Minor correctionsshould be madeby the authors

General assesment

The article analyses different methodologies for the calibration of the water vapour channel of an atmospheric lidar. Furthermore, the results are disucssed for the same lidar instrument that has been used in different field campaigns and with different instrumental configurations since 2016. The authors evaluate the performance of different methodologies as well as assess the stability of the calibration over a long period (2016-2022).

The different calibration and validation methods are based on the comparison against collocated measurements made using independent instrumentation. First, radiosondes are used for the lida zr profile, which is the most common and standard method for calibrating the water vapour channel. In addition, measurements taken by a meteorological probe from an aircraft on spiral flights over the site are used in some field campaigns. Finally, the performnace of the calibration is analysed using  meteorological measurements on the surface and through reanalysis vertical profiles (ERA-5).

The results show that all the methodologies show a good agreement and great stability throughout the analysed period. The more significant and useful results indicate that it is possible to use ground-based measurements under atmospheric stability conditions to calibrate the lidar water vapor channel, obtaining differences similar to those obtained using radiosondes (mostly less than 1-2 g/kg).

The paper is well structured and well enough explained, although there are some grammatical details that could improve the reading and clarifying the understanding.

In my opinion the paper merit publication after some minor corrections since there are some aspects that could be easily addressed to improved the quality of the work and to increase its scientific scope. They are detailed next.

Specific comments:

P1-L27-29: What RMSE, bias and correlation coefficientes do the authors refer to? please specify.

P2-L1: What does "..there are no operational constraints" means? please specify.

P2-12: Please replace "Only recently has the need for better coverage of the lower troposphere emerged to improve constraints on the new generation of mesoscale models dedicated to weather forecasting " by "Only recently the need for better coverage of

the lower troposphere has emerged to improve constraints on the new generation of mesoscale models dedicated to weather forecasting"

P3-L15: Tha authors assert that: "Intrinsically, Raman lidar measurements have no bias". What does it means? can you provide a more detailed explanation?

P6- can you homogenize the format of the equations, in terms of the the way of writing the divisions?

P6-L10: should OR be writen with R as subindex as appear in equation 3?

P7-L12: please homognize the way to OR should be writen, in the text and equations.

P12-L12: How the authors reach that the uncertainties in WVMR is ~0.3 g Kg-1? I there any refference supporting it? The authors do not provide the way to derive WVMR from meteorological probes and therefore is not possible for the reader to address the propagation of uncertainties. Therefore, I think that this should be clarified, by refferences or more detailed explanation.

P12-L26: Is the same question that I explained just in the lines above, but in this case for radiosonde probes. It should be highlighted that the uncertainties of the reference measurements are really important because it will determines the uncertainty of the WVMR from lidar. 

P13-L19: What is the uncertainty associated to the WVMr derived from ERA5?

P21: Fig. 8 - 15. What is the vertical resolution used to perform the vertical comparisons between Lidar derived WVMR and in situ-aircraft, or ERA5 model?

P21-L11: How do you evaluate that the lower atmosphere had weak vertical gradient on the WVMR?

P36-L32. If the authors are talking about absolute uncertainty of k0, it should be follow by its units.