14 Mar 2022
14 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Experimental development of a lake spray source function and its model implementation for Great Lakes surface emissions

Charbel Harb and Hosein Foroutan Charbel Harb and Hosein Foroutan
  • Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, USA

Abstract. Lake spray aerosols (LSAs) are generated from freshwater breaking waves in a similar mechanism to their saltwater counterparts, sea spray aerosols (SSAs). Unlike the well-established research field pertaining to SSAs, studying LSAs is an emerging research topic due to their potential impacts on regional cloud processes and their association with the aerosolization of freshwater pathogens. A better understanding of these climatic and public health impacts requires the inclusion of LSA emission in atmospheric models, yet a major hurdle to this inclusion is the lack of a lake spray source function (LSSF), namely, an LSA emission parameterization. Here, we develop an LSSF based on measurements of foam area and the corresponding LSA emission flux in a marine aerosol reference tank (MART). A sea spray source function (SSSF) is also developed for comparison. The developed LSSF and SSSF are then implemented in the Community Multiscale Air Quality (CMAQ) model to simulate particle emissions from the Great Lakes surface from 10 to 30 November 2016. Measurements in the MART revealed that the average SSA total number concentration was eight times higher than that of LSA. Consequently, the developed LSSF was around one and two orders of magnitude lower than the SSSF in the fine (r<0.2 μm) and coarse (r∼1–2 μm) aerosol size ranges, respectively. Model results revealed that LSA emission flux from the Great Lakes surface can reach ∼105 m−2 s−1 during an episodic event of high wind speeds. These emissions only increased the average total aerosol number concentrations in the region by up to 1.65 %, yet, their impact on coarse-mode aerosols was much more significant with up to a 19-fold increase in some areas. The increase in aerosol loading was mostly near the source region, yet LSA particles were transported up to 1000 km inland. Above the lakes, LSA particles reached the cloud layer, where the total and coarse-mode particle concentrations increased by up to 3 % and 98 %, respectively. Overall, this study helps quantify LSA emission and its impact on regional aerosol loading and the cloud layer.

Charbel Harb and Hosein Foroutan

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-158', Anonymous Referee #1, 12 May 2022 reply

Charbel Harb and Hosein Foroutan

Data sets

Experimental development and model implementation of a lake spray source function: dataset. Charbel Harb and Hosein Foroutan

Charbel Harb and Hosein Foroutan


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Short summary
A model representation of lake spray aerosol (LSA) ejection from freshwater breaking waves is crucial for understanding their climatic and public health impacts. We develop an LSA emission parameterization and implement it in an atmospheric model to investigate Great Lakes surface emissions. We find that the same breaking wave is likely to produce fewer aerosols in freshwater than in saltwater, and that Great Lakes emissions influence the regional aerosol burden and can reach the cloud layer.