This manuscript integrates airborne, ground-based, and mobile measurements to map NH₃ emissions in two source regions in California. The paper is well written and the structure is clear. The results are important for improving the ammonia emission inventories. I only have minor comments as follows:

Presentation issues:

Section 3.1: Please quantitatively summarize the overall performance of airborne measurements to identify emissions sources, e.g., how many CAFOs/GPPs could be identified.

Figure 8: I am not sure if plume A to I were chosen based on the time series or emission sources - please clarify.  

Figure 9: There is no marked source in plume A. I suggest switching the colorbar to log scale and using the size of the marker to denote cattle population for each CAFO facility. Also, please add latitudes, longitudes, and wind direction for each panel.

Discussions: It would be helpful to compare the resolution of satellite maps versus airborne measurements in this study to highlight the advantage of this study.

Conclusions: I recommend stating the conclusions more quantitatively.

Minor comments:

Line 35: add citation

Line 38: Please cite commonly used ammonia emission inventories here besides Zeng et al., 2018

Line 57: needs citation for the first sentence of the paragraph

Line 160: Please briefly discuss the detection limit and validation results here instead of referring to the literature

This study presents measurements of atmospheric ammonia using ground-based and air-borne measurements at two different US cites. The study is more suitable for “Atmospheric Measurement Techniques” than ACP, but can be considered as a “Measurement Report” in ACP. The MS is relatively well-written and the measurements are valuable, but a substantial revision is necessary before it can be accepted for a publication.

Major points:

1. Introduction has to be enhanced with recent regional and global studies on atmospheric ammonia and policies related to it. The authors now list only two such studies, which are not enough for an Introduction to any study such studies. One example for a recent study is https://doi.org/10.1016/j.jclepro.2023.140424 and has to be cited.
2. Please compare your measurements with other available satellite or model results. Although the unit of NH₃ is different, you could still compare the general features.
3. What are the reasons for the diurnal variations of atmospheric ammonia (Figure 3)? However, this difference is not observed in Figure 2?
4. Why the meteorological data are taken from a model output? No AWS or measurements are available? How good are these model results? What is the horizontal resolution of the model? Did you interpolate the model results to the flight tracks?
5. What are the reason for the March and September NH3 differences (L380-390)?
6. Need a discussion of the limitation of the analysis and uncertainty of the retrievals.

Minor issues:

L60: and AIRS

L284-285: What is the scale that you are talking about? Mention this here