1. WGS-84 Seminar and Workshop
San Salvador
What’s New ?
Better ambiguity resolution
LC_AUTCLN now robust for all data with good pseudorange from ~1994
> 90% resolution after 2004, 80% ~2001, 70% ~1996
LC_HELP should be equivalent for small networks
IAU2000 replaces IAU1980 nutation model
Primary accuracy difference is in UT1 estimation (not relevant for regional studies)
Cannot use g-files created with a different model (use SP3 or change nutabl link)

2. WGS-84 Seminar and Workshop
San Salvador
What’s New ?
Better IGS orbits
Can run GAMIT (and GLOBK) with IGSF orbits fixed (BASELINE not RELAX)
IGSF (from SP3 files) now default, not SIOF (from g-files)
No discernible orbital error to 4000 km for data since at least 2004
Reprocessed orbits available later in 2009
Reprocessed global h-files available from MIT and SOPAC
Primary improvement is global ambiguity resolution
MIT files up to 300 global sites
SOPAC files up to 200 global sites plus regional networks
sh_get_hfiles allows selection of MIT reprocessed, SOPAC reprocessed, or SOPAC operational
* Note scale discontinuity at GPS Week 1400 (November 2008) with current IGS orbits and SOPAC operational h-files due to change to absolute PCVs

3. WGS-84 Seminar and Workshop
San Salvador
Quality of IGS Final Orbits
20 mm = 1 ppb
Source:

4. WGS-84 Seminar and Workshop
San Salvador
What’s New ?
Better models for atmospheric propagation effects
GPT replaces standard temperature and pressure for a priori ZHD
GMF replaces NMF for mapping functions
VMF1 ZHD and mapping functions from numerical weather models available as grid
Atmospheric loading ( ATML ) corrections available
Gridded values available from T van Dam at Luxemburg University and distributed on GAMiT/GLOBK ftp site (everest.mit.edu)
Should be used in conjunction with VMF1 ZHD
Sub-daily ( thermal tide ) components not yet handled correctly