Modeling global radiative responses and aerosol composition changes in EC-Earth3 from detailed new-particle formation predictions

<p>Representing detailed atmospheric aerosol processes in global climate models has proven challenging from both a computational and a parameterization perspective. A recent study on different Earth System Models (ESM) responses to small changes in the precursors to new aerosol particle formation (NPF) showed that two different models can produce opposite radiative outcomes in response to the removal of isoprene emissions (atmospheric cooling versus warming; Sporre et al., 2020).</p> <p>Here, we examine and test particle formation rate schemes and the sensitivity of the ESM EC-Earth3 applied in the work by Sporre et al. 2020. We have replaced the formation rate scheme based on Riccobono et al. (2014), derived exclusively from the relationship between organics vapors and sulfuric acid (H₂SO₄), with a more detailed molecular-model-based formation rate look-up table approach. This new scheme was created utilizing the Atmospheric Cluster Dynamics Code (ACDC) and currently applies tables of NPF from H₂SO₄ and ammonia. The tables include the effects of atmospheric H₂SO₄ and ammonia concentrations, temperature, ion-pair production, and cluster scavenging sink in the NPF process. We compare our model simulation results with ambient spring-time measurements of aerosol formation. We focus on boreal conditions and compare the performance of the new scheme to the previous model configuration to assess the simulations of local NPF events. For benchmarking, we also couple M7 with a one-dimensional high-resolution trajectory model ADCHEM with a more complex representation of aerosol chemistry. This enables us to compare observations of aerosol size distribution data from SMEAR II, a boreal measurement station in Finland (61.85&#176;N, 24.28&#176;E) with our ESM model results and with the detailed ADCHEM model results.</p> <p>Keywords: global modeling, new particle formation, aerosols, clouds, radiative effects, EC-Earth.</p> <p>&#160;</p> <p>Sporre, M. K., &#8230;, R., & Berntsen, T. K. (2020). <em>Large difference in aerosol radiative effects from BVOC-SOA treatment in three Earth system models</em>, Atmos. Chem. Phys., 20, 8953&#8211;8973. https://doi.org/10.5194/acp-20-8953-2020.</p> <p>Riccobono F., Schobesberger S., Scott C. E., et al. (2014) <em>Oxidation products of biogenic emissions contribute to nucleation of atmospheric particles</em>. Science. 344, 717&#8211;721, doi:10.1126/science.1243527.</p> <p>Session: AS3.2</p> <p><em>Consent: The presenting author is acting on behalf and with the consent of all authors of this contribution.</em></p>