Global Influence of Organic Aerosol Volatility on Aerosol Microphysical Processes: Composition and Number

• Published in: Journal of advances in modeling earth systems 2024-10, Vol.16 (10), p.n/a
• Main Authors: Gao, Chloe Yuchao, Bauer, Susanne E., Tsigaridis, Kostas, Im, Ulas
• Format: Article
• Language: English
• Subjects: aerosol microphysics; aerosol mixing state; aerosol modeling; Aerosols; Carbon; Dust; Gases; Global aerosols; Measurement techniques; Microphysics; organic aerosol; Organic loading; Performance assessment; Photochemicals; Photochemistry; Tomography; Vertical profiles; VOCs; Volatile organic compounds
• ISSN: 1942-2466; 1942-2466
• DOI: 10.1029/2023MS004185

We present MATRIX‐VBS, a new aerosol scheme that simulates organic partitioning in an aerosol microphysics model, as part of the NASA GISS ModelE Earth System Model. MATRIX‐VBS builds on its predecessor aerosol microphysics model MATRIX (Bauer et al., 2008, https://doi.org/10.5194/acp‐8‐6003‐2008) and was developed in the box model framework (Gao et al., 2017, https://doi.org/10.5194/gmd‐10‐751‐2017). The scheme features the inclusion of organic partitioning between the gas and particle phases and the photochemical aging process using the volatility‐basis set (Donahue et al., 2006, https://doi.org/10.1021/es052297c). To assess the performance of the new model, we compared its mass concentration, number concentration, and activated number concentration to the original scheme MATRIX, and evaluated its mass concentrations in four seasons against data from the NASA Atmospheric Tomography Mission (ATom) aircraft campaign. Results from MATRIX‐VBS show that organics are transported further away from their source, and their mass concentration increases aloft and decreases at the surface compared to those in MATRIX. The mass concentration of organics at the surface agrees well with measurements, and there are discrepancies for vertical profiles aloft. In the new scheme, the global mass load of organic aerosols increased by 50%, there is also an increased number of particles at the surface and fewer activated ones in most regions. The new scheme presents advanced and more comprehensive capability in simulating aerosol processes. Plain Language Summary MATRIX‐VBS is a new aerosol microphysics component in NASA’s GISS ModelE Earth System Model. It is an advancement over the previous MATRIX aerosol microphysics model, incorporating how organics in the atmosphere are divided between gas and particle phases. We tested how well MATRIX‐VBS performs by comparing how much mass and how many particles it simulates compared to those from the original MATRIX model, and compared particle amounts from both models against real‐world data collected by NASA’s ATom aircraft campaign. We found that in MATRIX‐VBS, organic particles spread further from their source regions, increase higher up in the atmosphere, and decrease near the ground. The model’s simulations matched well with ground measurements, but there were some differences in higher altitudes. Overall, the new model showed a 50% increase in the global amount of organic aerosols, more particles at ground level, but fewer that c