Preliminary Assessment of BDS Radio Occultation Retrieval Quality and Coverage Using FY-3E GNOS II Measurements
Congliang Liu, Mi Liao, Yueqiang Sun, Xi Wang, Jiahui Liang, Xiuqing Hu, Peng Zhang, Guanglin Yang, Yan Liu, Jinsong Wang, Weihua Bai, Qifei Du, Xiangguang Meng, Peng Hu, Guangyuan Tan, Xianyi Wang, Junming Xia, Feixiong Huang, Cong Yin, Yuerong Cai, Wei Li, Peixian Li, Gottfried Kirchengast
Abstract
The FengYun-3E Global Navigation Satellite System (GNSS) occultation sounder II (FY-3E GNOS II) was launched on 5 July 2021. For the first time, based on the new GNOS II sensor, this mission realizes radio occultation (RO) and reflectometry observations using the navigation signals from the third-generation BeiDou System (BDS-3), and it is hence important to assess and analyze the BDS-3 remote sensing performances relative to other systems. Here, we assessed FY-3E GNOS II RO atmospheric retrievals by inter-comparing with corresponding data from the NCEP FNL global atmospheric analysis and FY-3D GNOS mission. The GNOS RO data quality and consistency of the different FY-3 meteorological satellites, i.e., FY-3D and FY-3E, as well as different GNSS systems (GPS, BDS-2, BDS-3) were analyzed. We find that the FY-3E GNOS II RO data exhibit better quality than FY-3D GNOS, particularly in the number, penetration height toward surface, and global coverage by BDS RO profiles, due to the integration of BDS-2 and BDS-3. Additionally, comparing with co-located NCEP FNL analysis profiles, the mean difference (and standard deviation) of the FY-3E GNOS II RO atmospheric refractivity profile retrievals is found to be smaller than 0.2% (and 1%), in the upper troposphere and lower stratosphere, from 5 to 30 km, and remains consistent at this accuracy and precision level with the FY-3D GNOS RO data. These features provide clear evidence for a high utility of the new GNOS II RO data for weather and climate research and applications.