Tropospheric Scintillation Fading on L-Band Signals Using Mountaintop-Based Radio Occultation Measurements

Neeti Sonth, Jade Morton

Peer Reviewed

Abstract:	This study investigates tropospheric scintillation-induced signal fading in Global Positioning System (GPS) signals observed at L1, L2, and L5 frequencies. Data were collected from a multi-band software-defined radio (SDR) station at the summit of Haleakala, Hawaii, using a high-gain zenith-looking antenna connected to a Septentrio PolaRxS receiver. The study characterizes strong and weak troposphere scintillation events based on atmospheric profiles and meteorological conditions. Strong scintillation, linked to sharp refractivity gradients within the planetary boundary layer (PBL), shows a steep dependence on satellite elevation angle , with fading depths decreasing at higher elevations. Weak scintillation, mostly driven by humidity, cloud cover, or precipitation, exhibits a flatter elevation angle response at the L-band frequencies. These results align with theoretical modeling and previous studies. In addition, five years of data (2019–2023) are analyzed to examine broader fading trends. Seasonal and diurnal dependencies reveal that fading is slightly more prominent in summer than winter, and strongest during early morning hours. Fade durations at lower fading threshold are longer than those at a higher fading threshold with GPS L5 showing the longest durations, as expected. Overall, signal fading is strongest at low elevation angles, with higher values observed in Summer compared to Winter.
Published in:	Proceedings of the 2026 International Technical Meeting of The Institute of Navigation January 26 - 29, 2026 Hyatt Regency Orange County Anaheim, California
Pages:	165 - 176
Cite this article:	Sonth, Neeti, Morton, Jade, "Tropospheric Scintillation Fading on L-Band Signals Using Mountaintop-Based Radio Occultation Measurements," Proceedings of the 2026 International Technical Meeting of The Institute of Navigation, Anaheim, California, January 2026, pp. 165-176. https://doi.org/10.33012/2026.20535
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