VMF3/GPT3: refined discrete and empirical troposphere mapping functions

Area of Science:

• Geodesy
• Atmospheric Science
• Radio Wave Propagation

Background:

• Tropospheric delay modeling is crucial for space geodetic techniques (GNSS, VLBI).
• Existing mapping functions, like VMF1, have limitations in accuracy, particularly at low elevation angles.
• Refining these functions is essential for high-precision geodetic measurements.

Purpose of the Study:

• To introduce Vienna Mapping Functions 3 (VMF3), an improved discrete mapping function.
• To address shortcomings in VMF1's empirical coefficients and elevation angle tuning.
• To present the Global Pressure and Temperature 3 (GPT3) model, a comprehensive troposphere model consistent with VMF3.

Main Methods:

• Development of VMF3 by refining VMF1 using ray-traced delays from the RADIATE tool.
• Calculation of new mapping function coefficients based on ray-tracing data.
• Generation of the GPT3 model using VMF3 data and meteorological quantities from GPT2wet.

Main Results:

• VMF3 demonstrates superior accuracy in approximating ray-traced delays compared to VMF1, especially at low elevation angles.
• VMF3 is recommended over VMF1 for applications requiring the highest precision.
• The GPT3 model provides a comprehensive, grid-based troposphere model consistent with VMF3.

Conclusions:

• VMF3 offers a significant advancement in modeling tropospheric delays for space geodesy.
• The new GPT3 model enhances capabilities for geodetic, meteorological, and climatological applications.
• The developed models provide a more accurate and consistent approach to troposphere modeling.