict the combined solution. Therefore, this article presents a new approach to reconstruct absolute PWV maps using persistent scatterer InSAR data in the presence of a single reference data point or a maximum of three. By applying this approach to Envisat InSAR data in the Dead Sea region and comparing the maps to 15 reference MERIS PWV maps, the results show an average of 92% spatial correlation, 1.2-mm absolute mean and 1.7-mm standard deviation. Sentinel-1 data as well show a strong spatial correlation (90.3%) with the model data with an average standard deviation of 1.6 mm.