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NRT Notification Detail

An initial assessment of the quality of RO data from FY-3E

DATE: 2025-06-19 12:52
TYPE: NRT-GTS

Description

Dear ROM SAF GTS User

Issued: 2025-06-19 12:49 UTC

We are pleased to release a ROM SAF report which contains an initial assessment of the quality of GNSS Radio Occultation data from the Chinese FY-3E missions: https://rom-saf.eumetsat.int/general-documents/rsr/rsr_47.pdf

Abstract:

Feng-Yun 3E is a satellite flown by The Chinese Meteorological Agency (CMA) and the National Remote Sensing Centre of China (NRSCC). The satellite was launched on the 4th July 2021 in a sun synchronous orbit. On board the satellite has a GNSS Radio Occultation Sounder – 2 (GNOS2) instrument measuring the phase delay between a GNSS satellite and the low earth orbiting satellite. Observations from the GNOS2 instrument were first received over the Global Telecommunications system in March 2024.

The performance of the bending angles and the refractivity from FY-3E have been assessed and compared to similar observations such as those from FY-3D and Metop-C. Overall the quality of observations is similar to that seen from other operational instruments. The bending angle observations indicated an improved standard deviation above 35 km compared to FY-3D but there was a greater positive bias above 50 km for rising occultations. For refractivity bias increases above 30 km as is seen for FY-3D and Metop-C. This bias is smaller than that seen in FY-3D.

An experiment assimilating FY-3E into the Met Office’s Global model system was also conducted. The results of this experiment indicate that the inclusion of FY-3E Bending Angle observations had a neutral to slightly negative impact.

Timeliness of FY-3E observations being disseminated on the GTS during September were slower when compared with FY-3D and Metop-C. Around half of the received observations from FY-3E would miss the global model assimilation cut-off.

It should be noted that in January 2025 the data processing software at CMA was updated, which appears to have improved the data quality. This report covers the period before this update was made.

Kind regards
The ROM SAF Team

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