Assessment and Validation of Small-Scale Tropospheric Delay Estimations Based on NWP Data

Area of Science:

• Geodesy and Geophysics
• Atmospheric Science
• Meteorology

Background:

• Zenith wet delay gradients are crucial for precise positioning using Global Navigation Satellite System (GNSS) data.
• Numerical Weather Prediction (NWP) models offer potential for estimating these gradients over large areas.

Purpose of the Study:

• To investigate the applicability of NWP data for characterizing horizontal zenith wet delay gradients.
• To assess NWP data accuracy against GNSS-derived estimates.
• To analyze gradient behavior during extreme weather events.

Main Methods:

• Analysis of three years of NWP data over Scandinavia and Finland.
• Comparison of NWP-based gradient estimates with GNSS measurements processed by GipsyX/RTGx.
• Processing and analysis of NWP data during a storm event in August 2023.

Main Results:

• Maximum gradients of 40-50 mm/km were detected.
• Strong correlation observed between NWP-based and GNSS-based tropospheric delays.
• Weak correlation found between NWP-based and GNSS-based tropospheric gradients, attributed to NWP data uncertainty.

Conclusions:

• NWP data is applicable for characterizing horizontal zenith wet delay gradients, showing strong correlation with tropospheric delays.
• NWP data uncertainty limits precise gradient estimation, especially during extreme weather.
• Further research is needed to improve NWP resolution and accuracy for gradient analysis.