## 3 Results
### Consistency of Precise Products from Different Analysis Centers
#### 3.3.6 Effects of Sun Elevations on Consistency Results  
Following [PERSON] et al. [40], the quality of precise products could be affected by the sun elevations above the orbital planes. The orbit determination for low sun elevation angles is a challenge. Usually, the orbit quality is worse for low sun elevation angles due to the normal orbit mode. For further analysis, we re-compute the SISRE difference between GFZ and WHU precise products using the datasets over a month (DOY 122 to 152 in 2020) by dividing the satellites of each constellation into two groups, namely the satellites in eclipsing seasons and the satellites outside eclipsing seasons. When the sun elevations are lower than 8.6 for BDS GEO/IGSO and QZSS GEO/IGSO, 12.3 for Galileo, 13.1 for BDS MEO, 13.5 for GPS, and 14.3 for GLONASS, the satellites enter the phase of eclipse. The eclipsing satellites for each constellation during the analysis period are listed in Table A1 of Appendix A. The time spans in the parenthesis in Table A1 refer to the eclipsing periods. There are 10, 15, 13, 2, 2, and 12 eclipsing satellites for GPS, GLONASS, Galileo, QZSS IGSO, BDS-2 IGSO, BDS-2 MEO, and BDS-3 MEO during the analysis period, respectively, while there are no eclipsing satellites for QZSS GEO and BDS-2 GEO. The SISRE statistics are 3.4, 4.6, 2.0, 3.9, 2.5, 2.6, and 14.0 cm for GPS, GLONASS, Galileo, BDS-2 IGSO, BDS-2 MEO, BDS-3 MEO, and QZSS IGSO non-eclipsing satellites, respectively, while the SISRE differences are increased to 4.0, 5.4, 2.8, 5.6, 2.7, 2.5, and 15.0 cm for the corresponding eclipsing satellites, respectively. The consistency of precise products in eclipsing seasons is usually worse than that outside eclipsing seasons by several millimeters, but a significant consistency degradation of 44% can be found for BDS-2 IGSO satellites. It should be noted that the datasets on DOY 145 of 2020 (24 May 2020) for all the BDS-2 IGSO satellites as well as the datasets from 21:10:00 to 21:15:00 on DOY 135 of 2020 (14 May 2020) for all the BDS-3 MEO satellites are excluded from our analysis in this section, as the clock differences between GFZ and WHU during these periods of time show an anomalistic behavior, but it is not the case for those between GFZ and ESA. Thus, the derived SISRE statistics for the BDS-2 IGSO and BDS-3 MEO satellites in this section are better than those shown in Tables 5 and 6.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Items**} & \multirow{2}{*}{**ACs**} & \multicolumn{4}{c}{**ACs (for QZSS IGSO)**} & \multicolumn{4}{c}{**ACs (for QZSS GEO)**} \\ \cline{3-8}  & & **GFZ** & **WHU** & **CNES** & **GFZ** & **WHU** & **CNES** \\ \hline \multirow{3}{*}{Radial (cm)} & ESA & 15.4 & 18.6 & – & – & – & – \\  & GFZ & – & 16.8 & – & – & 5.6 & – \\  & WHU & – & – & – & – & – & – \\ \hline \multirow{3}{*}{Along-Track (cm)} & ESA & 6.0 & 13.5 & – & – & – & – \\  & GFZ & – & 12.8 & – & – & 328.0 & – \\  & WHU & – & – & – & – & – & – \\ \hline \multirow{3}{*}{Cross-Track (cm)} & ESA & 6.8 & 14.2 & – & – & – & – \\  & GFZ & – & 13.2 & – & – & 116.8 & – \\  & WHU & – & – & – & – & – & – \\ \hline \multirow{3}{*}{Clock (ns)} & ESA & 0.14 & 0.33 & – & – & – & – \\  & GFZ & – & 0.29 & – & – & 0.24 & – \\  & WHU & – & – & – & – & – & – \\ \hline \multirow{3}{*}{SISRE (cm)} & ESA & 14.8 & 15.5 & – & – & – & – \\  & GFZ & – & 14.4 & – & – & 32.4 & – \\ \cline{1-1}  & WHU & – & – & – & – & – & – \\ \hline \hline \end{tabular}
\end{table}
Table 7: RMSs of epoch-wise differences of precise satellite orbit and clock corrections among different ACs as well as SISRE statistics for QZSS IGSO and GEO satellites.