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Research School of Earth Sciences
Earth Physics

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


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

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.

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