Global simulations of aerosol processing in clouds
An explicit and detailed representation of in-droplet and in-crystal aerosol particles in stratiform clouds has been introduced in the global aerosol-climate model ECHAM5-HAM. The new scheme allows an evaluation of the cloud cycling of aerosols and an estimation of the relative contributions of nucl...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2008-12-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/8/6939/2008/acp-8-6939-2008.pdf |
| _version_ | 1818390986602053632 |
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| author | C. Hoose U. Lohmann R. Bennartz B. Croft G. Lesins |
| author_facet | C. Hoose U. Lohmann R. Bennartz B. Croft G. Lesins |
| author_sort | C. Hoose |
| collection | DOAJ |
| description | An explicit and detailed representation of in-droplet and in-crystal aerosol particles in stratiform clouds has been introduced in the global aerosol-climate model ECHAM5-HAM. The new scheme allows an evaluation of the cloud cycling of aerosols and an estimation of the relative contributions of nucleation and collision scavenging, as opposed to evaporation of hydrometeors in the global aerosol processing by clouds. On average an aerosol particle is cycled through stratiform clouds 0.5 times. The new scheme leads to important changes in the simulated fraction of aerosol scavenged in clouds, and consequently in the aerosol wet deposition. In general, less aerosol is scavenged into clouds with the new prognostic treatment than what is prescribed in standard ECHAM5-HAM. Aerosol concentrations, size distributions, scavenged fractions and cloud droplet concentrations are evaluated and compared to different observations. While the scavenged fraction and the aerosol number concentrations in the marine boundary layer are well represented in the new model, aerosol optical thickness, cloud droplet number concentrations in the marine boundary layer and the aerosol volume in the accumulation and coarse modes over the oceans are overestimated. Sensitivity studies suggest that a better representation of below-cloud scavenging, higher in-cloud collision coefficients, or a reduced water uptake by seasalt aerosols could reduce these biases. |
| first_indexed | 2024-12-14T05:06:21Z |
| format | Article |
| id | doaj.art-4a72c0fd5da24364b40749e202bcc7cd |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-14T05:06:21Z |
| publishDate | 2008-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-4a72c0fd5da24364b40749e202bcc7cd2022-12-21T23:16:05ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242008-12-0182369396963Global simulations of aerosol processing in cloudsC. HooseU. LohmannR. BennartzB. CroftG. LesinsAn explicit and detailed representation of in-droplet and in-crystal aerosol particles in stratiform clouds has been introduced in the global aerosol-climate model ECHAM5-HAM. The new scheme allows an evaluation of the cloud cycling of aerosols and an estimation of the relative contributions of nucleation and collision scavenging, as opposed to evaporation of hydrometeors in the global aerosol processing by clouds. On average an aerosol particle is cycled through stratiform clouds 0.5 times. The new scheme leads to important changes in the simulated fraction of aerosol scavenged in clouds, and consequently in the aerosol wet deposition. In general, less aerosol is scavenged into clouds with the new prognostic treatment than what is prescribed in standard ECHAM5-HAM. Aerosol concentrations, size distributions, scavenged fractions and cloud droplet concentrations are evaluated and compared to different observations. While the scavenged fraction and the aerosol number concentrations in the marine boundary layer are well represented in the new model, aerosol optical thickness, cloud droplet number concentrations in the marine boundary layer and the aerosol volume in the accumulation and coarse modes over the oceans are overestimated. Sensitivity studies suggest that a better representation of below-cloud scavenging, higher in-cloud collision coefficients, or a reduced water uptake by seasalt aerosols could reduce these biases.http://www.atmos-chem-phys.net/8/6939/2008/acp-8-6939-2008.pdf |
| spellingShingle | C. Hoose U. Lohmann R. Bennartz B. Croft G. Lesins Global simulations of aerosol processing in clouds Atmospheric Chemistry and Physics |
| title | Global simulations of aerosol processing in clouds |
| title_full | Global simulations of aerosol processing in clouds |
| title_fullStr | Global simulations of aerosol processing in clouds |
| title_full_unstemmed | Global simulations of aerosol processing in clouds |
| title_short | Global simulations of aerosol processing in clouds |
| title_sort | global simulations of aerosol processing in clouds |
| url | http://www.atmos-chem-phys.net/8/6939/2008/acp-8-6939-2008.pdf |
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