Cloud response to co-condensation of water and organic vapors over the boreal forest
| Autor: | Liine Heikkinen, Daniel G. Partridge, Wei Huang, Sara Blichner, Rahul Ranjan, Emanuele Tovazzi, Tuukka Petäjä, Claudia Mohr, Ilona Riipinen |
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| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Zdroj: | XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) eISSN |
| Popis: | The condensation of organic vapors along with water vapor (co-condensation, CC) in adiabatic cloud parcel model (CPM) simulations enhances the number of aerosol particles that activate to form cloud droplets. The boreal forest is rich in organic vapors, but their role in CC has not been systematically investigated. In this work, we characterize conditions under which strong CC-driven cloud droplet number concentration enhancements (ΔCDNC) would be expected over the boreal biome. For this purpose, we performed a suite of CPM simulations,initialized with a set of concurrent state-of-the-art aerosol observations from the boreal forest of Finland (spring 2014). The degree to which CC impacts droplet formation is shown to be dependent on the initialization of the updraft velocity, aerosol size distribution, organic vapor concentration and volatility distribution. The predicted ΔCDNC is ~20%, which corresponds to activating particles 12–16 nm smaller in dry diameter, that would otherwise remain as interstitial aerosol. The highest ΔCDNC are predicted in the presence of a nascent ultrafine aerosol mode. Such aerosol size distributions are observed frequently in the studied boreal forest environment in spring and fall. UK Earth System Model simulations are further used to evaluate the frequencies to which such distributions are experienced by an Earth System Model over the whole boreal biome. They are lower than those observed at the measurement site and are modeled only during spring with large spatial variability. For accurate predictions of CC effects on cloud droplet number, the representation of the aerosol size distribution is of essence. The 28th IUGG General Assembly (IUGG2023) (Berlin 2023) |
| Databáze: | OpenAIRE |
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