(Near) Real-Time Snow Water Equivalent Observation Using GNSS Refractometry and RTKLIB

Area of Science:

• Geodesy
• Hydrology
• Remote Sensing

Background:

• Accurate snow water equivalent (SWE) data are crucial for hydrological monitoring and validating remote sensing products.
• Traditional methods are often manual and labor-intensive, limiting continuous in situ observations.
• Global Navigation Satellite System (GNSS) refractometry presents a promising automated approach for SWE estimation.

Purpose of the Study:

• To investigate the feasibility of using the open-source RTKLIB software for in situ SWE determination via GNSS refractometry.
• To assess the performance of RTKLIB in both post-processing and near real-time SWE estimation.
• To evaluate low-cost, fixed, and mobile GNSS refractometry setups for continuous and accessible SWE monitoring.

Main Methods:

• Reprocessing of existing GNSS data from a high-end setup (2016/17 season) using RTKLIB for post-processing validation.
• Deployment of a low-cost, fixed GNSS setup for continuous near real-time SWE estimation (2021/22 season).
• Design and evaluation of a mobile, low-cost GNSS setup for near real-time SWE measurements (March 2020).

Main Results:

• RTKLIB demonstrated applicability for post-processed SWE estimation using GNSS refractometry.
• Continuous near real-time SWE estimates were achieved with a low-cost, fixed GNSS setup.
• Both fixed and mobile setups confirmed the feasibility of near real-time SWE estimation.
• Mean relative bias below 5% was achieved compared to manual SWE observations for RTKLIB-processed data.

Conclusions:

• Open-source RTKLIB software enables accurate and cost-effective in situ SWE estimation using GNSS refractometry.
• The developed low-cost fixed and mobile setups facilitate continuous, near real-time SWE monitoring.
• GNSS refractometry with RTKLIB offers a viable alternative for enhancing snow hydrological studies and remote sensing validation.