Tab.1

Errors of each mapping function components of Xi’an area at elevation of 5°"

Fig.1

Hydrostatic (a) and wet (b) mapping function of Xi’an area during 2016 at elevation of 5°"

Fig.2

Histogram of mapping function errors"

Tab.2

Geodetic coordinates of each area"

Fig.3

Variation of average and standard deviation of hydrostatic and wet mapping function errors with elevation in different areas in 2016"

Fig.4

Variation of average and standard deviation of hydrostatic and wet mapping function errors with elevation in Xi’an during 20132016"

Tab.3

Fitting coefficients of mapping function errors and statistics of residual standard deviations"

Tab.4

Statistics of fitting accuracy when the coefficients of 2016 are changed with 3-year average ones from 2013 to 2015"

Tab.5

Coefficients of statistical parameters"

Tab.6

Slant path delay residuals of Xi’an cm"

Tab.7

Estimated wet delay errors of Xi’an cm"

Fig.5

Distribution of simulated observing orientations over the station (The outer circle represents the azimuthal axis, while inside diameter represents the elevation angle axis)"

Fig.6

Percentages of simulated observing orientations over various elevation angle (a) and azimuth ranges (b)"

Fig.7

Slant path delay errors of two different methods Red dash line for conventional method, blue solid line for two-step one"

Fig.8

Reference wet delay values and estimated ones by two methods Red line for reference values, blue line for conventional estimates, fluorescent blue line for two-step ones"

Tab.8

Slant path delay residuals of different areas cm"

Tab.9

Estimated wet delay errors of different areas cm"