A trend and seasonal effect analysis of zenith tropospheric delay parameter time series at IGS stations

In this study, trend and seasonal effect analysis of time series of (IGS Repro1) ZTD data between 1995-2010 reprocessed in the framework of COST Action ES1206, GNSS4SWEC were performed. 19 IGS stations were used in the study selected from Turkey and Europe. Parametric and nonparametric methods were used in trend analysis. Simple linear regression is used for parametric methods. The accuracy of the model established with this methods and the significance of the regression parameters were tested with hypothesis tests. Mann-Kendall test, Mann-Kendall Rank Correlation test, Spearman's Rho and Sen's Slope method used for nonparametric methods. The result from trend tests were compared and interpreted. Then, Run (Swed-Eisenhart) test was performed. The homogeneity of ZTD data were tested by this test. Then, a seasonal effect analysis was performed on the time series. The aim of the study, was to evaluate the advantages and disadvantages of the application different methods for both trend and seasonality analysis in ZTD time series. In this work, MATLAB programming language was used in all of the tests. Finally, we would like to acknowledge Dr. Olivier BOCK, IGN, France, for making the IWV data from IGS repro1 and ERA-Interim available. These data were prepared and quality checked in the framework of COST Action ES1206, GNSS4SWEC.