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)

Ghosh, Pratapaditya; Evans, Katherine J.; Grosvenor, Daniel P.; Kang, Hyun-Gyu; Mahajan, Salil; Xu, Min; Zhang, Wei; Gordon, Hamish

doi:https://doi.org/10.5194/gmd-18-4899-2025

Articles | Volume 18, issue 15

https://doi.org/10.5194/gmd-18-4899-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/gmd-18-4899-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 15

Development and technical paper

|

11 Aug 2025

Development and technical paper |

| 11 Aug 2025

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)

Pratapaditya Ghosh, Katherine J. Evans, Daniel P. Grosvenor, Hyun-Gyu Kang, Salil Mahajan, Min Xu, Wei Zhang, and Hamish Gordon

Supplement

https://doi.org/10.5194/gmd-18-4899-2025-supplement

Data sets

Improving the Abdul-Razzak & Ghan (2000) aerosol activation parameterization impacts simulated cloud radiative effects (shown in the Unified Model, version 13.0) P. Ghosh et al. https://doi.org/10.5281/zenodo.15062206

Daily MODIS (MODerate Imaging Spectroradiometer) derived cloud droplet number concentration global dataset for 2003-2015 D. Grosvenor and R. Wood https://catalogue.ceda.ac.uk/uuid/cf97ccc802d348ec8a3b6f2995dfbbff

Model code and software

Modifying the Abdul-Razzak & Ghan aerosol activation parameterization (version ARG2000) impacts simulated cloud radiative effects (shown in the UK Met Office Unified Model, version 13.0) P. Ghosh et al. https://doi.org/10.5281/zenodo.15062206

metomi/rose: 2019.01.3 M. Shin et al. https://doi.org/10.5281/zenodo.3800775

cylc/cylc-flow: cylc-7.8.8 H. J. Oliver et al. https://doi.org/10.5281/zenodo.4638360

Short summary

The most popular algorithm for calculating cloud droplet number concentrations in climate models is sensitive to parameters that control simulated aerosol particle number concentrations at different sizes. We recommend small modifications to functions in the algorithm to improve its performance. Implementing the changes in the UK Met Office climate model reduced average bias in simulated global droplet number concentrations, leading to more reflected solar radiation and a net cooling effect.