In this article, Harb and Foroutan describe a measurement and complementary modeling study of lake spray emissions focused on the Great Lakes region.  The measurement section of the article describes the development of a lake spray source function using a marine aerosol reference tank, while the modeling section uses the Community Multiscale Air Quality model to simulate the lake spray impacts on aerosol number and mass concentrations during a period of strong winds.  Generally, I find the measurement section of the article a useful development in the field of lake spray emissions but find the modeling section incomplete.  Please see the specific comments below.

Major Comments:

1) CMAQ model: Despite being a widely-used model for research and policy, I don't believe that CMAQ is the appropriate tool to simulate the potential cloud impacts from lake spray aerosols.  The lack of aerosol-cloud interactions in the version of CMAQ used in this study means that the simulations are limited to the prediction of aerosol number concentrations without any information on the associated changes of cloud condensation nuclei or ice nuclei on cloud properties.  Quantifying the impacts on this aerosol source on cloud properties requires an online-coupled model.

2) CMAQ model configuration: I found little benefit from the SEA simulation to the study, and was surprised that it was included after the description of the lake spray source function having substantially lower emission fluxes than the sea spray source function.  If CMAQ continues to used in this study (see comment above), I'd strongly suggest that the SEA simulation be replaced with a simulation incorporating chemical speciation of the lake spray aerosol so that the impacts to regional atmospheric chemistry be quantified.

3) CMAQ model evaluation:  When discussing the model results, it's unclear whether including this emission source improves model performance.  I'd suggest that PM2.5 and PM10 observations from regulatory and IMPROVE sites in the region be compared to the model simulations.  If chemical speciation of the lake spray aerosol is included (see comment above), I'd also suggest that PM2.5 speciation from the IMPROVE and CSN sites in the region be used in the evaluation.

4) Typos:

Page 2, line 49: Should  be "These distinct..."

Page 16, line 371: Should be "as shown in Fig. 4b..."

Figure 8 caption: Should be "concentrations"

Figure 9 caption: Should be "concentrations"

Figure 10 caption: Should be "concentrations"

Page 22, line 470: Should be "Great Lakes..."

Page 22, lines 478-479: Should be "further north or south..."

FIgure 11 caption: Should be "from north to south..."

Page 25, line 514: Should be "impacts of these emissions..."

ACP Review “Experimental development of a lake spray source function and its

model implementation for Great Lakes surface emissions”

Summary: This manuscript describes the development of a new source function focused on aerosol emissions from freshwater lakes. The work builds from measurements of size and number concentration in an aerosol reference tank to develop a function that it applies in the CMAQ model to look at regional impacts. The function is primarily applied to the Great Lakes due to their size, particularly their fetch. Overall the work is detailed, considers the prior literature, and generally provides a useful function for use when considering freshwater emissions in models. There are some minor issues to fix related to aerosol nomenclature and some minor questions to be addressed, but overall is solid, detailed work and should be publishable after revision.

Specific Points:

• The authors in the abstract describe results with respect to fine aerosol (r < 0.2 um) and coarse aerosol (r ~ 1-2 um). Aerosol are usually defined in terms of diameter, not radius, so it would be helpful to readers to provide this in contact of diameter.
• In the abstract as written it could be interpreted that the authors looked just 1-2 and < 0.2 um, which would imply that 0.2-1 um was not a part of the calculations. That size range has considerable amounts of LSA, so it would be helpful to clarify this point.
• Coarse aerosol is typically defined, at least by EPA, as 2.5-10 um. Calling 1-2 um coarse, could be confusing as this would fall in the fine PM (PM₅) classification often used. IT would be helpful to explain and clarify this.
• Line 30: A common comment regarding aerosolization of bacteria/cyanobacteria is that it is components of the biological species that are typically aerosolized, not an intact bacterium. Please modify wording to reflect that the most prominent LSA sizes there would not be intact bacteria.
• The issue of low organic material in the simulated lake water and possibly from Claytor Lake is noted, it would be good to mention again in the conclusions as there is potential for fairly different emissions when more organics are present as is common across the Great Lakes, particularly in summertime.
• A key issue in the method section is that the authors refer to “mobility diameter” when they mean “electrical mobility diameter”. Mobility diameter in the aerosol world has a different definition not related to an aerosol’s movement in an electric field (see Ch. 3 and 5 of Hinds Aerosol Textbook). To avoid confusion for readers this should be referred to as d_em.
• Stitching together of SMPS and APS data would be preferable using the approach detailed in Khylstov 2004 AS&T, as opposed to removing that data. The sharp transion on Figure 2 at the SMPS/APS transition is notable and could be fixed by this approach.
• The wet versus dry size distributions are interesting. Could an inset or additional panel be included to make it easier to see the wet freshwater distribution in Figure 2a, it is almost impossible to see with how big the wet saltwater is.
• In a similar vein, for Figure 3 could the red size distributions (S and V) for 3c, 3d, 3e, and 3f be placed on the right axis or an inset provided? They are very difficult to distinguish from the baseline.
• Page 13, Line 315-316: please fix the sig figs for the numbers on these two lines. Error should not be listed with more than one digit (i.e. 21722 +/- 1964 should be 22000 +/- 2000).
• In the simulations for Figures 6-9, are larger particles even more enhanced (e.g. 3, 4, 5 um?) in the more traditional coarse definition?
• Figure 10, why in the lake case is there so much aerosol over the Atlantic Ocean? Particularly for the PM₅?