The paper considers various ways of calculating atmospheric phase delays to correct the interferometric phase from which the displacements of the Earth’s surface are calculated by satellite radar interferometry methods. A local empirical weather model based on empirical dependences of physical properties of the atmosphere on altitude is constructed using data from Kamchatka meteorological stations. Using this model, electromagnetic signal propagation delays are calculated. Further, the accuracy of the empirical weather model and the GACOS (Generic Atmospheric Corrections Online Service) model is estimated by comparing them with the delays calculated from the network of GNSS sites of the Kamchatka Branch of the Federal Research Center “Unified Geophysical Service” RAS in the area of the Klyuchevskaya group of volcanoes. The results show that the GACOS model, according to all criteria of accuracy, has a lower error and better matches the GNSS data at the points where the results are compared. The relative residuals of the empirical model delays range from 0 to 5.7%, while for the GACOS delays the relative residuals do not exceed 1.6%. Meanwhile, the relative residuals for the GACOS and empirical weather models are on average 0.3 and 0.9%, respectively, and the RMS errors are 0.6 and 2.3 cm. In general, at the location points of GNSS sites, a fairly good precision of calculations is obtained: the error is less than 1%, and the coefficient of determination of the dependencies of the compared models is very high and almost corresponds to the correlation coefficient equal to 1. In addition, it is obtained for 25% of the results that the empirical model outperforms the GACOS model, i.e., the delay values are closer to the delays calculated from the measurements at the GNSS sites. Since half of the weather stations and GNSS sites used to calculate the empirical weather model are local stations of the Kamchatka network that are not part of the global networks, the results obtained provide an independent assessment of the precision of corrections from the GACOS online service to the peninsula. The results of the performed study also show that the empirical atmospheric model constructed in this work provides good precision of calculations at locations of GNSS sites and their data allow one to calculate atmospheric delays for the Earth’s surface displacement fields obtained by satellite interferometry methods with a high accuracy.
Volkova et al. (Mon,) studied this question.