## 5 Applications  
The LAnTeRN concept could potentially be deployed in a number of space- and ground-based applications to provide high-fidelity measurements of column GHG dry air mole fractions. The most notable space-based application is the continuous monitoring of GHGs at a network of sites spread over an extended region, e.g., Eastern/Western continental US or Western Europe, with a single transmitter in geosynchronous orbit, possibly as a hosted payload on a communications satellite. Figure 9: Differential transmission measurement _versus_ time at different lock-in integration time periods shows reduction in noise achieved through longer integration time. This is the same as that used in Figure 8, the measurement was done at 680 m with \(\sim\)3 pW of signal. \begin{table}
\begin{tabular}{c c c c c} \hline  & **Model** & **Measured** & **Model** & **Measured** \\ \hline Received Power (pW) & 106 & 90 & 18 & 18 \\ Ratio SNR (1 s lock-in) & 480 & 436 & 61 & 183 \\ Ratio SNR (60 s lock-in) & 3,701 & 1,366 & 471 & 1,057 \\ Differential Transmission & 0.965 & 0.966 & 0.920 & 0.921 \\ \hline Path & \multicolumn{3}{c}{680 m} & \multicolumn{3}{c}{1.6 km} \\ \hline \end{tabular}
\end{table} 
Table 3: Field test results compared to performance model predictions. A conceptual diagram of this configuration is illustrated in Figure 10. In this configuration small ground-based receivers, placed within line-of-sight of a single stationary steerable or wide-angle transmitter located in geosynchronous orbit, would be able to collect data day and night, as well as through thin clouds and heavy aerosol layers. The portability of the ground receivers can enable focused studies in areas of key scientific interest such as mega-cities, boreal forests, or the tropics. Unlike the pulsed low-earth-orbit method proposed by [PERSON] _et al._[32], this approach would allow a very robust validation campaign in order to determine and correct for bias, due to the continuous nature of the measurement. Initial calculations suggest that reasonable accuracies could be achieved with 8 W of average power from the transmitter and a 16 inch (406 mm) diameter telescope at the receiver and 2 minutes of integration at each receiver each hour. Due to this measurement concept being quasi-continuous, compared to a low-earth-orbit implementation, very high precision could be achieved through daily, weekly or monthly averages, and high accuracies could be obtained through extensive validation campaigns to determine bias. For a significantly lower cost than traditional space missions the LAnTeRN concept could be a key factor in monitoring, reporting, and verification for future policy, regulation, and treaties. The LAnTeRN concept not only provides the potential for a novel, robust, low-cost approach for providing space-based measurements of GHG column dry air mole fractions (DAMF) at a number of fixed sites given a single transmitter located in geosynchronous orbit, it also can be used to provide a non-invasive method for autonomous and continuous monitoring of CO\({}_{2}\) and other trace gas DAMF  
Figure 10: Conceptual depiction of the LAnTeRN space-to-ground implementation. Ground receivers could be grouped around specific sites of interest such as cities, factories, farmlands, forests, or other scientifically important regions, and then relocated to another site. Alternatively, the receivers could be spaced across a wide geographical area, providing near-continuous coverage valuable for continental, regional, and local scale modeling. and time-varying fluxes over an extended field site, such as a carbon sequestration facility, hydraulic gas fracking field, or volcano. The LAnTeRN approach could also provide a long-term technique for monitoring GHG distributions over an extended urban area.