A new generation of Chinese FY-3C microwave sounding measurements and the initial assessments of its observations

Abstract

ABSTRACTA new Chinese satellite, FY-3C, carrying second-generation microwave sounding instruments, was introduced and the observations were evaluated. On board FY-3C are the Microwave Temperature Sounder −2 (MWTS-2) and Microwave Humidity Sounder−2 (MWHS-2), and these devices are more advanced than those on board the previous satellites, FY-3A/B; the spectral and spatial resolutions of the devices are also higher than the Advanced Microwave Sounding Unit-A (AMSU-A) and the Microwave Humidity Sounder (MHS). The 50–60 GHz and 183 GHz sounding abilities are similar to Advanced Technology Microwave Sounder (ATMS) on board the Suomi National Polar-orbiting Partnership (SNPP). FY-3C and SNPP were launched in different orbits but are complementary in observation area. In addition, MWHS-2 is the first operational polar-orbiting, satellite-based sensor which has 118 GHz channels. Assessment of MWTS-2 and MWHS-2 observations indicate that striping noises are apparent from the observations. A technique combining principal component analysis (PCA) with Ensemble Empirical Mode Decomposition (EEMD) is used to extract the noise. The striping noise in the first PCA component is extracted from the data. It was determined that the bias and standard deviation (SD) of MWTS-2 noise was larger than that of the ATMS corresponding channels. The biases and SDs of the MWHS-2 noise were comparable in magnitude with ATMS moisture channels. After removing the noise, the biases and SDs of the difference between observation and simulation (O–B) for MWTS-2 were slightly larger than the ATMS. Biases of MWHS-2 were close to the ATMS. The O–B biases of MWHS-2 118 GHz channels were within the range from −0.6 to 0.2 K, and the SDs were approximately 0.5–1.2 K.