Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America

<p>Atmospheric organic aerosol (OA) mass concentrations can be affected by water uptake through its impact on the gas–particle partitioning of semi-volatile compounds. Current chemical transport models (CTMs) neglect this process. We have implemented the Binary Activity Thermodynamics model co...

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Main Authors: C. Serrano Damha, K. Gorkowski, A. Zuend
Format: Article
Language:English
Published: Copernicus Publications 2025-06-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/25/5773/2025/acp-25-5773-2025.pdf
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author C. Serrano Damha
K. Gorkowski
A. Zuend
author_facet C. Serrano Damha
K. Gorkowski
A. Zuend
author_sort C. Serrano Damha
collection DOAJ
description <p>Atmospheric organic aerosol (OA) mass concentrations can be affected by water uptake through its impact on the gas–particle partitioning of semi-volatile compounds. Current chemical transport models (CTMs) neglect this process. We have implemented the Binary Activity Thermodynamics model coupled to a volatility basis set partitioning scheme in the GEOS-Chem CTM, providing an efficient reduced-complexity OA model that predicts relative-humidity-dependent mixing and partitioning thermodynamics, while limiting the impact on computational efficiency. We provide a quantitative assessment of this water-sensitive OA treatment, focusing on a subdomain over North America. The updated OA scheme predicts a spatiotemporal mean enhancement in surface-level OA mass concentration of <span class="inline-formula">145 %</span> for January 2019 and <span class="inline-formula">76 %</span> for July 2019 compared to GEOS-Chem's most advanced OA scheme. The temporal mean surface-level OA organic mass concentration can increase by up to <span class="inline-formula">∼590 %</span> for January 2019 and <span class="inline-formula">∼280 %</span> for July 2019, with the greatest enhancements occurring over the ocean. The updated OA scheme also quantifies the OA-associated water content. The simulations show how different OA precursors and related OA surrogates contribute and respond to water uptake, including that due to changes in temperature and relative humidity over the diurnal cycle in selected winter and summer months. These results are independent of future CTM improvements involving updates to chemical reaction schemes and emission inventories. Our water-sensitive OA scheme allows for a better representation of the seasonal and regional variations in OA mass concentration in CTMs.</p>
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spelling doaj-art-d0f34557c8bb414c8a5e69bf31fded992025-08-20T03:46:21ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-06-01255773579210.5194/acp-25-5773-2025Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North AmericaC. Serrano Damha0K. Gorkowski1A. Zuend2Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, CanadaEarth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USADepartment of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, Canada<p>Atmospheric organic aerosol (OA) mass concentrations can be affected by water uptake through its impact on the gas–particle partitioning of semi-volatile compounds. Current chemical transport models (CTMs) neglect this process. We have implemented the Binary Activity Thermodynamics model coupled to a volatility basis set partitioning scheme in the GEOS-Chem CTM, providing an efficient reduced-complexity OA model that predicts relative-humidity-dependent mixing and partitioning thermodynamics, while limiting the impact on computational efficiency. We provide a quantitative assessment of this water-sensitive OA treatment, focusing on a subdomain over North America. The updated OA scheme predicts a spatiotemporal mean enhancement in surface-level OA mass concentration of <span class="inline-formula">145 %</span> for January 2019 and <span class="inline-formula">76 %</span> for July 2019 compared to GEOS-Chem's most advanced OA scheme. The temporal mean surface-level OA organic mass concentration can increase by up to <span class="inline-formula">∼590 %</span> for January 2019 and <span class="inline-formula">∼280 %</span> for July 2019, with the greatest enhancements occurring over the ocean. The updated OA scheme also quantifies the OA-associated water content. The simulations show how different OA precursors and related OA surrogates contribute and respond to water uptake, including that due to changes in temperature and relative humidity over the diurnal cycle in selected winter and summer months. These results are independent of future CTM improvements involving updates to chemical reaction schemes and emission inventories. Our water-sensitive OA scheme allows for a better representation of the seasonal and regional variations in OA mass concentration in CTMs.</p>https://acp.copernicus.org/articles/25/5773/2025/acp-25-5773-2025.pdf
spellingShingle C. Serrano Damha
K. Gorkowski
A. Zuend
Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America
Atmospheric Chemistry and Physics
title Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America
title_full Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America
title_fullStr Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America
title_full_unstemmed Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America
title_short Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America
title_sort implications of reduced complexity aerosol thermodynamics on organic aerosol mass concentration and composition over north america
url https://acp.copernicus.org/articles/25/5773/2025/acp-25-5773-2025.pdf
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AT kgorkowski implicationsofreducedcomplexityaerosolthermodynamicsonorganicaerosolmassconcentrationandcompositionovernorthamerica
AT azuend implicationsofreducedcomplexityaerosolthermodynamicsonorganicaerosolmassconcentrationandcompositionovernorthamerica