Abstract
Abstract. The rapid advancement of global navigation satellite system (GNSS) occultation technology in recent years has made it one of the most advanced space-based remote sensing technologies of the 21st century. GNSS radio occultation has many advantages, including all-weather operation, global coverage, high vertical resolution, high precision, long-term stability, and self-calibration. Data products from GNSS occultation sounding can greatly enhance ionospheric observations and contribute to space weather monitoring, forecasting, modeling, and research. In this study, GNSS occultation sounder (GNOS) results from a radio occultation sounding payload aboard the Fengyun 3 C (FY3-C) satellite were compared with ground-based ionosonde observations. Correlation coefficients for peak electron density (NmF2) derived from GNOS Global Position System (GPS) and Beidou navigation system (BDS) products with ionosonde data were higher than 0.9, and standard deviations were less than 20 %. Global ionospheric effects of the strong magnetic storm event in March 2015 were analyzed using GNOS results supported by ionosonde observations. The magnetic storm caused a significant disturbance in NmF2 level. Suppressed daytime and nighttime NmF2 levels indicated mainly negative storm conditions. In two longitude section zones of geomagnetic inclination between 40 and 80∘, the results of average NmF2 observed by GNOS and ground-based ionosondes showed the same basic trends during the geomagnetic storm and confirmed the negative effect of this storm event on the ionosphere. The analysis demonstrates the reliability of the GNSS radio occultation sounding instrument GNOS aboard the FY3-C satellite and confirms the utility of ionosphere products from GNOS for statistical and event-specific ionospheric physical analyses. Future FY3 series satellites and increasing numbers of Beidou navigation satellites will provide increasing GNOS occultation data on the ionosphere, which will contribute to ionosphere research and forecasting applications.
Highlights
The Global navigation satellite system (GNSS) occultation technique uses occultation receivers mounted on low earth orbit (LEO) satellites to collect GNSS signals that are refracted and delayed by the atmosphere and ionosphere
The comparison of ionosonde data and Fengyun 3 C (FY3-C) GNSS occultation sounder (GNOS) radio occultation products presented in this study shows that, in the majority of cases, GNOS NmF2 data are reliable and reasonable
Based on ionosphere data from the FY3-C GNOS payload combined with those from ground-based ionosonde, this study analyzed the characteristics of the global ionosphere response to the magnetic storm event in March 2015
Summary
The Global navigation satellite system (GNSS) occultation technique uses occultation receivers mounted on low earth orbit (LEO) satellites to collect GNSS signals that are refracted and delayed by the atmosphere and ionosphere. The excess phase due to the atmosphere and ionosphere is determined from measurements of the delayed carrier phase and the precise positions and velocities of the LEO and GNSS satellites. GNSS radio occultation technology makes global-scale measurements of the atmosphere and ionosphere possible. It has the advantages of high precision, high vertical reso-. Radio occultation technology has significant scientific value and a broad array of potential practical applications in climatology, meteorology, ionospheric studies, and geodesy
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