|Title: Quantifying the single scattering albedo for the January 2017 Chile Wildfires from simulations of the OMI absorbing aerosol index|
Author(s): Jiyunting Sun, J. Pepijn Veefkind, Peter van Velthoven, and Pieternel F. Levelt
MS No.: amt-2018-40
This manuscript uses a case study to illustrate the derivation of the aerosol single scattering albedo (SSA) using observations from the OMI sensor of a large biomass-burning event in south Chile in 2017.
UV remote sensing of aerosols has not received the same level of attention as other sensors (such as MODIS/VIIRS) and studies like this one are a welcome addition to the general body of knowledge regarding the measurement of aerosol absorption from space. The paper is well laid out and its novelty resides in the combination of sensors utilized, its focus on single scattering albedo and aerosol height retrievals (as opposed to AOD and SSA) and its application using OMI observations. Overall, I think this paper can be published in its present form after some clarifications and corrections are included (mostly technicallso, I second the Editor’s comments that the Satheesh et al and the Gassó and Torres papers should be consider in this analysis plus the lack of mentioning of the recent SSA studies using OMI done by Jethva and Torres.
L325-326: the explanation provided does not make much sense to me. If there is little sensitivity to deltaZ , why the claim that there is an amplification of absorption in the layer?. My interpretation is that if there is an amplification of absorption, the AAI increases which means there is sensitivity to deltaZ. Please, revise the sentence.
Line 332-333: A similar conclusion was reached by Colarco et al (2017) when analyzing the sensitivity of OMI UVAI . Colarco, P. R., Gassó, S., Ahn, C., Buchard, V., da Silva, A. M., and Torres, O.: Simulation of the Ozone Monitoring Instrument aerosol index using the NASA Goddard Earth Observing System aerosol reanalysis products, Atmos. Meas. Tech., 10, 4121-4134, https://doi.org/10.5194/amt-10-4121-2017, 2017.
Lines 343-347: It should be mentioned that while the sensitivity is exists, in this case, it is very small; color range in the respective figure is from 0 to 1% which is negligible for practical purposes.
Section 3.1.1 Include the time difference between GOME-2 and OMI overpasses the respective type of orbits (ascending/descending)
Line 378: please remove this sentence unless you can make a more convincing case. The data set used in this study is not good enough for making assessments of the MODIS SSA assumption (which certainly needs to be addressed). You need at least well-collocated CALIPSO and Aeronet data. This does not mean that the comments regarding MODIS biases should be removed. The results are suggestive at most and it should be included.
Line 444: what is a “ ground pixel”? in this context it seems like the word pixel is enough.
Line 540: This method does not “retrieve an aerosol profile”, it retrieves an average aerosol height. Please correct this case and other that are included in the paper.
Figure 2: I see very little value in including a single-phase function in the figure. At reference to a paper should be enough and publication charges will be saved. Alternatively, you may want include additional phase functions to point out differences between aerosol models.
Figure 5: a) and b) seem to be inverted
Figure 6a: Put the same ticks in both x and y axis.
Figure 6: caption does not include reference or explanation of figure 6b.
Figure 7: since the colorbar is not the standard colorbar used in the official CALIPSO quicklooks, can you clarify if the dark red are cloud? The contrast between in smoke and cloud appears to be between orange and red but a clarification will be appreciated.
Figure 8 Caption: nowhere in the caption mentions the word AI. Is this the parameter displayed?