The analysis of GPS carrier-phase time transfer (GPSCPTT) data often requires that the zenith troposphere delay (ZTD) be estimated at each site as a function of time. This is because the index of refraction of the troposphere varies rapidly. Both the ZTD values and the timetransfer values are estimated simultaneously from the GPSCPTT data. This complicates the estimation of the desired time-tra...

Tropospheric delay is one of the major error sources in GPS positioning. The delay of radio signals caused by the troposphere can range from 2 m at the zenith to 20 m at lower elevation angles. In a wide area differential system, tropospheric delays are corrected locally by users using an empirical tropospheric model, with or without meteorological observations. This can easily result in residu...

The impact of GPS Zenith Total Delay (ZTD) measurements on mesoscale weather forecasts is studied. GPS observations from a permanent European network are assimilated into the Penn State/NCAR Mesoscale Model (MM5) using its three-dimensional variational assimilation (3DVAR) system. The case study focuses on a snow storm that occurred during the period of 14-15 December 2001 over the western Medi...

Tropospheric delay is one of the major factors affecting the accuracy of electromagnetic distance measurements. To provide wide-area real-time high precision zenith tropospheric delay (ZTD), the temporal and spatial variations of ZTD with altitude were analyzed on the bases of the latest meteorological reanalysis product (ERA-Interim) provided by the European Center for Medium-Range Weather For...

To address the problems of cumbersome processes, large data, and error accumulation in calculation conventional GNSS precipitable water volume (PWV), multi-factor PWV conversion models were established using multiple linear regression fitting method. This paper analyzed correlation between zenith tropospheric delay (ZTD), surface temperature (T), atmospheric pressure (P) based on data from 38 s...