Validation results of NmF2 and hmF2 derived from ionospheric density profiles of GNOS on FY-3C satellite

Ionospheric Peak Parameters Retrieved from FY-3C Radio Occultation: A Statistical Comparison with Measurements from COSMIC RO and Digisondes Over the Globe

“…In addition, due to the random fluctuations and steep gradients of the plasma density along the GPS ray path, the influences of observation errors and the approximations used in the inversion process, gross errors may exist in the inverted EDPs [37]. It was found that some questionable EDPs, e.g., some EDPs with exceedingly irregular fluctuations in the height variations of electron densities and some EDPs with positive topside gradients, exist in the downloaded COSMIC-RO and FY-3C RO products [19,38]. In this work, the qualities of FY-3C and COSMIC RO EDPs are checked using the criteria applied in the references [37][38][39], which are summarized in Table 1 [40].…”

“…The FY-3C satellite, which was launched in September of 2013 and finally operates in the orbit of 836 km altitude and 98.75 • inclination, is able to track the occultation signals of both GPS and BDS simultaneously [12,[17][18][19]. The FY-3C RO ionospheric products, including the time and location of the RO events and the corresponding electron density profiles (EDPs), have been provided by the National Satellite Meteorological Centre (NSMC) since 2014, whose quality has been validated in some comparisons with the observations from COSMIC RO mission and digisondes [12,19].…”

“…The FY-3C satellite, which was launched in September of 2013 and finally operates in the orbit of 836 km altitude and 98.75 • inclination, is able to track the occultation signals of both GPS and BDS simultaneously [12,[17][18][19]. The FY-3C RO ionospheric products, including the time and location of the RO events and the corresponding electron density profiles (EDPs), have been provided by the National Satellite Meteorological Centre (NSMC) since 2014, whose quality has been validated in some comparisons with the observations from COSMIC RO mission and digisondes [12,19]. COSMIC is the first LEO constellation designed for GNSS RO observations, which has provided more than two million EDPs since it was launched in 2006 [3,6], while digisonde is the traditional technique for measuring the ionosphere status below the peak heights with high accuracy and reliability [20][21][22].…”

“…In most previous studies on the validation and the application of the FY-3C RO ionospheric products, the time periods concerned about are generally not longer than one year. For example, Mao et al [12] validated the FY-3C RO EDPs for 92 days in 2013, from day of year (DOY) 274 to DOY 365, while Yang et al [19] studied the quality of FY-3C RO ionospheric characteristic parameters (ICPs) during the time period of only one year from October 1, 2013 to September 30, 2014. Yang et al [26] used the RO-derived EDPs provided by FY-3C from June 2014 to May 2015 to study the disturbance strength of sporadic E layers.…”

“…Furthermore, in previous studies about the validation of ionospheric products from CHAMP [27], COSMIC [28][29][30][31], FY-3C [12,19], and other RO missions [5] with digisonde measurements, when analyzing the variation of the quality of RO ionospheric parameters with different impact factors, the factors taken into consideration generally include latitude, season, and local time of the observation. For example, the comparison of FY-3C RO EDPs and digisonde-derived ones carried out by Yang et al [19] focused on the performance of FY-3C RO ICPs over different latitude regions and during daytime/night-time. Considering that the variations of these factors are not independent in the temporal and distribution of RO events, it is difficult to get a general conclusion on the impact of a certain factor on RO-derived ionospheric parameters.…”