Table 1 Details of the experiment

Period

DOY 001–030, 2014, and DOY 001–030, 2020

System

Single GPS

Station

200 in red in Fig. 1

30 in blue in Fig. 1

Sampling

60 s

30 s

Weighting

0.2 m for pseudorange and 0.002 m for carrier phase

Low elevation observation and outliers are down-weighted

Ephemeris

Final orbit and clock product of Wuhan University

Phase Center Offset (PCO)/Phase Center Variation (PCV)

Corrected with igs14.atx

Ionosphere

DESIGN (Zhao et al. 2018)

Q4DIM correction

Troposphere

Global Pressure and Temperature 2 (GPT2) model with remaining estimated as a random walk process

Ambiguity

Float constant for each continuous arc