In this study, the authors attempted to identify HLD sources across the Canadian Arctic Archipelago and adjacent areas by using FoO of DOD from 20-yr high-resolution MODIS retrievals as well as VIIRS aerosol type product, CALIOP products, and observations from two AERONET sites. The authors also compared the spatial distribution of FoO with G-SDS-SBM dataset and showed an overall agreement. There are also significant areas of disagreement between FoO from MODIS and VIIRS and between satellite retrievals and G-SDS-SBM dataset. Overall, I think this study provides insights for identifying HLD sources and can benefit future modeling and observational studies. I have a few comments for the authors to consider.

General Comments:

1. I wonder if MODIS products using the Dark Target algorithm (DT alone or combined DT/DB) can change the FoO of DOD and contribute to the uncertainties in identifying potential HLD sources, especially for coastal regions having both land and ocean.

1. I would suggest providing more details or high-level formulas to better explain how SI from G-SDS-SBM is calculated which may be helpful to explain the differences between the datasets and satellite retrievals. It seems to be mostly dependent on soil properties. It is not clear to me if SI depends on surface wind. SI being 1 indicates maximum capacity in cases of strong surface winds. However, the authors state that the derivation of SI does not need surface wind. What about the surface wind/friction velocity in the large green domain in Figure 6c compared to that in the red domain in Figure 6b and 6c. I also wonder how native (~0.008°) SI data were regridded to 0.1°.

Specific comments:

Line 9, please check if multiplication sign is used instead of letter x. Please check other places as well.

Lines 32-33, there are some more recent studies addressing this issue. I would suggest adding them. For example, Shi et al. (2022). Relative importance of high-latitude local and long-range-transported dust for Arctic ice-nucleating particles and impacts on Arctic mixed-phase clouds. Atmospheric Chemistry and Physics, 22, 2909-2935.

Line 235, why FoO DOD_B16 > 0.5 is much lower than FoO DOD_PG16 > 0.5 in the east of 95°W high-latitudes?

Line 238, for DOD_PG16, is it calculated when w < 1? Does that mean it is filtered as well?

Figure 3, I would suggest changing the color bar for the three bottom figures. It is just showing black over most places and gives less info.

Figure 5. I feel it gives limited information compared to lat-lon plot. How about showing similar lat-lon spatial distribution of FoO of CALIOP DOD using the algorithms from literature (e.g., Yu et al., 2015)?

Lines 362-363, this sentence is not clear to me. Could you explain a bit more and rephrase it?

Figure 6, I agree with the key point the authors tried to make. However, I would suggest at least trying to use different thresholds for FoO MODIS DOD and FoO VIIRS AT_DUST. There are significant differences between FoO MODIS DOD and FoO VIIRS.

Figure 7, I’m a bit confused about this figure. What’s the unit for FoO shown here. Is it the number of occurrence or the percentage as to total observations? It seems that blue and green lines correspond to the left y-axis while the brown line corresponds to the right y-axis. For right y-axis, is it for number of occurrence or the percentage?

Line 448, I would suggest showing the locations, as well as other selections of region such as the region in Figure 7, in Figure 8 or in the section 2.

For the conclusion part, I would suggest the authors give a high-level summary of some potential HLD sources in the order of confidence (i.e., agreements between MODIS, VIIRS, and G-SDS-SBM).

References

Yu, H., Chin, M., Bian, H., Yuan, T., Prospero, J. M., Omar, A. H., Remer, L. A., Winker, D. M., Yang, Y., Zhang, Y., and Zhang, Z.: Quantification of trans-Atlantic dust transport from seven-year (2007–2013) record of CALIPSO lidar measurements, Remote Sens. Environ., 159, 232–249, https://doi.org/10.1016/j.rse.2014.12.010, 2015.

The manuscript titled “Satellite-based evidence of dust emission over Northern Canada” by Ashpole and Wiacek attempted to use multiple satellite products including MODIS, VIIRS, and CALIOP to detect the frequency of occurrence of dust events for mapping possible dust sources. I think the methods to detect dust sources are generally adequate and useful for identifying dust sources. Different from another reviewer, I personally think using the Deep Blue over the land make sense since the authors are looking for dust sources from the land and not from the water bodies. I think this paper is helpful for constraining Canadian dust sources using a suite of satellite retrievals, and the study is helpful for the dust community. I have some general comments below, and I would suggest accepting this manuscript after a major revision.

Major comments:

Line 224: I would imagine that using 0.2 or an even smaller DOD threshold for FoO is needed for HLD sources like Canada. Using 0.5 as a threshold may miss out a lot of small local dust sources.

The difference between DOD_PG16 and DOD_B16 are not clear to the reader. The authors need to give more details on the differences between them and why the occurrence of DOD_B16> 0.5 are generally lower than that of DOD_PG16>0.5.

Line 317: I am not convinced that VIIRS mixed aerosols are mostly dust in Canada. They mentioned Kok (2011) but Kok showed that most emitted dust are coarse dust, not fine dust. They should stick with VIIRS dust (instead of VIIRS mixed aerosols) when interpreting possible dust sources.

Line 335: The authors used aggregated CALIOP aerosol vertical profiles with a coarse resolution of 5°x2°. A finer resolution might be needed for detecting smaller and local dust events.

Line 336: How did the authors exclude the diamond dust (ice crystal that are mistaken as dust) mistaken by CALIOP? There could be quite some precipitation in the summertime Arctic.

Figure 5: It looks like to me that CALIOP dust aloft be transported from elsewhere (e.g., the lower latitudes). How do you separate local sources from regional transport?

Line 351: The authors used two satellite instruments (MODIS and VIIRS) to generate two FoO maps. It is not clear to the reader which one is better for use. The authors should explain more on the pros and cons of each of them and how people can combine them to better constrain the Canadian dust sources.

Line 433: I would say that the climate change impacts on FoO is not clear from the time series in Fig. 7. I wonder what drives the interannual variability. Are there correlations between the wind / temperature / snow cover time series and the FoO time series?