|I've reviewed the revised paper "Long-term historical trends in air pollutant emissions in Asia: Regional Emission inventory in ASia (REAS) version 3" by Kurokawa and Ohara. The authors have done an excellent job responding to the review comments and describing the assumptions and methods used in this work.|
Line 10: "The average total emissions in Asia during 1950-1955 and from 2010-2015 (growth rates in these 60 years)"
1950 - 2015 is 65 years?
(I see now on line 470 this is defined. Define this on first use of the 60-year period in the main text or, better yet, in the first paragraph of section "3.1 Trends of Asian and national emissions".)
"which were relatively large even in past years in Asia."
did the authors perhaps mean to say "even in recent Asia"?
(Otherwise I'm not quite sure what this means. In earlier times residential emissions dominate over other sectors in general before widespread industrialization)
It would be useful to get the author's perspective in section "3.4 Uncertainty" on uncertainty in emission trends given their extensive work with emissions data for this region. I realize this was not qualitatively estimated, but at least a qualitative discussion would be useful. In particular, as the author's noted in their response to reviewer comments, detailed information on emission control (and technology changes) were not available for all regions. So for some regions one would presume that recent trends might be more uncertain as a result due to lack of information. Similarly, for SO2, as mentioned in the current text, sulfur content in fuels is not known for the entire time period, which could impact trends.
Comments on Supplement: Kurokawa_and_Ohara_Supplement_Methodology
Page 36, Section on SO2 Emission Factors
It is not clear what the units are here. Are these the fraction of Sulfur in the fuel that is emitted as SO2? Please clarify.
Page 37 and forward, "Settings of emission controls".
In the China section, please clarify if "In 2015, reduction rates of SO2 emissions were assumed to be 75%, 63%, and 52% for (A), (B), and (C), respectively."
It is not clear if this is the assumed reduction per FGD unit, the total reduction as a result of the FGD deployment, or some other percentage (FGD penetration in 2015? Although this seems low.). Please clarify.
Throughout this section, where not otherwise noted (it is in some places), please indicate what the assumed reduction fraction for FGD units are (since penetration rates are already given in general).
Page 51 "Settings of emission controls" for primary particulate emissions.
Please clarify how these assumptions impact BC/OC. Were the PM2.5 reduction assumptions applied to BC and OC, or were some other assumptions used?
It appears that CO2 emissions are a mix of fossil CO2 emissions and short-cycle CO2 emissions (e.g. from biomass sources, etc.). If so please make sure in the data release that these are reported separately.
On page 142 it says: "(Note that uncertainties for SO2 here were only for ratios of sulfur in fuels emitted as SO2 and influences of uncertainties in sulfur contents in fuels were not included.)"
While on page 143 it says "For SO2, in addition to uncertainties for ratios of sulfur emitted as SO2, those in sulfur contents in fuels need to be taken into considered. "
This was a bit confusing. Please clarify.
Table 10.3. Settings of uncertainties of removal efficiencies
For removal efficiencies it would be useful to clarify how these uncertainties were applied. Given that this is used in an emission factor calculation as (1 - removal-efficiency), a multiplicative uncertainty could result in a removal efficiency larger than 1, but I assume something else was done (or max efficiency capped?).