Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0)
<p>The representation of aerosol activation is a key source of uncertainty in global composition-climate model simulations of aerosol–cloud interactions. The Abdul-Razzak and Ghan (ARG) activation parameterization is used in several global and regional models that employ modal aerosol microph...
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Copernicus Publications
2025-08-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/18/4899/2025/gmd-18-4899-2025.pdf |
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| author | P. Ghosh P. Ghosh K. J. Evans D. P. Grosvenor D. P. Grosvenor H.-G. Kang S. Mahajan M. Xu W. Zhang H. Gordon H. Gordon |
| author_facet | P. Ghosh P. Ghosh K. J. Evans D. P. Grosvenor D. P. Grosvenor H.-G. Kang S. Mahajan M. Xu W. Zhang H. Gordon H. Gordon |
| author_sort | P. Ghosh |
| collection | DOAJ |
| description | <p>The representation of aerosol activation is a key source of uncertainty in global composition-climate model simulations of aerosol–cloud interactions. The Abdul-Razzak and Ghan (ARG) activation parameterization is used in several global and regional models that employ modal aerosol microphysics schemes. In this study, we investigate the ability of the ARG parameterization to reproduce simulations with a cloud parcel model and find its performance is sensitive to the geometric standard deviations (widths) of the lognormal aerosol modes. We recommend adjustments to three constant parameters in the ARG equations, which improve the performance of the parameterization for small mode widths and its ability to simulate activation in polluted conditions. For the accumulation mode width of 1.4 used in the Met Office Unified Model (UM), the modifications decrease the mean bias in the activated fraction of aerosols compared to a cloud parcel model from <span class="inline-formula">−6.6</span> % to <span class="inline-formula">+1.2</span> %. We implemented the improvements in the UM and compared simulated global cloud droplet concentrations with satellite observations. The simulated cloud radiative effect changes by <span class="inline-formula">−1.43</span> <span class="inline-formula">W m<sup>−2</sup></span> (<span class="inline-formula">6</span> %) and aerosol indirect radiative forcing over the industrial period changes by <span class="inline-formula">−0.10</span> <span class="inline-formula">W m<sup>−2</sup></span> (<span class="inline-formula">10</span> %).</p> |
| format | Article |
| id | doaj-art-e0846ba4c2ed4915a7233813d8dfc029 |
| institution | Kabale University |
| issn | 1991-959X 1991-9603 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj-art-e0846ba4c2ed4915a7233813d8dfc0292025-08-20T03:39:28ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032025-08-01184899491310.5194/gmd-18-4899-2025Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0)P. Ghosh0P. Ghosh1K. J. Evans2D. P. Grosvenor3D. P. Grosvenor4H.-G. Kang5S. Mahajan6M. Xu7W. Zhang8H. Gordon9H. Gordon10Department of Civil and Environmental Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USACenter for Atmospheric Particle Studies, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USAOak Ridge National Laboratory, Oak Ridge, TN, 37831, USAMet Office Hadley Centre, Exeter, UKSchool of Earth and Environment, University of Leeds, Leeds, UKOak Ridge National Laboratory, Oak Ridge, TN, 37831, USAOak Ridge National Laboratory, Oak Ridge, TN, 37831, USAOak Ridge National Laboratory, Oak Ridge, TN, 37831, USAOak Ridge National Laboratory, Oak Ridge, TN, 37831, USACenter for Atmospheric Particle Studies, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USADepartment of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA<p>The representation of aerosol activation is a key source of uncertainty in global composition-climate model simulations of aerosol–cloud interactions. The Abdul-Razzak and Ghan (ARG) activation parameterization is used in several global and regional models that employ modal aerosol microphysics schemes. In this study, we investigate the ability of the ARG parameterization to reproduce simulations with a cloud parcel model and find its performance is sensitive to the geometric standard deviations (widths) of the lognormal aerosol modes. We recommend adjustments to three constant parameters in the ARG equations, which improve the performance of the parameterization for small mode widths and its ability to simulate activation in polluted conditions. For the accumulation mode width of 1.4 used in the Met Office Unified Model (UM), the modifications decrease the mean bias in the activated fraction of aerosols compared to a cloud parcel model from <span class="inline-formula">−6.6</span> % to <span class="inline-formula">+1.2</span> %. We implemented the improvements in the UM and compared simulated global cloud droplet concentrations with satellite observations. The simulated cloud radiative effect changes by <span class="inline-formula">−1.43</span> <span class="inline-formula">W m<sup>−2</sup></span> (<span class="inline-formula">6</span> %) and aerosol indirect radiative forcing over the industrial period changes by <span class="inline-formula">−0.10</span> <span class="inline-formula">W m<sup>−2</sup></span> (<span class="inline-formula">10</span> %).</p>https://gmd.copernicus.org/articles/18/4899/2025/gmd-18-4899-2025.pdf |
| spellingShingle | P. Ghosh P. Ghosh K. J. Evans D. P. Grosvenor D. P. Grosvenor H.-G. Kang S. Mahajan M. Xu W. Zhang H. Gordon H. Gordon Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0) Geoscientific Model Development |
| title | Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0) |
| title_full | Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0) |
| title_fullStr | Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0) |
| title_full_unstemmed | Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0) |
| title_short | Assessing modifications to the Abdul-Razzak and Ghan aerosol activation parameterization (version ARG2000) to improve simulated aerosol–cloud radiative effects in the UK Met Office Unified Model (UM version 13.0) |
| title_sort | assessing modifications to the abdul razzak and ghan aerosol activation parameterization version arg2000 to improve simulated aerosol cloud radiative effects in the uk met office unified model um version 13 0 |
| url | https://gmd.copernicus.org/articles/18/4899/2025/gmd-18-4899-2025.pdf |
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