10:45 AM - 12:15 PM
[STT39-P12] Comparison of the GNSS tropospheric delays from different processing tools for InSAR correction
Keywords:Tropospheric delay, Interferometric, GNSS
The increased availability of satellite SAR data, along with improved InSAR processing algorithms, has led to higher accuracy of InSAR-derived displacements. However, a major source of challenge to obtain millimeter-level accuracy is the inability to model the changes in the propagation velocity of radar microwaves in the troposphere. The state of the atmosphere is usually different when the two SAR images are acquired. As a result, additional fringes would appear in the interferograms not related to topography or deformation. Tropospheric delays cannot be ignored because they often have a similar or larger magnitude compared to the actual deformation signals.
Global Navigation Satellite System (GNSS) data has been used to estimate the tropospheric delay for InSAR correction. In particular, the Precise Point Positioning (PPP) analysis solves for the position with centimeter/millimeter accuracy along with the Zenith Tropospheric Delay (ZTD) estimation using one GNSS receiver. In this study, we compared the ZTD estimation calculated by the GNSS Earth Observation Network System (GEONET) and provided by the Geospatial Information Authority of Japan (GSI) with the ZTD estimation from other processing tools.
In the first step, we compared the ZTD estimation from two different methods, RTKLIB ZTD using the PPP-static, PPP kinematic mode, and GEONET ZTD. The preliminary result exhibited significant differences up to 7 cm, and RTKLIB ZTD tends to be lower compared to GEONET ZTD. The variability of GEONET ZTD tends to be lower than RTKLIB ZTD according to the standard deviation of the ZTDs. The comparison within RTKLIB methods, PPP-static and PPP-kinematic, shows significant differences up to 9 cm different in the mean value. For further investigation, we will expand the comparison to a wider location, including the Gipsy-X ZTD, and assess the performance on the ionospheric corrected interferogram.
Global Navigation Satellite System (GNSS) data has been used to estimate the tropospheric delay for InSAR correction. In particular, the Precise Point Positioning (PPP) analysis solves for the position with centimeter/millimeter accuracy along with the Zenith Tropospheric Delay (ZTD) estimation using one GNSS receiver. In this study, we compared the ZTD estimation calculated by the GNSS Earth Observation Network System (GEONET) and provided by the Geospatial Information Authority of Japan (GSI) with the ZTD estimation from other processing tools.
In the first step, we compared the ZTD estimation from two different methods, RTKLIB ZTD using the PPP-static, PPP kinematic mode, and GEONET ZTD. The preliminary result exhibited significant differences up to 7 cm, and RTKLIB ZTD tends to be lower compared to GEONET ZTD. The variability of GEONET ZTD tends to be lower than RTKLIB ZTD according to the standard deviation of the ZTDs. The comparison within RTKLIB methods, PPP-static and PPP-kinematic, shows significant differences up to 9 cm different in the mean value. For further investigation, we will expand the comparison to a wider location, including the Gipsy-X ZTD, and assess the performance on the ionospheric corrected interferogram.