This is a quite complete paper about the radiative forcing due to carbonaceous aerosols in China. The selected period extended from October 2016 to December 2017. Surface data were obtained from 36 monitoring sites. Although gridded data were also used. The analysis considers a radiative model. Organic carbon is divided in primary and secondary brown carbon, the radiative forcing of both tracers is investigated together with the influence of different atmospheric variables. Since the analysis is quite detailed and focused, only some few minor changes are suggested.

Most of the surface stations are placed at east of the country. The authors should comment the influence of such distribution on the results and if different results could be obtained with a homogeneous distribution of surface stations

Simulation was considered from October 2016 to December 2017. The authors should introduce a comment about the result representativeness since meteorological conditions may be quite different in different years. Perhaps the model is not so sensitive against meteorological conditions, or the weight of weather variables is weak.

The uncertainty of radiative forcing is quite important. Perhaps, authors could explain the reason for such uncertainty and if they consider procedures to make it smaller or cases where this uncertainty is small.

In this study, the authors investigate the radiative properties and direct radiative forcing of light absorbing carbonaceous aerosol over China using GEOS-Chem and the Rapid Radiative Transfer Model. A particular emphasis was placed on describing primary and secondary brown carbon; for this, the authors separated these species from organic carbon and modeled them as independent tracers. There are a lot of details involved in configuring the simulations. The choices that the authors made seem quite reasonable. The manuscript is well written, and the results are important. As such, in my opinion, this manuscript is appropriate for publication in Atmospheric Chemistry and Physics pending some clarifications and small corrections, as I list below.

1. lines 44-45: If Xu et al. (2024) estimated the DRF of Sec-BrC in China, the authors should make it clearer what all the differences are between Xu et al.’s (2024) approach and the present approach. Is the only difference the global emission inventory?
2. line 104: It appears that Eqs. (5) and (6) begin a sentence. I think that there need to be some introductory words before these equations in order to make it into a proper sentence.
3. lines 108-109: “indicating BC is wavelength independent within 880 nm” – Is BC assumed to be wavelength independent over a range of wavelengths? If so, this wording is not clear.
4. lines 141-142: “the entire China” – “the entirety of China”
5. lines 167-170: The authors should discuss the accuracy of using a standard Mie code for LAC, for which the particle shape is often not spherical. How do their single scattering results compare with results obtained in other studies accounting for the actual shape of such particles?
6. line 175: Are all of the values of DRF from every 3-hour time step used to calculate the annual mean DRF? If so, is the average a simple average or a weighted average?
7. line 188: “considering that the fraction” – “considering that a fraction”
8. line 207: “others k values” – “other k values”
9. line 208: A period is missing after “Saleh et al. (2014)”.
10. lines 488-197: The authors discuss some limitations of the study, such as their choice of external mixing state, fixed aging time, and empirical AAE. The authors should discuss whether changing any of the other details from section 2.3 regarding the configuration of the simulations to other reasonable options could change their results in any significant way.