|The authors did a lot of effort to improve their manuscript based on my suggestions.|
However, unfortunately, the authors did not take up the suggestion of reviewer #2.
I support his idea, that the analysis (one might call it evaluation) would win a lot from looking at other trace gases.
This is especially true, as one of the results -- at least from my point of view -- is, that we can not learn much from the comparison to ethane measurements, as the underlying ethane emissions are totally off.
The aim of this manuscript is to evaluate how the transport of a trace gas (finally targeted ethane) is effected by different physical parametrisations. Or, to phrase it differently, the main question is, which physical parametrisations do lead to the most realistic transport in the boundary layer and above. But this can not be answered by looking at ethane, if the emissions are thus far off, as in the present study. Here I also agree with the second reviewer, one could have learned more from a passive tracer study.
All the comparisons of a) different boundary layer schemes, b) the gain of re-initialisation, c) different initial and lateral boundary data and d) the horizontal resolution would be more meaningful, if gases which sources are better constrained than ethane would be compared.
I think, this point, raised by the second reviewer is the major week point of the study and is the reason, why I still considered the paper "major revisions".
Some detailed points of criticism:
1) from my point of view sect 2.3 should be Sect 2.2.1 and wiseversa, because the emission inventory belongs to the genereal setup of the WRF-Chem model, while a section "sensitivity tests" should provide information on the modifications of the general setup.
2) p.5, l. 15/16: "WRF-Chem provides a processed version ...." YOu honestly do not mean, that the model itself provides Emission data? Most probably the work is done by some institution ...?
3) Table 2: Provide a better description of the table. Necessary information: sensitivity tests divided by horizontal lines, The same simulation is mentions multiple times ....
Additionally, if I understand correctly Em7 is the same as Met5 / Init5 etc. Therefore it is rather confusing to add "+ Megan" here. This sounds as if Megan was only used in the to Em simulations.
4) Profile comparisons for ethane:
4a) provide somewhere the information of the definition of the "vertical bins" (0-1.5 km, 1.5-2 km ... ???)
4b) as the Ethane emissions are much too low, for the comparison of the shape of the profiles (which provide the information about the vertical transport), it would be better to compare "relative profiles", i.e. normed to their respective median, surface (or what else) concentration.
5) throughout the paper: "boundary conditions" is a very general term. This could be emissions, a land-cover data set or "lateral boundary conditions" therefore add the word "lateral" when talking about "lateral boundary conditions".
6) Fig. 3 lacks panels j,k,l and a colourbar.