## 5 Conclusions  
The Cherenkov Telescope Array Observatory (CTAO) requires accurate measurements of atmospheric conditions on its two sites and includes Raman LIDARs, among other common array elements [5,7,15] for continuous atmospheric characterization. The LIDARs need to operate at wavelengths covered by the observed spectrum of Cherenkov light in the range from 300 nm to 700 nm and need to be able to point at, or close to, the observed field of view of the CTAO telescopes in order to characterize its optical properties: mainly the vertical aerosol optical depths of the ground layer, clouds, possible stratospheric debris, and their wavelength dependence. We presented the prototype of a Raman LIDAR solution, the so-called pathfinder Barcelona Raman LIDAR (pBRL) in a second article within this special issue [16]. In this document, we have tested and analyzed the performance of the pBRL at two different \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**CTAO Requirement** & & **pBRL** & **BRL** * & **Comments** \\ \hline
**Cloud** & & & & & \\ Altitude Range & 2–20 km & ✓! & ✓ & pBRL reaches \(\sim\)35 km with the elastic lines at 355 nm and 532 nm, see Figure 28 (limited by street lighting and obtained before mirror re-aluminization). This corresponds to the requirement met for elevations higher than 35\({}^{\circ}\) for the pBRL. \\ VOD & 0.01–0.7 & ✓ & ✓ & The pBRL is able to detect and resolve clouds down to VODs of 0.01, see Figure 17 and VODs of at least 0.2 see Figure 26 with greatly reduced voltage settings. Higher VODs have not been observed, but should be easily detectable with canonical PMT gains of a factor of \(O(100)\) higher. \\ VOD RMSD & \(<\)0.03 & ✓! & ✓ & Iterative Klett analysis converges to correct LIDAR ratios (also in Ref. [9], where method was first implemented) above a sensitivity of \(VOD>0.01\). Formally, the analysis code still needs to be validated with dedicated simulations and real data sets on clouds through dedicated cross-calibrations (in preparation). \\ Base/Height RMSD & \(<\)300 m & ✓ & ✓ & Estimated \(O(100)\) m, depending on cloud height and optical thickness (see Figures 17 and 26). \\ \hline
**PBL** & & & & \\ Altitude Range & 0.5–9 km & × & ✓ & Current data sets do not cover full limiting altitude ranges, no showstoppers detected to be reached for BRL, with full operation of the near-range channels. \\ VAOD Range/RMSD & 0.03–0.7/\(<\)0.03 & ✓! & ✓ & Currently only achieved for the elastic lines over the full altitude range, and for elevations higher than 40\({}^{\circ}\). The Raman line analysis retrieves the correct LIDAR ratio, but is limited RMSD\(\gtrsim 0.05\) by residual ringing (see Figures 18 and 26). For these limiting cases, a continuous absolute calibration of the LIDAR (following Ref. [9]) is needed. To improve RMSD for the BRL, gated PMTs and fully operative near-range optics will be used [16]. \\ Height RMSD & \(<\)300 m & ✓ & ✓ & Less stringent than requirement on VOD RMSD, see Figures 18 and 26. \\ Ångström RMSD & \(<\)0.3 & ✓ & ✓ & pBRL: requirement met with spatial resolution better than 100 m, see Figure 25. Accuracies needs to be validated by dedicated cross-calibrations with other instruments (in preparation). \\ \hline
**Pointing** & & & & \\ Elevation & \(>\)25\({}^{\circ}\) & ✓! & ✓ & Accompanying technical paper Ref. [16]. \\ Azimuth & 0\({}^{\circ}\)–360\({}^{\circ}\) & ✓ & ✓ & Accompanying technical paper Ref. [16]. \\ \hline
**Obs. Time** & & & & \\ Extinction Profiles & \(<\)1 min & ✓ & ✓ & pBRL: Obtained in 50 s with 500 shots at 10 Hz repetition rate, see Figure 28. BRL: Further improvements expected due to higher laser PRF. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: CTAO requirements validation for the pBRL (this work) and the planned upgraded final version (BRL). Legend: * Expected. ✓: Validated. ✓! : Partially validated. ×: Not met.