GPS Solutions

, Volume 18, Issue 1, pp 123–131 | Cite as

The TropGrid2 standard tropospheric correction model

  • Torben SchülerEmail author
Original Article


TropGrid2 is a new version of a tropospheric model that is based on climatology and provides tropospheric propagation delay corrections for standard positioning users without temperature, pressure and humidity measurements. Zenith hydrostatic and wet delays are modeled as special harmonic functions taking seasonal and diurnal variations into consideration. The grid-point values are height-reduced and can be interpolated horizontally to the user position. The database used to derive this model consists of more than 9 years of 3D numerical weather fields of the NOAA NCEP GDAS weather model. We validated this standard model using 10 years of GPS-derived zenith path delays at 290 International GPS service reference stations. The gridded version is accurate at a level of 3.8 cm (root mean square in zenith direction) on global average; the average long-term bias is −0.3 cm. The standard deviations computed by the model turn out to be slightly too pessimistic for almost all stations under investigation, in contrast to the site-specific version, which is only marginally (1 mm) more accurate on global scale.


Tropospheric propagation delay Standard atmosphere Zenith total delay Tropospheric correction model 



Crustal Dynamics Data Information System


European Centre for Medium-Range Weather Forecasts


ECMWF re-analysis (fields 1978–1994)


European Space Agency


TROPO ESA-developed Galileo tropospheric correction model


Global data assimilation system


Global tropospheric correction model for navigation


International GPS Service


Integrated water vapor


Minimum Operational Performance Standards


National Center for Environmental Prediction


National Oceanic and Atmospheric Administration


Numerical weather model


Precipitable water


Receiver-Independent Exchange Format


Root mean square




Zenith hydrostatic delay


Zenith path delay (synonym of: Zenith total delay)


Zenith wet delay



The author would like to express his gratitude toward NOAA/NCEP for making the GDAS real-time weather fields from June 1999 to September 2008 available. The supply of reference zenith path delays processed from GPS data by the IGS is highly appreciated. Parts of this work were conducted in the COSMEMOS project that is partially funded by the European Union Framework Programme (FP7/2007-2013) under grant agreement no. 287162. All result tables used in this analysis are available from the author upon request.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.LRT9.2, Space GeodesyUniversity of the Federal Armed Forces MunichNeubibergGermany
  2. 2.Geodetic Observatory WettzellFederal Agency of Cartography and MappingBad KötztingGermany

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