On the short-term temporal variations of GNSS receiver differential phase biases

Abstract

Abstract. As a first step towards studying the ionosphere with the Global Navigation Satellite System (GNSS), leveling the phase to the code geometry-free observations on an arc-by-arc basis yields the ionospheric observables, interpreted as a combination of slant total electron content along with satellite and receiver Differential Code Biases (DCB). The leveling errors in the ionospheric observables may arise during this procedure, which, according to previous studies by other researchers, are due to the combined effects of the code multipath and the intra-day variability in the receiver DCB. In this paper we further identify the short-term temporal variations of receiver Differential Phase Biases (DPB) as another possible cause of leveling errors. Our investigation starts by the development of a method to epoch-wise estimate Between-Receiver DPB (BR-DPB) employing (inter-receiver) single-differenced, phase-only 2GNSS observations collected from a pair of receivers creating a zero or short baseline. The key issue for this method is to get rid of the possible discontinuities in the epoch-wise BR-DPB estimates, occurring when satellite assigned as pivot changes. Our numerical tests, carried out using GPS (Global Positioning System, US GNSS) and BDS (BeiDou Navigation Satellite System, Chinese GNSS) observations sampled every 30 seconds by a dedicatedly selected set of zero and short baselines, suggest two major findings. First, epoch-wise BR-DPB estimates can exhibit remarkable variability over a rather short period of time (e.g. 6 centimeters over 3 hours), thus significant from a statistical point of view. Second, a dominant factor driving this variability is the changes of ambient temperature, instead of the un-modelled phase multipath.

The Impacts of the Ionospheric Observable and Mathematical Model on the Global Ionosphere Model

“…The single-difference STEC from the RP4 observable is noisier, with a peak-to-peak value of almost 18.08 TECUs, indicating the observation error of the RP4 observable is about 18.08/ √ 2 2 ≈ 6.39 TECUs. Thus, the RP4 observable has the lowest accuracy, which is one to two orders of magnitude worse than the FL4 observable.…”

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“…Different from the relative positioning strategy commonly used by many GPS‐PWV retrieval systems, the precise point positioning (PPP) technique has the advantages of low computational burden, high computational efficiency, and nonsynchronous observations requirements [ Shi et al ., ; Zumberge et al ., ]. Therefore, PPP has become a promising technique for efficient GNSS meteorology, especially with the emergence of increasingly dense GPS networks for use in regional applications [ Dousa and Vaclavovic , ; Gendt et al ., ; M. Li et al ., ; Zhang et al ., ]. The GPS‐PWV can be retrieved from GPS‐zenith tropospheric delay (ZTD) with the help of two key meteorological parameters, namely, the weighted mean temperature ( T m ) and the pressure ( P s ).…”

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