Use of a GPS-derived troposphere model to improve InSAR deformation estimates in the San Gabriel Valley, California

Nicolas Houlié, Gareth J. Funning, & Roland Bürgmann

Published June 7, 2016, SCEC Contribution #6263

We evaluate the potential of troposphere models derived from ground meteorological data (pressure, temperature and relative humidity) and GPS data to improve InSAR measurements and models derived from them. We test this approach on a ERS-2/ENVISAT dataset collected during a transient surface deformation episode that occurred from January to July 2005 in the San Gabriel Valley, southern California, USA. We find that the interferometric phase change observed over the corresponding period cannot be solely attributed to hydrological uplift associated with rising groundwater levels, but also includes a significant contribution from differential tropo-
spheric delay due to differing quantities of water vapour in the troposphere on the two SAR observation dates. We show that if the tropospheric phase contribution is mistakenly interpreted as range change associated with changes in groundwater storage, both the surface displacement and the groundwater storage coefficient may be overestimated by up to 30%. This method could be applied in real-time where meteorological measurements are available near one or more GPS permanent site(s).

Citation
Houlié, N., Funning, G. J., & Bürgmann, R. (2016). Use of a GPS-derived troposphere model to improve InSAR deformation estimates in the San Gabriel Valley, California. IEEE Transactions on Geoscience and Remote Sensing, 54(9), 5365-5374.