## 3 Influence of Physical Properties of NS on Communication, Navigation, and TT&C Integration
### Atmospheric Loss in NS
#### 3.3.3 NS Atmospheric Flicker  
The irregular fluctuations of the atmospheric refractive index will cause fluctuations in the amplitude of the received signal; this phenomenon is called atmospheric scintillation. The duration of the fading caused by atmospheric scintillation is about several tens of seconds; from the perspective of communication, the channel corresponding to such a long duration experiences flat fading. Research shows that the standard deviation caused by the amplitude can be approximately expressed as a function of the antenna elevation angle, frequency, temperature, and water vapor pressure. For the situation where the elevation angle is greater than 4\({}^{\circ}\)[78],  
\[A(p)=\left[-0.061(\log_{10}p)^{3}+0.072(\log_{10}p)^{2}-1.71_{10}p+3.0\right]\Gamma \tag{10}\]  
Figure 6: Simulation results of the attenuation of clouds and fog in the NS under different conditions. (**a**) The loss of clouds and fog when the height of the cloud layer is fixed at 500 m. (**b**) The loss of clouds and fog under the condition of \(-8\)\({}^{\circ}\)C and moderate fog. (**c**) The loss of clouds and fog under the condition of 20 \({}^{\circ}\)C and moderate fog. (**d**) The loss of clouds and fog when the fixed launch angle is 60\({}^{\circ}\) and the loss rate coefficient ranges from 0.2 to 0.8.  
where, \(\Gamma=\frac{\Gamma_{ref}\frac{\gamma^{2}}{Z_{g}}(X)}{\sin{(\theta)}^{12^{-2}}}\); \(\Gamma_{ref}=3.6\times 10^{-3}+1.03\times 10^{-4}N_{net}\); \(N_{net}=\frac{3.73\times 10^{6}\log_{2}}{(273+t)^{2}}\), \(N_{net}\) is related to ambient temperature and humidity, \(e_{w}\) is water vapor pressure (mb), \(t\) is temperature; \(g(X)=\sqrt{3.86(X^{2}+1)^{\frac{1}{10}}\sin(\frac{11}{6}\arctan\frac{1}{X})}- 7.08X^{\frac{5}{6}}\), \(X=\frac{1.22\gamma D_{ref}}{L}\), \(\eta\) is the antenna efficiency, \(D_{g}\) is the antenna interface diameter, \(f\) is the frequency (GHz), \(L\) is the effective path length of atmospheric turbulence, \(L=\frac{2000}{\sqrt{\sin^{2}\theta+2.35\times 10^{-4}+\sin\theta}}\), the unit m.  
For the case where the elevation angle is less than \(4^{\circ}\)[78],  
\[A(p)=\left\{ \begin{array}{ll}10\log_{10}K_{w}-v+9\log_{10}f\\ \qquad-59.5\log_{10}(1+\theta)-10\log_{10}p(\text{average year})\\ 10\log_{10}K_{w}+9\log_{10}f-55\log_{10}(1+\theta)\\ \qquad-10\log_{10}p(\text{The worst month in an average year})\end{array} \right.\] (dB)  
where, \(K_{w}=p_{L}^{1.5}\times 10^{\frac{C_{0}+C_{Lat}}{10}}\), the variable \(p_{L}\) (%) represents the percentage of time in a certain month when the refractive slope at 100 m above the ground is lower than \(-100\) N units/km; \(C_{Lat}=\left\{ \begin{array}{ll}0&(|\phi|\leq 53^{\circ})\\ -53+\phi&(53^{\circ}<|\phi|\leq 60^{\circ})\end{array} \right.\), \(\phi\) represents the latitude of either the south latitude or the north latitude; \(C_{0}=\left\{ \begin{array}{ll}76&(h_{0}\leq 700\text{m})\\ 70&(h_{0}>700\text{m})\\ 76+6r&(\text{else})\end{array} \right.\), where \(h_{0}\) is the height of the Earth station antenna relative to the average sea level, and \(r\) refers to the part of the path that passes through the water or the adjacent coastal area. \(v=-1.8-5.6\log_{10}(1.1\pm|\cos 2\phi|^{0.7})\), when \(\left.\left.\left.\left.\left.\phi\right|\right.\right.\right.\right.\leq 45^{\circ}\), select the \"+\" sign, when \(\left.\left.\left.\left.\left.\left.\left.\phi\right|\right.\right.\right.>45^{ \circ}\right.\right.\), select the \"-\" sign.