An introduction to China FY3 radio occultation mission and its measurement simulation

Bi, Yanmeng; Yang, Zhiyong; Zhang, Peng; Sun, Yueqiang; Bai, Weihua; Du, Qingyun; Yang, Guanglin; Chen, Jie; Liao, Mi

doi:10.1016/j.asr.2012.01.014

Cited by 41 publications

(20 citation statements)

References 16 publications

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“…This satellite is in a sun-synchronous orbit with orbit altitude and inclination of about 836 km and 98.75°. The primary mission of FY3C is scientific investigation of atmospheric physics, weather, climate, electron density, magnetosphere, and troposphere as well as stratosphere exchanges (Bi et al 2012). A GNSS Occultation Sounder (GNOS) has been placed on the satellite to ensure that the objectives can be achieved.…”

Section: Fy3c Satellitementioning

confidence: 99%

Enhanced orbit determination for BeiDou satellites with FengYun-3C onboard GNSS data

et al. 2017

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A key limitation for precise orbit determination of BeiDou satellites, particularly for satellites in geostationary orbit (GEO), is the relative weak geometry of ground stations. Fortunately, data from a low earth orbiting satellite with an onboard GNSS receiver can improve the geometry of GNSS orbit determination compared to using only ground data. The Chinese FengYun-3C (FY3C) satellite carries the GNSS Occultation Sounder equipment with both dual-frequency GPS (L1 and L2) and BeiDou (B1 and B2) tracking capacity. The satellite-induced variations in pseudoranges have been estimated from multipath observables using an elevation-dependent piece-wise linear model, in which the constant biases, i.e., ambiguities and hardware delays, have been removed. For IGSO and MEO satellites, these variations can be seen in onboard B1 and B2 code measurements with elevation above 40°. For GEO satellites, a different behavior has been observed for these signals. The GEO B2 pseudoranges variations are similar to those of IGSO satellites, but no elevation-dependent variations have been identified for GEO B1. A possible cause is contamination of the larger noise in GEO B1 signals. Two sets of precise orbits were determined for FY3C in March 2015 using onboard GPS-only data and onboard BeiDou-only data, respectively. The 3D RMS (Root Mean Square) of overlapping orbit differences (OODs) is 2.3 cm for GPS-only solution. The 3D RMS of orbit differences between BeiDou-only and GPS-only solutions is 15.8 cm. Also, precise orbits and clocks for BeiDou satellites were determined based on 97 global (termed GN) or 15 regional (termed RN) ground stations. Furthermore, also using FY3C onboard BeiDou data, two additional sets of BeiDou orbit and clock products are determined with the data from global (termed GW) or regional (termed RW) stations. In general, the OODs decrease for BeiDou satellites, particularly for GEO satellites, when the FY3C onboard BeiDou data are added. The 3D OODs reductions are 10.0 and 291.2 cm for GW and RW GEO solution with respect to GN and RN solution, respectively. Since the OODs in the along-track direction dominate the OODs reduction, no improvement has been observed by satellite laser ranging, which mainly validates the accuracy of the radial orbital component. With the GW BeiDou orbit and clock products, the FY3C orbits determined with onboard BeiDou-only data also show improvement in comparison with those determined with BeiDou GN products.

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Section: Fy3c Satellitementioning

confidence: 99%

Enhanced orbit determination for BeiDou satellites with FengYun-3C onboard GNSS data

et al. 2017

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“…Therefore, with growing demands for weather and climate information for disaster prevention and reduction, climate change response, ecosystems management, agriculture and forecasting, it is important that the Chinese Feng-Yun (FY) series satellites carry the GNSS occultation instrument to contribute to the global observing system. The GNOS mission (Bi et al, 2012) consists of a GNSS radio occultation explorer for remote sensing of both the Earth's neutral atmosphere and ionosphere, on China's FengYun-3 (FY3) 02 series satellites. The first of this series, FY3-C, was launched at 03:07 UTC on 23 September 2013.…”

Section: In 2002mentioning

confidence: 99%

An introduction to the FY3 GNOS instrument and mountain-top tests

Bai

Sun

et al. 2014

Atmos. Meas. Tech.

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Abstract. The FY3 (Feng-Yun-3) GNOS (GNSS Occultation Sounder) mission is a GNSS (Global Navigation Satellite System) radio occultation mission of China for remote sensing of Earth's neutral atmosphere and the ionosphere. GNOS will use both the global positioning system (GPS) and the Beidou navigation satellite systems on the China FengYun-3 (FY3) series satellites. The first FY3-C was launched at 03:07 UTC on 23 September 2013. GNOS was developed by the Center for Space Science and Applied Research, Chinese Academy of Sciences (CSSAR). It will provide vertical profiles of atmospheric temperature, pressure, and humidity, as well as ionospheric electron density profiles on a global basis. These data will be used for numerical weather prediction, climate research, and ionospheric research and space weather. This paper describes the FY3 GNOS mission and the GNOS instrument characteristics. It presents simulation results of the number and distribution of GNOS occultation events with the regional Beidou constellation and the full GPS constellation, under the limitation of the GNOS instrument occultation channel number. This paper presents the instrument performance as derived from analysis of measurement data in laboratory and mountain-based occultation validation experiments at Mt. Wuling in Hebei Province. The mountain-based GNSS occultation validation tests show that GNOS can acquire or track low-elevation radio signal for rising or setting occultation events. The refractivity profiles of GNOS obtained during the mountain-based experiment were compared with those from radiosondes. The results show that the refractivity profiles obtained by GNOS are consistent with those from the radiosonde. The rms of the differences between the GNOS and radiosonde refractivities is less than 3 %.

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“…His work showed that the root-mean-square difference is less than 0.2 % within an altitude range of 10-20 km. Using the pre-launch proxy data, Bi et al (2012) investigated the possible accuracy of the refractivity profiles from GNOS. The results from their simulations showed the refractivity profiles from the GNOS occultation to be highly accurate in the troposphere and lower stratosphere.…”

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confidence: 99%

Preliminary validation of the refractivity from the new radio occultation sounder GNOS/FY-3C

Liao

Zhang²,

Yang³

et al. 2016

Atmos. Meas. Tech.

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Abstract. As a new member of the space-based radio occultation sounders, the GNOS (Global Navigation Satellite System Occultation Sounder) mounted on Fengyun-3C (FY-3C) has been carrying out atmospheric sounding since 23 September 2013. GNOS takes approximately 800 daily measurements using GPS (Global Positioning System) and Chinese BDS (BeiDou navigation satellite) signals. In this work, the atmospheric refractivity profiles from GNOS were compared with the ones obtained from the co-located ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis. The mean bias of the refractivity obtained through GNOS GPS (BDS) was found to be approximately − 0.09 % (−0.04 %) from the near surface to up to 46 km. While the average standard deviation was approximately 1.81 % (1.26 %), it was as low as 0.75 % (0.53 %) in the range of 5-25 km, where best sounding results are usually achieved. Further, COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) and MetOp/ GRAS (GNSS Receiver for Atmospheric Sounding) radio occultation data were compared with the ECMWF reanalysis; the results thus obtained could be used as reference data for GNOS. Our results showed that GNOS/FY-3C meets the design requirements in terms of accuracy and precision of the sounder. It possesses a sounding capability similar to COSMIC and MetOp/GRAS in the vertical range of 0-30 km, though it needs further improvement above 30 km. Overall, it provides a new data source for the global numerical weather prediction (NWP) community.

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An introduction to China FY3 radio occultation mission and its measurement simulation

Cited by 41 publications

References 16 publications

Enhanced orbit determination for BeiDou satellites with FengYun-3C onboard GNSS data

Enhanced orbit determination for BeiDou satellites with FengYun-3C onboard GNSS data

An introduction to the FY3 GNOS instrument and mountain-top tests

Preliminary validation of the refractivity from the new radio occultation sounder GNOS/FY-3C

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