Characterizing GPS radio occultation loss of lock due to ionospheric weather

Abstract

Transient loss of lock is one of the key space weather effects on the Global Navigation Satellite System (GNSS). Based on the Constellation Observing System for Meteorology, Ionosphere, and Climate Global Positioning System (GPS) radio occultation (RO) observations during 2007–2011, we have analyzed the signal cycle slip (CS) occurrence comprehensively and its correlation to the ionospheric weather phenomena such as sporadic E (Es), equatorial F region irregularity (EFI), and the ionospheric equatorial ionization anomaly (EIA). The high vertical resolution of RO observations enables us to distinguish the CS resulting from different ionospheric layers clearly on a global scale. In the E layer, the CS is dominated by the Es occurrence, while in the F layer, the CS is mainly related to the EIA and EFI at low and equatorial latitudes. In the polar region, the CS is primarily related to polar cap electron density gradients. The overall average CS (>6 cycles) occurrence is ~23% per occultation, with the E (50–150 km) and F (150–600 km) layers contributing ~8.3% and ~14.7%, respectively. Awareness of the effect of the ionospheric weather on the CS of the low Earth orbit (LEO)-based GNSS signal could be beneficial to a variety of applications, including the LEO-based GNSS data processing and the corresponding hardware/firmware design.