Abstract：InSAR is very sensitive to atmospheric delay error. The algorithm for GPSderived atmospheric delay correction to InSAR is the most effective method for InSAR atmospheric correction using external data. In order to correct the InSAR result on a pixelbypixel basis, the GPSderived corrections have to be interpolated. The traditional inverse distance weighted interpolation (IDW) can not satisty the requirment of high accuracy because the atmospheric delay variation depends not only on the distance between the interpolated value and observations, but also on height difference. Therefore, a impact factor is designed and added into the IDW and then the new one is called as improved IDW (IIDW). Finally, the experimental results from 22 GPS stations over SCIGN show that the IIDW method is better than the IDW .
