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GPS Solutions

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

The TropGrid2 standard tropospheric correction model

  • Torben SchülerEmail author
Original Article

Abstract

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.

Keywords

Tropospheric propagation delay Standard atmosphere Zenith total delay Tropospheric correction model 

Abbreviations

CDDIS

Crustal Dynamics Data Information System

ECMWF

European Centre for Medium-Range Weather Forecasts

ERA15

ECMWF re-analysis (fields 1978–1994)

ESA

European Space Agency

GAL

TROPO ESA-developed Galileo tropospheric correction model

GDAS

Global data assimilation system

GTN

Global tropospheric correction model for navigation

IGS

International GPS Service

IWV

Integrated water vapor

MOPS

Minimum Operational Performance Standards

NCEP

National Center for Environmental Prediction

NOAA

National Oceanic and Atmospheric Administration

NWM

Numerical weather model

PW

Precipitable water

RINEX

Receiver-Independent Exchange Format

RMS

Root mean square

RTCA

RTCA, Inc

ZHD

Zenith hydrostatic delay

ZPD

Zenith path delay (synonym of: Zenith total delay)

ZWD

Zenith wet delay

Notes

Acknowledgments

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.

References

  1. Askne J, Nordius H (1987) Estimation of tropospheric delay for microwaves from surface weather data. Radio Sci 22(3):379–386CrossRefGoogle Scholar
  2. Collins JP, Langley RB (1999) Tropospheric delay: prediction for the WAAS user. GPS World 10(7):52–58Google Scholar
  3. Krueger E, Schüler T, Hein GW, Martellucci A, Blarzino G (2004) Galileo tropospheric correction approaches developed within GSTB-V1. In: Proceedings of ENC-GNSS 2004, Rotterdam, The Netherlands, 16–19 MayGoogle Scholar
  4. Krueger E, Schüler T, Arbesser-Rastburg B (2005) The standard tropospheric correction model for the European satellite navigation system Galileo. In: XXVIIIth general assembly of International Union of Radio Science (URSI), 23–29 October, New Delhi, IndiaGoogle Scholar
  5. Mendes VB, Prates G, Santos L, Langley RB (2000) An evaluation of the accuracy of models of the determination of the weighted mean temperature of the atmosphere. In: Proceedings of ION NTM 2000, US Institute of Navigation, Anaheim, CA, January, pp 433–438Google Scholar
  6. RTCA-MOPS (1999) Minimum operational standards for global positioning system/wide area augmentation system airborne equipment. 6,Oct 1999, RTCA/DO-229 B. RTCA Inc., Washington, USAGoogle Scholar
  7. Saastamoinen J (1972) Atmospheric correction for the troposphere and stratosphere in radio ranging of satellites. In: Henriksen (ed) The use of artificial satellites for geodesy. Geophys Monogr Ser 15:247–251. doi: 10.1029/GM015, AGU, Washington, D.C
  8. Schüler T. (2001) On ground-based tropospheric delay estimation. Doctoral Thesis, Studiengang Geodäsie und Geoinformation, Universität der Bundeswehr München, Nr. 73, NeubibergGoogle Scholar
  9. Schüler T, Hein GW, Eissfeller B (2000) On the use of numerical weather fields for troposphere delay estimation in wide area augmentation systems. In: Proceedings of GNSS 2000, Royal Institute of Navigation, Edinburgh, Scotland, MayGoogle Scholar
  10. Schüler T, Hein GW, Eissfeller B (2001) A new tropospheric correction model for GNSS navigation. In: Proceedings of GNSS 2001, 5th international symposium on global navigation satellite systems, Instituto de Navigacion de Espana, Sevilla, Spain, 8–11 MayGoogle Scholar

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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