GNSS Atmospheric and Ionospheric Sounding – Methods and Results - Global Navigation Satellite Systems: Signal,Theory and Applications - page 361

90

60

30

0

-30

-60

-90

0 60 120 180 240 300 360

Longitude (deg)

Fig. 1. The distribution of global IGS GPS sites

2800

y(t)=1.071*10 4 -4.094*t+65.090*sin(2* π *t+1.013)+0.224*sin( π *t+0.385)

2750

2700

2650

2600

2550

2500

2450

2400

2350

2300

1998 1999 2000 2001 2002 2003 2004 2005 2006

Time (year)

Fig. 2. ZTD time series at TOW2 station, Australia. The solid line is the fitting results,
consisting of a linear decrease and seasonal components

2.2 Zenith tropospheric delay retrieval

The processing software must resolve or model the orbital parameters of the satellites, solve
for the transmitter and receiver positions, account for ionospheric delays, solve for phase