Examining Cloud Feedback Components in the Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM).
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| Title: | Examining Cloud Feedback Components in the Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM). |
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| Authors: | Chao, Li-Wei1 (AUTHOR) chao5@llnl.gov, Zelinka, Mark D.1 (AUTHOR), Terai, Christopher R.1 (AUTHOR), Beydoun, Hassan1 (AUTHOR), Hillman, Benjamin R.2 (AUTHOR), Keen, Noel D.3 (AUTHOR), Caldwell, Peter M.1 (AUTHOR), Bogenschutz, Peter A.1 (AUTHOR), Klein, Stephen A.1 (AUTHOR) |
| Source: | Journal of Climate. May2026, Vol. 39 Issue 10, p1-16. 16p. |
| Subjects: | Climate change models, Atmospheric models, Climate change, Cloudiness, Climate sensitivity |
| Abstract: | Cloud feedback remains the main source of uncertainty in climate sensitivity estimated by global climate models (GCMs), largely because sub-grid cloud responses are parameterized in GCMs due to their coarse resolution. This study examines cloud feedback in the global 3.25-km Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM 3km) through a pair of one-year atmosphere-only simulations with control and +4K sea surface temperature perturbations. SCREAM 3km produces a positive cloud feedback that falls within but at the upper end of the range of CMIP5 and CMIP6 models and expert judgment. The positive cloud feedback arises from positive contributions from both high- and low-level clouds, with increases in high cloud altitude and decreases in low cloud amount and optical depth playing key roles. The stronger-than-CMIP-average feedback is mainly attributable to the high-cloud altitude feedback, owing to cloud tops rising nearly isothermally in SCREAM 3km. The positive low-cloud amount feedback is weaker in SCREAM than in GCMs because estimated inversion strength (EIS) increases more dramatically with warming. A coarser 12km resolution version of SCREAM exhibits a weaker positive cloud feedback than SCREAM 3km, mainly because its low-cloud radiative flux is more sensitive to EIS, leading to a stronger negative low-cloud amount feedback. With this process-level assessment of cloud feedback, this study reveals where SCREAM aligns with and diverges from conventional GCMs and expert assessment, providing insights to inform further model improvement and future expert assessment. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Cloud feedback remains the main source of uncertainty in climate sensitivity estimated by global climate models (GCMs), largely because sub-grid cloud responses are parameterized in GCMs due to their coarse resolution. This study examines cloud feedback in the global 3.25-km Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM 3km) through a pair of one-year atmosphere-only simulations with control and +4K sea surface temperature perturbations. SCREAM 3km produces a positive cloud feedback that falls within but at the upper end of the range of CMIP5 and CMIP6 models and expert judgment. The positive cloud feedback arises from positive contributions from both high- and low-level clouds, with increases in high cloud altitude and decreases in low cloud amount and optical depth playing key roles. The stronger-than-CMIP-average feedback is mainly attributable to the high-cloud altitude feedback, owing to cloud tops rising nearly isothermally in SCREAM 3km. The positive low-cloud amount feedback is weaker in SCREAM than in GCMs because estimated inversion strength (EIS) increases more dramatically with warming. A coarser 12km resolution version of SCREAM exhibits a weaker positive cloud feedback than SCREAM 3km, mainly because its low-cloud radiative flux is more sensitive to EIS, leading to a stronger negative low-cloud amount feedback. With this process-level assessment of cloud feedback, this study reveals where SCREAM aligns with and diverges from conventional GCMs and expert assessment, providing insights to inform further model improvement and future expert assessment. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 08948755 |
| DOI: | 10.1175/JCLI-D-25-0656.1 |
