A new low-cost GNSS reflectometry system enables precise monitoring of sea level, ice thickness, and soil moisture using reflected satellite signals.
Sea level and sea ice thickness monitoring in Vihreäsaari harbor, Oulu Finland. The developed system observed the surface of the sea over various seasons for 16 months, enabling monitoring of sea ice thickness and sea level. Image Credit: University of Oulu.
Environmental remote sensing plays a vital role in tracking the effects of climate change. In his doctoral research, Master of Science Ankit Regmi introduces an innovative method that harnesses reflections of Global Navigation Satellite System (GNSS) signals from the Earth's surface. This approach allows for the study of surface materials and properties, including measurements of sea level, sea ice thickness, and soil moisture.
Regmi’s research was conducted in Vihreäsaari Harbor, Oulu, Finland, where his system monitored sea surface conditions across different seasons over a 16-month period. This long-term observation enabled the accurate tracking of sea ice thickness and sea level changes.
The study employs a cost-effective GNSS reflectometry system (GNSS-R), which utilizes a specialized antenna and commercially available GNSS receivers to capture both direct and reflected signals. By analyzing the signal-to-noise ratio, researchers can determine key surface characteristics.
The GNSS-R measurements presented in the study examine surface properties across different seasons and conditions. Sea ice thickness is estimated by observing the total height difference between GNSS interferometric reflectometry results and sea level data from the Finnish Meteorological Institute.
Changes in the GNSS signal passing through multi-layer ice are observed in the reflected GNSS parameter, enabling ice thickness measurement. Statistical parameters of the received GNSS data show a correlation with wind speed over open sea.
Ankit Regmi, Doctoral Candidate
Regmi’s research further explores how the relative permittivity of land and sea can be measured by analyzing changes in the polarization of reflected GNSS signals. To test the system’s capabilities in dynamic environments, he also conducted drone-based remote sensing experiments.
"Our GNSS-R system provides a cost-effective and versatile tool for environmental monitoring," says Regmi. "By delivering detailed insights into surface properties and changes, we can enhance our understanding of climate-related challenges and improve response strategies."
Potential Applications of GNSS-R Technology
Regmi highlights several key applications of this system, including:
- Climate Change Monitoring: Tracking sea level rise and ice melt with precise, real-time data.
- Agriculture: Measuring soil moisture to help farmers optimize irrigation and improve crop yields.
- Maritime Navigation: Enhancing safety and route planning by monitoring sea levels and ice conditions.
- Natural Disaster Management: Assisting in the prediction and monitoring of floods, storms, and other natural disasters, leading to better preparedness and response.