Vienna Mapping Function - the effect on geodetic analyses

The Vienna Mapping Function (VMF) was developed by Johannes Boehm at TT-Viens. The coefficients of the extended fraction are derived by ray-tracing through actual meteorological data (he uses the ECMWF global data) rather than using best-fitting values to radiosonde data (as per the NMF) or just some atmospheric parameters (such as the IMF). Detailed information about the VMF can be found at Johannes' website here.

In January 2004 the GAMIT software was modified to incorporate both the IMF and the VMF mapping functions. This was made available to all users with the release of standard release version 10.2 (but most users don't know it yet!). It is invoked by changing NMFH/NMFW in sittbl. to VMFH/VMFW

12 months of GPS data have been processed for the period April 2004 to March 2005 (VMF coefficients for IGS sites are only available after 31 March 2004) using four, interwoven global subnetworks. The subnetworks chosen are those used by Tom Herring for the IGS Analysis performed at MIT. Daily site coordinates were extracted for all sites with more than 100 days of data included in the solutions. Click on the solution below to download files (in GAMIT ensum output format) for the following solutions:

Solution	Mapping Function	Elevation Cutoff Angle (deg)	Observation weighting scheme	Atmospheric Pressure Loading
vmf_5	VMF	7	elev-dep	none
vmf_5a	VMF	7	uniform	none
vmf_7a	VMF	7	uniform	applied
vmf_5b	VMF	7	elev-dep	applied
nmf_6	NMF	7	elev_dep	none
nmf_6a	NMF	7	uniform	none
nmf_8a	NMF	7	uniform	applied

Publications

The GMF: A new empirical mapping function based on numerical weather model data,
Boehm, J., A. E. Niell, P. Tregoning, H. Schuh
Geophys. Res. Lett., in press
pdf

Boehm, J., and H. Schuh (2004), Vienna Mapping Functions in VLBI analyses , Geophys. Res. Lett., 31, L01603, doi:10.1029/2003GL018984.
(An accepted version can also be found here.)

J. Boehm and H. Schuh, Vienna Mapping Functions, in: Proceedings of the 16th European VLBI Meeting, Leipzig, May 9-10, 2003, Verlag des Bundesamtes fuer Kartographie und Geodasie, 2003.