Abstract
The Global Navigation Satellite Systems (GNSS) continuously broadcast radio signals at two or more frequencies in the L-band, providing extensive data for GNSS multipath reflectometry. Multi-GNSS constellations provide more signals and more tracks than individual constellations, achieving greater azimuthal coverage and more frequent retrievals. The main aim of this study is to retrieve snow depth using multi-GNSS data, analyze the multi-GNSS retrievals, and then combine them. Data of four constellations from three GNSS sites are analyzed, including the BeiDou and Galileo signals, which are rarely used to retrieve snow depth. The snow depth retrievals are estimated for signal-to-noise ratio data of each signal at first. The retrievals of individual signals from four constellations, except that of the GPS P-code signal, have no detectable inter-signal bias, thus showing the same trend describing snow depth variation. Then a multi-GNSS combination method based on robust regression is used to combine the inter-constellation inter-signal retrievals, and the multi-GNSS combined retrievals show an improvement in precision, availability, and temporal sampling. Compared to that of individual signals, it achieves about 50% improvement in precision, a smaller uncertainty, and a constant sampling interval of 6 h.
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Data availability
The GNSS data for FRDN and PRDS were provided by the International GNSS Service (IGS; https://www.igs.org). The snow depth retrievals were provided by the PBO H2O research group (https://xenon.colorado.edu/portal/). The XJJC GNSS station and ALTA snow depth record station are established and managed by both the local meteorological bureau and Chang’an University. The data of XJJC and ALTA are provided by the co-author Shuangcheng Zhang, working in Chang’an University, and co-author Lifu Wang, working in Altay meteorological bureau. Please ask the corresponding data to Shuangcheng Zhang if needed.
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Acknowledgements
This work is supported by the Fundamental Research Funds for the Central Universities (B200202015), the Jiangsu Province Surveying Mapping and Geoinformation Research Project (JSCHKY201901), and the Natural Science Foundation of Jiangsu Province (BK20190496). The authors declare that they have no conflict of interest.
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Wang, X., Zhang, S., Wang, L. et al. Analysis and combination of multi-GNSS snow depth retrievals in multipath reflectometry. GPS Solut 24, 77 (2020). https://doi.org/10.1007/s10291-020-00990-3
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DOI: https://doi.org/10.1007/s10291-020-00990-3