5:00 PM - 5:15 PM
[G06-2-03] Impact assessment of regional versus global Numerical Weather Model–derived tropospheric corrections for GPS and VLBI
Mapping functions based on Numerical Weather Models (NWM) have been developed in the recent years to model tropospheric delay in Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI).Their limited accuracy however, requires the estimation of residual tropospheric delay for results of high accuracy.
Correlation between the tropospheric delay, the receiver clock offset and the station height prolongs the time required for the solution to converge and impacts directly the accuracy of the results. Although observation in low elevation angles, help the parameters to de-correlate, they amplify the noise, are not always adequate and it is a highly demanding prerequisite for real-time applications.
In this study, we applied tropospheric corrections proceeding from high resolution NWM in Precise Point Positioning (PPP), in an attempt to acquire rapid and accurate positioning results, particularly useful for kinematic applications, positioning in non-standard weather conditions and obstructed environment, where estimation of tropospheric delay/height/clock offset is ambiguous.
Although regional NWM have outperformed standard atmosphere parameters and global models, it is the first time they were compared against other NWM-derived corrections; such as the state-of-art Vienna Mapping Function 1 (VMF1) parameters.
To eliminate processing systematic effects, a consistent VLBI solution was generated.
The results were assessed in terms of their formal errors, convergence time, station coordinate and baseline repeatability respectively, for the PPP and VLBI analysis.
Results shown minimal improvement in convergence time in “non-demanding" conditions, but “cm" height differences in kinematic mode and cases of tropospheric disturbances for specific sites. The quality of the corrections and the filter a-priori variance, are barometrical for the final solution.
Correlation between the tropospheric delay, the receiver clock offset and the station height prolongs the time required for the solution to converge and impacts directly the accuracy of the results. Although observation in low elevation angles, help the parameters to de-correlate, they amplify the noise, are not always adequate and it is a highly demanding prerequisite for real-time applications.
In this study, we applied tropospheric corrections proceeding from high resolution NWM in Precise Point Positioning (PPP), in an attempt to acquire rapid and accurate positioning results, particularly useful for kinematic applications, positioning in non-standard weather conditions and obstructed environment, where estimation of tropospheric delay/height/clock offset is ambiguous.
Although regional NWM have outperformed standard atmosphere parameters and global models, it is the first time they were compared against other NWM-derived corrections; such as the state-of-art Vienna Mapping Function 1 (VMF1) parameters.
To eliminate processing systematic effects, a consistent VLBI solution was generated.
The results were assessed in terms of their formal errors, convergence time, station coordinate and baseline repeatability respectively, for the PPP and VLBI analysis.
Results shown minimal improvement in convergence time in “non-demanding" conditions, but “cm" height differences in kinematic mode and cases of tropospheric disturbances for specific sites. The quality of the corrections and the filter a-priori variance, are barometrical for the final solution.