# Investigation into the Effect of Atmospheric
## 3 Methodology of Investigation and Experimental Data Description
If there is no noticeable change in CNR (\(<\)the nominal CNR difference) when the PM\({}_{10}\), PM\({}_{2.5}\) and AQI ratios between sidereal days are large, then particulate matter and its concentration may have no or very insignificant impact on GNSS signal propagation. The maximum AQI index in the scale is 500 [24], the maximum AQI index in the data sets is 314 while the minimum AQI index is 20. The quality of the GPS data sets was checked using the Translate/Edit/Quality Check (TEQC) software [25], and no abnormal data is found in the data sets. Moreover, the temperatures, pressures and relative humidity values between the sidereal days in the data sets are similar, the effect of the small differences of them translated to tropospheric delay is analyzed in the next section. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Date** & **Time (hh:mm)** & **PM\({}_{10}\)** & **PM\({}_{2.5}\)** & **AQI** & **PM\({}_{10}\) Ratio** & **PM\({}_{2.5}\) Ratio** & **AQI Ratio** \\ \hline
6 November 2014 & 19:00 & 144 & 222 & 222 & 4.0 & 9.7 & 6.2 \\
6 November 2014 & 20:00 & 130 & 203 & 203 & 3.9 & 9.2 & 6.2 \\
6 November 2014 & 21:00 & 130 & 203 & 203 & 4.2 & 10.2 & 6.5 \\
6 November 2014 & 22:00 & 142 & 216 & 216 & 4.3 & 9.8 & 6.5 \\
6 November 2014 & 23:00 & 148 & 223 & 223 & 4.9 & 11.7 & 7.4 \\
7 November 2014 & 00:00 & 147 & 221 & 221 & 4.7 & 11.1 & 7.1 \\
7 November 2014 & 01:00 & 141 & 213 & 213 & 4.1 & 9.3 & 6.3 \\
7 November 2014 & 02:00 & 136 & 207 & 207 & 3.0 & 6.9 & 4.6 \\
7 November 2014 & 19:00 & 36 & 23 & 36 & - & - & - \\
7 November 2014 & 20:00 & 33 & 22 & 33 & - & - & - \\
7 November 2014 & 21:00 & 31 & 20 & 31 & - & - & - \\
7 November 2014 & 22:00 & 33 & 22 & 33 & - & - & - \\
7 November 2014 & 23:00 & 30 & 19 & 30 & - & - & - \\
8 November 2014 & 00:00 & 31 & 20 & 31 & - & - & - \\
8 November 2014 & 01:00 & 34 & 23 & 34 & - & - & - \\
8 November 2014 & 02:00 & 45 & 30 & 45 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: PM\({}_{10}\), PM\({}_{2.5}\) and AQI indices and their ratios between the two sidereal days of Data set 1. Figure 3: GNSS reference stations in UNNC. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Date** & **Time (hh:mm)** & **PM\({}_{10}\)** & **PM\({}_{2.5}\)** & **AQI** & **PM\({}_{10}\) Ratio** & **PM\({}_{2.5}\) Ratio** & **AQI Ratio** \\ \hline  
\hline \hline \end{tabular}
\end{table} 
Table 2: PM\({}_{10}\), PM\({}_{2.5}\) and AQI indices and their ratios between the two sidereal days of Data set 2. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Date** & **Time (hh:mm)** & **PM\({}_{\bf 10}\)** & **PM\({}_{\bf 2.5}\)** & **AQI** & **PM\({}_{\bf 10}\) Ratio** & **PM\({}_{\bf 2.5}\) Ratio** & **AQI Ratio** \\ \hline
27 December 2015 & 20:00 & 55 & 48 & 55 & 0.7 & 0.6 & 0.7 \\
27 December 2015 & 21:00 & 55 & 49 & 55 & 0.7 & 0.7 & 0.7 \\
27 December 2015 & 22:00 & 56 & 50 & 56 & 0.7 & 0.6 & 0.7 \\
27 December 2015 & 23:00 & 57 & 53 & 57 & 0.8 & 0.8 & 0.8 \\
28 December 2015 & 00:00 & 56 & 50 & 56 & 0.8 & 0.7 & 0.7 \\
28 December 2015 & 01:00 & 54 & 48 & 54 & 0.7 & 0.6 & 0.7 \\
28 December 2015 & 20:00 & 75 & 74 & 75 & & & \\
28 December 2015 & 21:00 & 75 & 75 & 75 & & & \\
28 December 2015 & 22:00 & 76 & 78 & 78 & & & \\
28 December 2015 & 23:00 & 68 & 67 & 68 & & & \\
29 December 2015 & 00:00 & 74 & 75 & 75 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: PM\({}_{10}\), PM\({}_{2.5}\) and AQI indices and their ratios between the two sidereal days of Data set 4.