Summary: DIAL Ozone profiles and IAGOS in situ data are presented during the 2022 ACROSS campaign on 21 days. These profiles are compared to the the satellite observations of Infrared Atmospheric Sounding Interferometer (IASI). Ancillary measurements from microlidar and radiosondes are also used for contextualizing the dynamics of the atmosphere. To better understand the regional transport of polluted air masses advected over the city,  daily ozone analysis of the Copernicus Atmospheric Service (CAMS) ensemble model 10 and on backward trajectories of the Paris city plume were also utilized.

Major Comments: This paper aims to discuss the importance of DIAL profiles on understanding the pollution transport on several high ozone days during ACROSS 2022. This effort is unfortunately not very well documented or referenced and reads closer to a campaign report, rather than a scientifically significant manuscript. There is mention of pollution and ozone precursors, but the authors have failed to pull in any sort of additional chemical observations besides ozone. CAMS or IAGOS NOx or other species will help bolster the conclusions of pollution transport or why there are potentially differences between the measurements. Furthermore, the IASI measurements are not carefully assessed, some work needs to be done in understanding the inherent value and uncertainty of these measurements. Comments below are intended to help the paper form a more thorough conclusion.

Minor Comments: There is a lack of appropriate and topical references throughout most of the manuscript. References to previous air quality/ozone campaigns should be refreshed for more recent work, in addition to expanding to other megacities.

L90 – Reference needed as to where this statement can be drawn from  “The accuracy of the lidar observations is altitude-dependent being of the order of 7µg.m−3 below 1000 m and occasionally increases up to 20 µg.m−3 above 2 km at midday”. Also recommend adding in a percentage difference. Please also note somewhere the conversion to ppbv for these observations - 1 ppb O3 = 1.96 µg/m³   at 25°C and 1 atm

Fig. 3 – Higher resolution terrain maps in the background would help better understand the ozone transport throughout the time. Adding in the wind barbs would also contextualize which direction the plume was moving.

Fig 6b – Is the CBLH actually over 3.5-3.8km? This seems unrealistic, even with >30C temperatures. Is this an aged polluted air mass that has recirculated associated with the synoptic high pressure system over the area as mentioned in the text. This figure should be clarified or manual inspection of the the CLBH algorithm should be addressed.  How did CAMS compare in terms of the RL and CLBH observations?

Fig 9 – It’s unclear where and when these IAGOS data overlap. For instance on 20220615, what is the coindidence in time for the CAMS (or IAGOS) and DIAL?

Table 2 – are the +/- associated with the variance of the dataset or uncertainty associated with the observations? The relative levels of uncertainty between high precision DIAL and in-situ observations needs to be described in comparison to the likely much higher uncertainty satellite observations.

L305 – This statement regarding excellent agreement cannot be fully stated until the uncertainty estimations are presented or some level of description of the apriori data for IASI is described. References are critically needed throughout this section.

Figure 13 – The IAGOS data does not replicate some of the higher ozone concentrations as observed in the DIAL measurements. What is the reason for this? This should also be labeled Partial Ozone columns in the x-axis.

Section 5.2  - This could be better visualized by bringing at least one of the FLEXPART simulation plots to the main paper rather than the supplemental.