基于CRA40产品的对流层延迟计算及对比分析

As the release of China's first generation 40 a (1979-2018) global atmosphere and land reanalysis (CRA40) by China meteorological administration (CMA) in December 2020, the suitability, method and performance of CRA40 in tropospheric delay ray-tracing is initially investigated in this paper. Tropospheric delays in zenith and 5° elevation directions at 231 international GNSS service (IGS) and 213 crustal movement observation network of China (CMONOC) stations during the year of 2018 from CRA40 and two ECMWF reanalysis (ERA-Interim and ERA5) are ray-traced and evaluated by GNSS zenith total delay (ZTD) products and inter-comparison in globe and China area, respectively. The change law from the CRA40 zenith wet delay (ZWD) and slant wet delay (SWD) accuracy is also analyzed over China. The results show that the CRA40 ZTD difference RMS is about 1.40 cm, and it is slightly better than ERA-Interim in globe and similar to ERA-Interim in China area. By taking the ERA5 slant total delay (STD) as a reference, the CRA40 STD difference RMS is about 10.83 and 12.30 cm in globe and China area, respectively, which is not significantly different from ERA-Interim. The CRA40 ZWD and SWD accuracy over China is related to the climatic types, and the accuracy during winter is obviously better than that during summer in monsoon climate areas.