The study combines multiple-techniques to investigate atmospheric ammonia in Peninsular Southeast Asia with particular attention to biomass burning (BB) emissions. The analysis sounds scientific. This reviewer has a few comments for the authors to clarify some key points.

• The ratio of NH3 to particulate K in BB emissions should be cited and discussed.
• Satellite data of atmospheric NH3 represent the column density, which may or may not be correlated to the ground-level measurements. The authors have to clarify why “BB-induced NH3 emissions in the tropical monsoon environments can be much lower than previously anticipated,” in abstract.
• If BB emission is a minor source of atmospheric ammonia in Peninsular Southeast Asia. The instruction is misleading and needs to be reorganized.
• Section 3.2 is not readable. Please rewrite.
• Section 3.3, statistics test is missing and should be included.
• Effective numbers are not consist through the manuscript.

The analysis using the data from multiple-techniques does not link well.

NH3 is one of the key agents during the formation of secondary inorganic aerosols, which can make up over half of the ambient fine particles. Whilst an overwhelming contribution of agricultural activities to global and regional NH₃ budgets, biomass burning is believed to represent the most important source of NH3 to the atmosphere in fire-prone regions. In this study, multiple-techniques were used by Chang et al. to challenge this long-standing point of view. Their results were cross-validated and jointly suggested that during the dry wildfire season, biomass burning emissions represented a ubiquitous but comparatively small NH₃ source. Besides these specific results, this manuscript establishes a framework or methodology that could be extended to other fire-prone regions, based on the synergic use of concentration measurement, satellite retrieval, and isotopic analysis to constrain our understanding of NH3 sources in various atmospheres. The manuscript ends with an open question, but this may be the trigger to foster new research. Therefore I recommend publication after addressing the following issues.

Figure 1. The citation is incomplete.

Line 115-116. Specify the number of samples used to achieve the analytical precision you clamed.

Figure 3c. This figure is some sort of arbitrary. I suggest the author to replot it. The gridded population density can be extracted from WORDPOP. URL: https://www.worldpop.org/geodata/listing?id=77

Figure 7a. Numerous studies have confirmed that particulate potassium can hardly be the exclusive tracer of biomass burning, thus if possible, I suggest the authors to use levoglucosan to particulate potassium in Figure 7a.

Line 303-307 and Figure 7b. I appreciate the use of nitrogen isotopic source signatures of NH3 emitted from biomass burning based on the authors’ actual measurements. Since the insensitivity of the isotopic endmember of biomass burning-emitted NH3, it is not a big problem to include the result of Kawashima and Kurahashi (2011) to perform source apportionment study here. However, the isotopic endmember determined in Kawashima and Kurahashi (2011) is δ15N-NH4+ instead of  δ15N-NH3. I strongly suggest the authors to clarify this in their revised MS.