Using Numerical Weather Prediction Model Derived Tropospheric Slant Delays in GPS Processing: a Case Study

• Main Authors: Maaria Nordman, Reima Eresmaa, Markku Poutanen, Heikki Järvinen, Hannu Koivula, Juha-pekka Luntama
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2007
• Subjects: Sodankylä
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.560.6485; http://www.geophysica.fi/pdf/geophysica_2007_43_1-2_049_nordman.pdf

The troposphere is one of the most significant sources of error in precise GPS (Global Positioning System) positioning solutions nowadays. Uncertainties in troposphere estimation distort the height component especially. We have implemented the troposphere slant delays derived from a numerical weather prediction model to GPS processing. In this case study we calculated 24 vectors for 61 days, the length of the vectors varying between 110 and 1100 km. When the slant delay is used instead of a standard troposphere model the variation in the positions solution’s up component is reduced considerably. At Sodankylä station (67.42ºN, 26.39ºE), for example, the standard deviation decreases from 5.9 cm to 1.3 cm for this 61-day period if no site-specific troposphere parameters are estimated. We also found that the length of the vector did not greatly affect the variance in the slant delay based positioning solutions. Key words: global positioning system (GPS), tropospheric delay, numerical weather model (NWM) 1.