Investigating the impact of HARMONIE-WINS50 (cy43) and LOTOS-EUROS (v2.2.002) coupling on NO₂ concentrations in The Netherlands by Yarce Botero et al.

This MS deals with the coupling of HARMONIE-WINS50 with LOTOS-EUROS models for air quality simulations. However, some details of the models and coupling process are missing or need to be clarified. The MS needs a major revision before it can be accepted. My comments are given below.

Major

1. What is the objective of this paper? Testing the meteorological forcing or the air quality simulation? This is not very clear and should be specified
2. Section 2.1, what drives the model, ECMWF, or NWP fields from the other model? In the Introduction, you stated the latter, but here you describe ECMWF!
3. Table 2: why there are two meteorological fields in LOTUS –EUROS?
4. Why there are large differences between measurements and model results (Figure 7)?
5. There are some language problems. Some are listed below, but not complete. Please correct them.

Minor

L25-28: The same lines are in the abstract. Rephrase them

L30: Which CTM?

L36. Delete “representation”

L38: delete “the simulated”

L43: by van Stratum et al. (2022)

L46: CTM, it's already abbreviated

L53: space after the bracket

L53: what do you mean by frequent coupling; there must be a time step for this

L56: by Ding (2013)

L61: “, respectively”

L100: similar to

L104: for this study comes from the

L109: observations or measurements

L111: What is SNELLIUS?

L124: emulate?

Figure 2: The sensor and model levels are different. But can’t you interpolate the model results to the sensor levels?

L211: ”, specifically”

L234-237: agree, but which model results are close to measurements or reasonable?

L244-245: “that must prevail in the impact of …” I do not understand this. Are you talking about the uncertainty of the model results? A bias in the model simulations?

Figure 6: Something is written on the maps, but is too small to read

L274-275: So what were the concluding results from the CHIMERE comparison?

L276: so the ECMWF wind data are not good?

L279, 297: in CTM like

L289-291: rephrase the sentence, hard to follow

Figure 10: “simulated tropospheric column of…”

L305-307: What is the error of tropospheric NO2 from TROPOMI?

L311: high values

General comments

The manuscript “Investigating the impact of HARMONIE-WINS50 (cy43) and LOTOS-EUROS (v2.2.002) coupling on NO₂ concentrations in The Netherlands” by Andres Yarce Botero et al. introduces the chemical transport model LOTOS-EUROS driven by reanalysis meteorological data from HARMONIE and ECMWF at different spatial resolutions. The authors evaluated the impacts of these two meteorological datasets on simulated NO₂ concentrations over the North Sea during April 2019. The authors also used some surface observations and satellite retrievals to validate the model performance.

In general, this manuscript fits the scope of the Geoscientific Model Development. However, it does have several drawbacks. The description of the observation datasets used in this study is too brief and lacks sufficient information. The authors should provide more details, such as specifying the TROPOMI dataset and including citations in Section 2. In the results section, the discussion and analysis are ambiguous. The authors included little statistics to validate the model performance and compare the simulated results between the two experiments. It’s not very convincing to only analyze the results at a few time snapshots (Figures 4, 6, and 8). The authors should include more details on the discrepancies between the observed and simulated NO₂ concentrations, as well as the factors that contribute to the differences between the two experiments. The uncertainties in air quality simulations driven by the two meteorological datasets have not been quantified. The conclusion of this paper is unclear. It’s not evident whether the use of more precise meteorological data could lead to a more accurate air quality simulation. Additionally, some figures should be re-organized to provide more effective information (Figures 2 and 6). The authors might uniform and enlarge the labels and legends in figures for better readability. Considering these issues, the reviewer recommends publication after major revisions. Please refer to the specific comments and technical corrections listed below.

Specific comments

P2, Line 43: Please add the citation for “HARMONIE cycle 43” or give more description on it.

P6, Table 1: “The variables are divided into static (purple), dynamic two (red), and three dimensions (green)”. Why do you include colors to represent the different variables?

“The variables underlined were calculated with other available variable”. I didn’t see any variables underlined. Please make sure the caption of Table 1.

P5, Line 139: Why did the authors use three nested domains in EC_LE experiment? Why didn’t the authors directly interpolate the original ECMWF meteorology to 0.025 deg and use one domain? I’m wondering how the LOTOS-EUROS runs three nested-domain simulation.

P8-9, Sections 2.3.1 and 2.4: The descriptions on surface NO₂ data and TROPOMI data are incomplete. Please give more information including the surface sites you selected, quality control on the raw data, the TROPOMI dataset you used in this study and the citations.

P7, Figure 2: I would suggest the authors to only show the comparison between the observations and ECMWF meteorology data at similar altitudes (e.g. 20 m, 40 m, and 200 m) in Figure 2a. It’s very hard to distinguish the observations and reanalysis data in current figure. Why didn’t the authors add the HARMONIE meteorology data in Figure 2a?

It would be better if the authors can add the altitudes of the sensors, the ECMWF and HARMONIE levels in Figure 2b.

P9-10, Section 3.1: I would suggest the authors to include some statistics such as NMB, RMSE, and correlation coefficients between the observations and ECMWF/HARMONIE meteorology data in the main text. The current analysis is too ambiguous.

P9, Figure 3: Is this the monthly mean daily temperature cycle in April 2019? The symbols and texts in Figure 3 are too small to identify.

P11, Line 204: The relative difference in Figure 5b is defined as “((EC_LE )-(HA_LE ))/(EC_LE)”. But in Line 204, it’s defined as “((EC_LE )-(HA_LE ))/(HA_LE )”. Please clarify it.

P11, Figure 5: Is this the monthly mean surface NO₂ concentrations in April 2019? Please clarify this in the caption.

P12, Line 215-226: Why did the authors only compare the simulations with the TROPOMI observations on April 22? I would suggest the authors to do a general comparison during April 2019 and provide more accurate statistics for model validations.

P13, Figure 6: I would suggest the authors to unify the units of tropospheric column of NO₂ simulated by two experiments and observed by TROPOMI. Please use the same color bars and add the same map in Figure 3c. I cannot identify which experiment performed better compared to the TROPOMI observations based on current figure.

P12, Line 235-237: “These differences may be attributed to using different meteorological and emission data in the two configurations…”. Why did the authors use different emission data in the two configurations? Based on Table 2, the emission data should be the same in the two experiments.

P12, Line 227-237: I would suggest the authors to provide more informative discussion on the differences of NO₂ concentrations and Kz coefficients. I’m wondering what meteorological factors cause the differences of the simulated NO₂ concentrations. Why did the authors only analyze the Kz coefficients? Based on Figure 7, it’s hard to say which experiment performed better in simulating NO₂ concentrations. Again, I’d like to suggest the authors to quantify the differences between the simulations and the observations.

Technical corrections

P2, Line 43: “… (van Stratum et al., 2022)” should be “… van Stratum et al. (2022)”.

P4, Line 111: Please spell out the acronyms “ECGATE” to “SNELLIUS” when they first appear.

P9, Line 169: Please spell out the acronyms “TROPOMI” and add citations.

P12, Line 232: What’s the Kz coefficient?

P14, Figure 8: Please add (a) and (b) in the upper and lower panels.

P15, Figure 9: Please add (d) in the panel. Please clarify the unit “[m[2] s−1]” of Kz.