Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μm
The optical properties of externally mixed light absorbing carbon (LAC) aggregates are computed over the spectral range from 200 nm–12.2 μm by use of the numerically exact superposition T-matrix method. The spectral computations are tailored to the 14-band radiation model employed in the Integrated...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2010-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/10/8319/2010/acp-10-8319-2010.pdf |
| _version_ | 1818364211032489984 |
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| author | M. Kahnert |
| author_facet | M. Kahnert |
| author_sort | M. Kahnert |
| collection | DOAJ |
| description | The optical properties of externally mixed light absorbing carbon (LAC) aggregates are computed over the spectral range from 200 nm–12.2 μm by use of the numerically exact superposition T-matrix method. The spectral computations are tailored to the 14-band radiation model employed in the Integrated Forecasting System operated at the European Centre for Medium Range Weather Forecast. The size- and wavelength dependence of the optical properties obtained with the fractal aggregate model differs significantly from corresponding results based on the homogeneous sphere approximation, which is still commonly employed in climate models. The computational results are integrated into the chemical transport model MATCH (Multiple-scale Atmospheric Transport and CHemistry modelling system) to compute 3-D fields of size-averaged aerosol optical properties. Computational results obtained with MATCH are coupled to a radiative transfer model to compute the shortwave radiative impact of LAC. It is found that the fractal aggregate model gives a shortwave forcing estimate that is twice as high as that obtained with the homogeneous sphere approximation. Thus previous estimates based on the homogeneous sphere model may have substantially underestimated the shortwave radiative impact of freshly emitted LAC. |
| first_indexed | 2024-12-13T22:00:45Z |
| format | Article |
| id | doaj.art-5d7819c859de4038b7fb417553d89e10 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-13T22:00:45Z |
| publishDate | 2010-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-5d7819c859de4038b7fb417553d89e102022-12-21T23:30:01ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242010-09-0110178319832910.5194/acp-10-8319-2010Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μmM. KahnertThe optical properties of externally mixed light absorbing carbon (LAC) aggregates are computed over the spectral range from 200 nm–12.2 μm by use of the numerically exact superposition T-matrix method. The spectral computations are tailored to the 14-band radiation model employed in the Integrated Forecasting System operated at the European Centre for Medium Range Weather Forecast. The size- and wavelength dependence of the optical properties obtained with the fractal aggregate model differs significantly from corresponding results based on the homogeneous sphere approximation, which is still commonly employed in climate models. The computational results are integrated into the chemical transport model MATCH (Multiple-scale Atmospheric Transport and CHemistry modelling system) to compute 3-D fields of size-averaged aerosol optical properties. Computational results obtained with MATCH are coupled to a radiative transfer model to compute the shortwave radiative impact of LAC. It is found that the fractal aggregate model gives a shortwave forcing estimate that is twice as high as that obtained with the homogeneous sphere approximation. Thus previous estimates based on the homogeneous sphere model may have substantially underestimated the shortwave radiative impact of freshly emitted LAC.http://www.atmos-chem-phys.net/10/8319/2010/acp-10-8319-2010.pdf |
| spellingShingle | M. Kahnert Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μm Atmospheric Chemistry and Physics |
| title | Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μm |
| title_full | Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μm |
| title_fullStr | Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μm |
| title_full_unstemmed | Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μm |
| title_short | Numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm–12.2 μm |
| title_sort | numerically exact computation of the optical properties of light absorbing carbon aggregates for wavelength of 200 nm 12 2 μm |
| url | http://www.atmos-chem-phys.net/10/8319/2010/acp-10-8319-2010.pdf |
| work_keys_str_mv | AT mkahnert numericallyexactcomputationoftheopticalpropertiesoflightabsorbingcarbonaggregatesforwavelengthof200nm122mm |