## 3 Evaluations of Data Quality

Table 3: Polarization of each channel of MWTS, MWHS, and ATMS in ARMS. about 0.3 K higher than that of FY-3F MWHS. The ATMS equivalent channels perform the best. Figure 4: Comparisons of mean O-B (**a**) and standard deviation (**b**) for FY-3F MWTS (black), FY-3E MWTS (grey), and NOAA-20 ATMS (red) equivalent channels. The horizontal coordinate is the MWTS channel number (units: K). Figure 3: Comparisons of mean O-B (**a**) and standard deviation (**b**) for FY-3F MWHS (black), FY-3E MWHS (grey), and NOAA-20 ATMS (red) equivalent channels. The horizontal coordinate is the FY-3E MWHS channel number (units: K). In terms of standard deviation (Figure 3b), FY-3F MWHS and FY-3E MWHS are comparable. On average, FY-3F MWHS is approximately 0.02 K higher than FY-3E MWHS for each channel. ATMS slightly outperforms MWHS. Overall, the differences among the three instruments are minor. MWHS performs poorly in channel 1 and channel 10. Figure 4a shows the mean bias comparison for MWTS equivalent channels, the mean biases of all channels for FY-3F MWTS and ATMS are within \(\pm\)2 K. The biases of FY-3E MWTS are relatively larger in channels 4, 16, and 17. FY-3F MWTS is, on average, approximately 0.3 K lower than FY-3E MWTS for each channel. Regarding standard deviation (Figure 4b), MWTS tends to perform less favorably than ATMS in the window channels (channels 1 and 2). With the exception of channels 1-3 and 11, FY-3E MWTS exhibits a higher standard deviation compared to both FY-3F MWTS and ATMS. FY-3F MWTS is, on average, approximately 0.13 K lower than FY-3E MWTS for each channel. Despite the differing standard deviations across the instrument channels, all instruments generally exhibit larger standard deviations in surface-sensitive channels and upper stratospheric channels. FY3F MWTS and ATMS slightly outperform FY-3E MWTS. Analyzing the differences between ascending and descending orbits is also an important aspect of evaluating new instruments. The differences may be caused by the smoothing scheme applied to the raw digital counts [27], which is related to the satellite's calibration issues. Figure 5 shows the results of ascending O-B minus descending O-B for MWHS, and Figure 6 shows that for MWTS. For MWHS (Figure 5a), excluding the window channels, the differences for most channels of FY-3F and FY-3E are not significant, falling within \(\pm\)0.2 K. FY-3F MWHS channel 1 is relatively more significant, with a bias of approximately 0.8 K, while for FY-3E MWHS, it is around 0.3 K. For the humidity detection channels 11-15 of FY-3F MWHS are more significant compared to those of FY-3E MWHS. In terms of standard deviation (Figure 5b), channel 10 of FY-3E MWHS exhibits a higher difference compared to that of FY-3F MWHS. For channels 11-15 of MWHS, the descending orbits of FY-3F MWHS are generally larger than that of the ascending orbits. Combining the above statistical results, the two instruments show their respective strengths and weaknesses in the performance of MWHS window channels, while the differences for other channels are generally not significant. Figure 5: Comparisons of O-B bias (**a**) and standard deviation (**b**) bias for the FY-3F MWHS (black) and FY-3E MWHS (grey) equivalent channel ascending (Asc) and descending (Desc) orbits (units: K). For MWTS (Figure 6a), there are discernible patterns in the differences between ascending and descending orbits for FY-3F and FY-3E. The average O-B for ascending orbits of FY-3F MWTS in channels 1-4 is greater than that for descending orbits, while the opposite is true for FY-3E. For FY-3E MWTS, the average O-B for ascending orbits in channels 5-17 is greater than that for descending orbits, while FY-3F exhibits the opposite trend. As shown in Figure 6b, the differences in the standard deviation of FY-3F and FY-3E are within \(\pm\)0.05 K, excluding the near-surface channels.