Fine-Resolution WRF Simulation of Stably Stratified Flows in Shallow Pre-Alpine Valleys: A Case Study of the KASCADE-2017 Campaign

Round 1

Reviewer 1 Report

The manuscript «Fine-Resolution WRF Simulation of Stably Stratified Flows in Shallow pre-Alpine Valleys: a Case Study of the KASCADE-2017 Campaign» is devoted to the simulation of the air flows over complex terrain by using weather model with a fine enough horizontal resolution. The study corresponds to the good scientific level. However, I may indicate the following remarks:

1. You need improve introduction: The studies of the vertical structure of the atmospheric boundary layer have been performing by means of a number of methods: sodars, lidars, remote sensing method using analysis of the optical radiation (Slodar, S-Dimm+) in order to reveal the (universal/regional ) features of the physical processes. You can cite [2,3]
2. Line 108. «in due time»?

• You should indicate the values of Ri. Now it is not clear, authors study the conditions with near neutral stratification, slightly stably stratified flows or strong stably stratified flows when Ri>0.25.

1. WRF simulation results are sensitive to the selected schemes of parametrisation. Please indicate and give more attention to the  explanation of usage of  
2. Figure A1. Authors obtain important result - an observed spectrum of turbulence in the surface layer of atmosphere. This spectrum corresponds to the 10 m height above surface. Please indicate, it is important because the spectrum changes with height (In the surface layer the turbulence is 3D and isotropic: u,v,w for r<L ). Also, I may notice that this spectrum corresponds to the stably stratified atmospheric surface layer. In the paper authors show a similar spectra ([1] G. Kovadloet al "The study of turbulence and optical instability in stably stratified Earth's atmosphere", Proc. SPIE 9680, 21st International Symposium Atmospheric and Ocean Optics: Atmospheric Physics, 968074 (19 November 2015); https://doi.org/10.1117/12.2205997) in the near ground layer of the atmosphere.  
3. Table 1. «Global data forcing ECMWF ERA 1h time step…» Do you mean Era-5?

• As you study individual case (20 – 21 Feb), you should say about cloudiness amount because cloudiness affect the radiation balance of the earth surface, horizontal distribution of the air temperature and, hence, air movements.
• Your study shoe that in the ABL one may observe the air jets with the maximum of the wind speed corresponding to the height~ 500 m above earth surface. You should discuss  this effect in comparison of the results of another authors, for example:

-[2]Banakh V. Lidar observations of atmospheric internal waves in the boundary layer of the atmosphere of the coat of lake Baikal/ Atmos. Meas. Tech., 9, 5239–5248, 2016 https://doi.org/10.5194/amt-9-5239-2016

- [3]Shikhovtsev, A.Y., Kiselev, A.V., Kovadlo, P.G. et al. Method for Estimating the Altitudes of Atmospheric Layers with Strong Turbulence. Atmos Ocean Opt 33, 295–301 (2020). https://doi.org/10.1134/S1024856020030100

 

Author Response

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Reviewer 2 Report

This paper has done a good validation study about the fidelity of the WRF model in prediction of the fine-scale atmospheric variables in the boundary layer over a complex terrain. The authors used an observational data set from a stably stratified case to evaluate the WRF model results. The conclusion about the WRF model’s fine-scale model prediction capability in this kind of terrain condition is useful to the model development research and for the prediction of pollutant transport and dispersion in complex terrain.

 

I have a one comment, did you try other PBL turbulence parameterizations in the WRF besides QNSE for a possible improvements? Based on your turbulence integral scale analysis, the integral scale at 2m AGL was 3 to 8m. The 111m grid scale is probably to coarse to capture the energy from  large turbulence eddies. The QNSE probably is probably not a superior in this kind of resolution.

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I recomend to add doi to the references as well as verify the spectra.