Abstract
The multiple global navigation satellite systems (multi-GNSS) bring great opportunity for the real-time retrieval of high-quality zenith tropospheric delay (ZTD), which is a critical quality for atmospheric science and geodetic applications. In this contribution, a multi-GNSS precise point positioning (PPP) ambiguity resolution (AR) analysis approach is developed for real-time tropospheric delay retrieval. To validate the proposed multi-GNSS ZTD estimates, we collected and processed data from 30 Multi-GNSS Experiment (MGEX) stations; the resulting real-time tropospheric products are evaluated by using standard post-processed troposphere products and European Centre for Medium-Range Weather Forecasts analysis (ECMWF) data. An accuracy of 4.5 mm and 7.1 mm relative to the Center for Orbit Determination in Europe (CODE) and U.S. Naval Observatory (USNO) products is achievable for real-time tropospheric delays from multi-GNSS PPP ambiguity resolution after an initialization process of approximately 5 min. Compared to Global Positioning System (GPS) results, the accuracy of retrieved zenith tropospheric delay from multi-GNSS PPP-AR is improved by 16.7% and 31.7% with respect to USNO and CODE final products. The GNSS-derived ZTD time-series exhibits a great agreement with the ECMWF data for a long period of 30 days. The average root mean square (RMS) of the real-time zenith tropospheric delay retrieved from multi-GNSS PPP-AR is 12.5 mm with respect to ECMWF data while the accuracy of GPS-only results is 13.3 mm. Significant improvement is also achieved in terms of the initialization time of the multi-GNSS tropospheric delays, with an improvement of 50.7% compared to GPS-only fixed solutions. All these improvements demonstrate the promising prospects of the multi-GNSS PPP-AR method for time-critical meteorological applications.
Highlights
Global Positioning System (GPS) meteorology, which is an important approach used for the remote sensing of atmospheric water vapor, was first proposed by Bevis et al [1]
A new approach for real-time zenith tropospheric delay (ZTD) estimates based on multi-GNSS precise point positioning (PPP) ambiguity resolution was proposed in this paper
Considering the post-processed final Center for Orbit Determination in Europe (CODE)/U.S Naval Observatory (USNO) ZTD products and European Centre for Medium-Range Weather Forecasts analysis (ECMWF) data as the references, we evaluated the initialization time and accuracy of real-time ZTD estimates for various PPP float or fixed solutions
Summary
Global Positioning System (GPS) meteorology, which is an important approach used for the remote sensing of atmospheric water vapor, was first proposed by Bevis et al [1]. To meet different requirements of meteorological applications, GPS water vapor derived from both post-processing and near-real-time modes is assimilated into regional and global numerical weather forecast models [13,17]. The European Co-operation in the field of Scientific and Technical Research (COST) Action ES1206 “Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate (GNSS4SWEC)” is about advanced real-time tropospheric products retrieved from multi-GNSS observations [25,26]. The post-processed final tropospheric delay products of the Center for Orbit Determination in Europe (CODE) and the U.S Naval Observatory (USNO) and products from the European Centre for Medium-Range Weather Forecasts analysis (ECMWF) are utilized to validate the real-time tropospheric delay products retrieved from multi-GNSS PPP-AR. The contribution of the multi-GNSS PPP-AR method to improvements of real-time tropospheric delay retrieval is demonstrated
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