Improving aerosol effective radiative forcing in E3SM with new cloud microphysics and deep convective wet removal treatments
| Autor: | Fan, Jiwen, Shan, Yunpeng, Zhang, Kai, Shpund, Jacob, Easter, Richard, Wang, Hailong, Zhang, Guang, Song, Xiaoliang, Terai, Ryutaro Christopher, Xie, Shaocheng, Liu, Xiaohong |
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| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Zdroj: | XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) |
| Popis: | Radiative forcing by aerosol-cloud interaction (ACI) remains the largest uncertainty in climate projection based on the IPCC AR6 report in 2021. Many Earth system models tend to overestimate aerosol effective radiative forcing (ERFaer) mainly because of the overly strong ACI forcing, including Department of Energy’s Energy Exascale Earth System Model (E3SM). In the effort to developing E3SM v3, we incorporated a new cloud microphysics scheme - the Predicted Particles Properties (P3) and the improved the deep convective wet removal treatments, aiming at providing better simulations of clouds, radiation, and ACI. We find that comparing with the original Morrison-Gettelman (MG2) scheme, the P3 improves shortwave cloud radiative forcing by over 1 W m-2 and reduces ERFaer by 0.17 W m-2 in global mean. By improving aerosol wet removal treatments for deep convection (e.g., cloud-borne aerosol detrainment, aerosol secondary activation, and cloud-borne aerosol removal), we effectively decrease the overestimation of aerosol burden and lifetime, and reduce the positive biases in aerosol optical depth and aerosol mass concentration. The resultant direct and indirect forcing components of ERFaer are significantly decreased. With some further turning in the minimal cloud droplet number concentrations (Nc), the autoconversion Nc exponent, and the subgrid factor for ice nucleation in cirrus clouds, we can achieve an aerosol forcing of about -0.9 W m-2 which is well within the reference range by IPCC AR6 report. Such effort addresses the outstanding issue of E3SM - unreasonably strong ERFaer, which would help reproduce the global temperature trend since the industrial revolution. The 28th IUGG General Assembly (IUGG2023) (Berlin 2023) |
| Databáze: | OpenAIRE |
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