A Double Differencing Algorithm for GPS-derived Tropospheric Delay Corrections to Differential Radar Interferometry

Tropospheric heterogeneity can lead to misinterpretation of differential radar interferometric results. A betweensite and between-epoch double-differencing algorithm for the derivation of tropospheric corrections to radar results using GPS measurements is proposed. In order to correct the radar result on a pixel-by-pixel basis, the GPS-derived corrections have to be interpolated. Using the GPS data from the SCIGN network it has been found that the inverse distance weighted and Kriging interpolation methods are more suitable than the spline method. Differential corrections as much as several centimetres may have to be applied in order to ensure sub-cm accuracy for the radar result and it seems optimal to estimate from GPS data the tropospheric delay at 5 minute intervals. The algorithm and procedures described in this paper could be easily implemented in a CGPS data centre. The interpolated image of between-site, single-differenced tropospheric delay can be provided as a routine product to assist radar interferometry.