This manuscript presents a comprehensive investigation on the emission factors, chemical, and optical properties of organics from Eurasian arctic-boreal and South African savanna biomass combustion in the lab. Brown carbon (BrC) is an important light-absorbing component in aerosol that affects the radiative balance in the atmosphere. The manuscript also investigated the effects of atmospheric dilution and aging on the optical properties of BrC. There are two comments that I wish the authors can address in the revision.

General comments:

1. It is stated in the abstract and conclusions that the comparison with African savanna biomass is an objective of this manuscript. However, throughout the manuscript, the comparison at least is not clearly stated. I would suggest giving a summary or some statements of comparisons on the main properties. Also, how do these data compare to North American forest fires? A brief discussion would put these data sets in a better context for modeling studies or for atmospheric implications.
2. What are the aerosol loadings in the aging experiments? At high loading, ozone could readily react with the gases and be lost onto particles, so the observed photochemical aging is mainly by ozone resulting in a low equivalent time (less than 2 days, Table 1)? Please comment on this issue.

Minor comments:

1. There are too many abbreviations which lead more confusions and less readability. It would be convenient to have a table or list. Some terms are only used for less than a few times, so it is not necessary to use abbreviations. For example, DMF, MeOH, PRD, etc. Define the variables or abbreviations when they are first used, then use the symbols or abbreviations, duplicated definition is not necessary, for example, L35,36,39, 117,140, 235.
2. L28, it would be better to use “determined” than “defined”.
3. Figure 3, what do the bottom right squares with lines indicate?
4. L669, how do you determine the OC1-4, Pyrol C and EC?
5. L509, how was the solubility determined?
6. L603-605, Figure 5, I don’t see a clear correlation between EC/OC and MAC if excluding the RWC data.
7. L684-685, how does the trend look like if excluding the chamber data? or how does it look like if it is plotted on a log scale?