## 3 Results
### Non-Conservative Force Modeling Effect of BDS  
After the identification of the SLR signature effect, SLR observations from seven high-performing stations were selected to analyze the modeling effect of non-conservative forces on SLR residuals. This section specifically focuses on the impact of non-conservative forces such as AT, ERP (albedo and infrared radiation), and SRP. ACs use different non-conservative force models to generate precise orbit products. Depending on the different models used by ACs, the modeling difference in the final per \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**High-Performing**} & \multicolumn{2}{c}{**All**} \\ \cline{3-6}
**AC** & **SAT** & **Mean** & **RMS** & **Mean** & **RMS** \\  & & **(mm)** & **(mm)** & **(mm)** & **(mm)** \\ \hline \multirow{3}{*}{CODE} & BDS-2 IGSO & \(-6.2\) & \(58.3\) & \(-0.2\) & \(59.3\) \\  & BDS-2 MEO & \(-23.0\) & \(39.8\) & \(-18.1\) & \(40.9\) \\ \hline \multirow{3}{*}{GFZ} & BDS-2 IGSO & \(2.7\) & \(55.5\) & \(4.3\) & \(57.2\) \\  & BDS-2 MEO & \(-24.9\) & \(52.6\) & \(-18.5\) & \(53.6\) \\  & BDS-3 CAST & \(30.3\) & \(50.3\) & \(28.7\) & \(50.5\) \\  & BDS-3 SECM & \(-48.5\) & \(61.5\) & \(-52.3\) & \(65.5\) \\ \hline \multirow{3}{*}{WU} & BDS-2 IGSO & \(-3.8\) & \(50.5\) & \(-5.4\) & \(50.9\) \\  & BDS-2 MEO & \(-13.7\) & \(49.5\) & \(-13.1\) & \(50.3\) \\ \cline{1-1}  & BDS-3 CAST & \(7.2\) & \(47.4\) & \(3.0\) & \(48.2\) \\ \cline{1-1}  & BDS-3 SECM & \(-12.7\) & \(51.5\) & \(-10.2\) & \(52.9\) \\ \hline \multirow{3}{*}{ESA} & BDS-2 IGSO & \(69.4\) & \(111.4\) & \(70.2\) & \(123.9\) \\ \cline{1-1}  & BDS-2 MEO & \(-2.2\) & \(46.5\) & \(5.1\) & \(50.0\) \\ \cline{1-1}  & BDS-3 CAST & \(46.8\) & \(51.2\) & \(45.4\) & \(51.3\) \\ \cline{1-1}  & BDS-3 SECM & \(-20.2\) & \(30.3\) & \(-22.3\) & \(33.9\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Mean offsets and RMS of the SLR residuals for precise orbit products of four ACs observed by high-performing SLR stations and all stations. Figure 6: The variation in SLR residuals with regard to nadir angle of four types of BDS satellites observed by different types of SLR stations. turbation acceleration may reach several nanometers per square second, which ultimately affects the accuracy of the orbits. SRP is the primary consideration factor for the non-conservative force models of navigation satellites, which cause an of about 80 to 130 nm/s\({}^{2}\). Four different SRP models, i.e., the empirical CODE orbit model (ECOM), the extended ECOM model (ECOM2), the a-priori box-wing (PBW) along with the ECOM model, and the PBW with estimated values along with the ECOM model, have been applied in GFZ, CODE, WU, and ESA, respectively. ECOM and ECOM2 are purely empirical models, which expressed the acceleration of SRP by estimating parameters in a DYB orthogonal frame [34]. PBW + ECOM adds an analytical model to the basis of ECOM, which is calculated by the solar radiation and characteristics of satellite surfaces. It is worth emphasizing that the perturbation generated by the thermal radiation pressure emitted from the materials of satellite surface is incorporated with SRP in a combined form [35]. The acceleration of ERP is a perturbation of 1 to 3 nm/s\({}^{2}\) caused by reflected solar radiation and emitted infrared radiation. For ERP, the widely used model for the GNSS satellite is the ERPBOXW model presented by [PERSON] [36], which considers both the modeling of reflected radiation and infrared radiation. ESA and WU deployed the ERPBOXW model for all BDS satellites and the BDS-2 MEO satellite, respectively, while CODE and GFZ do not consider the modeling of BDS ERP. AT is a perturbation caused by the signal transmission of satellites. The acceleration caused by AT can be modeled by the transmitting power of antenna and the mass of the satellite, which varies from 0.3 to 0.4 nm/s\({}^{2}\) for BDS-2 IGSO and BDS-2 MEO satellites.