Atmospheric Water Vapour Retrieval with Mass-market GNSS Receivers

Due to the large spatial and temporal variability of atmospheric water vapour, traditional geodetic permanent GNSS networks are unable to provide zenith total delays (ZTDs) with a sufficient spatial resolution. Recently, several GNSS manufacturers released mass-market dual frequency GNSS receivers, that became very popular in precision agriculture applications. In Hungary more than 100 mass-market permanent GNSS receivers were installed that provide real-time GNSS observations for free.
Recently we have established a near real-time GNSS data processing system for meteorological purposes. Currently two Hungarian geodetic GNSS networks are used for ZTD estimations, and the results are provided to the EUMETNET E-GVAP program. Currently, we have established a new analysis center dedicated to mass-market receivers in the Pannonian basin. Our current study introduces the first experiences obtained by estimating ZTDs using both geodetic and mass-market receivers. The results obtained by mass market receivers are compared to the results obtained at nearby geodetic receivers. Furthermore, the results are compared to ZTDs derived from numerical weather model analysis fields.
The results show that mass-market receivers provide similar RMS to the geodetic receivers. However, some stations suffer from larger observed bias that can be explained by the low-cost dual frequency antenna having a less efficient multipath rejection compared to choke-ring geodetic antennas. Nevertheless, the results showed that mass-market GNSS receivers can be cost-effective solution for network densification and achieving higher resolution monitoring of the atmospheric water vapour.