Modified atmospheric pressure extrapolation model using ERA5 for geodetic applications

Atmospheric pressure is a widely used meteorological parameter, and surface pressure at antenna height is one of the most important parameters for calculating the Global Navigation Satellite System (GNSS) tropospheric hydrostatic delay. The latter is responsible for about 90% of the total tropospheric delay, which is one of the main error sources in geodetic applications. For convenience, a standard pressure formula is commonly applied to extrapolate pressure at any height from mean sea level (MSL). The higher the antenna is, the greater the error introduced into the calculated pressure. We study the pattern between the reference pressure, interpolated from the pressure level dataset, and the pressure extrapolated from MSL by applying a standard method at the position of 320 globally distributed GNSS stations from the gridded fifth-generation European Center for Medium-range Weather Forecasts Reanalysis (ERA5) numerical dataset. We optimize the standard method by taking height and temperature into consideration and propose two modified models based on 17 years of data. The results from pressure comparison at different height intervals and respective validation for the year 2020 show that the two modified methods exhibit a 60% improvement relative to the standard method. Moreover, the precise point positioning (PPP) test in July 2020 shows a slight but global improvement in 3D coordinates and retrieved precipitable water vapor.