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DOI | 10.5194/acp-20-1317-2020 |
Diurnal cycle of the semi-direct effect from a persistent absorbing aerosol layer over marine stratocumulus in large-eddy simulations | |
Herbert, Ross J.1,3; Bellouin, Nicolas1; Highwood, Ellie J.1; Hill, Adrian A.2 | |
2020-02-05 | |
发表期刊 | ATMOSPHERIC CHEMISTRY AND PHYSICS
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ISSN | 1680-7316 |
EISSN | 1680-7324 |
出版年 | 2020 |
卷号 | 20期号:3页码:1317-1340 |
文章类型 | Article |
语种 | 英语 |
国家 | England |
英文摘要 | The rapid adjustment, or semi-direct effect, of marine stratocumulus clouds to elevated layers of absorbing aerosols may enhance or dampen the radiative effect of aerosolradiation interactions. Here we use large-eddy simulations to investigate the sensitivity of stratocumulus clouds to the properties of an absorbing aerosol layer located above the inversion layer, with a focus on the location, timing, and strength of the radiative heat perturbation. The sign of the daily mean semi-direct effect depends on the properties and duration of the aerosol layer, the properties of the boundary layer, and the model setup. Our results suggest that the daily mean semi-direct effect is more elusive than previously assessed. We find that the daily mean semi-direct effect is dominated by the distance between the cloud and absorbing aerosol layer. Within the first 24 h the semi-direct effect is positive but remains under 2 W m(-2) unless the aerosol layer is directly above the cloud. For longer durations, the daily mean semi-direct effect is consistently negative but weakens by 30 %, 60 %, and 95 % when the distance between the cloud and aerosol layer is 100, 250, and 500 m, respectively. Both the cloud response and semi-direct effect increase for thinner and denser layers of absorbing aerosol. Considerable diurnal variations in the cloud response mean that an instantaneous semi-direct effect is unrepresentative of the daily mean and that observational studies may underestimate or overestimate semi-direct effects depending on the observed time of day. The cloud response is particularly sensitive to the mixing state of the boundary layer: well-mixed boundary layers generally result in a negative daily mean semi-direct effect, and poorly mixed boundary layers result in a positive daily mean semi-direct effect. The properties of the boundary layer and model setup, particularly the sea surface temperature, precipitation, and properties of the air entrained from the free troposphere, also impact the magnitude of the semi-direct effect and the timescale of adjustment. These results suggest that the semi-direct effect simulated by coarse-resolution models may be erroneous because the cloud response is sensitive to small-scale processes, especially the sources and sinks of buoyancy. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000512999100001 |
WOS关键词 | LOWER-TROPOSPHERIC STABILITY ; SOUTH-EAST ATLANTIC ; MIXED-PHASE CLOUDS ; SMOKE ; IMPACT ; MODEL ; TRANSITIONS ; PREDICTION ; TRANSPORT ; MOISTURE |
WOS类目 | Environmental Sciences ; Meteorology & Atmospheric Sciences |
WOS研究方向 | Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/278599 |
专题 | 地球科学 |
作者单位 | 1.Univ Reading, Dept Meteorol, Reading RG6 6BB, Berks, England; 2.Met Off, Fitzroy Rd, Exeter EX1 3PB, Devon, England; 3.Univ Oxford, Dept Phys, Oxford OX1 3PU, England |
推荐引用方式 GB/T 7714 | Herbert, Ross J.,Bellouin, Nicolas,Highwood, Ellie J.,et al. Diurnal cycle of the semi-direct effect from a persistent absorbing aerosol layer over marine stratocumulus in large-eddy simulations[J]. ATMOSPHERIC CHEMISTRY AND PHYSICS,2020,20(3):1317-1340. |
APA | Herbert, Ross J.,Bellouin, Nicolas,Highwood, Ellie J.,&Hill, Adrian A..(2020).Diurnal cycle of the semi-direct effect from a persistent absorbing aerosol layer over marine stratocumulus in large-eddy simulations.ATMOSPHERIC CHEMISTRY AND PHYSICS,20(3),1317-1340. |
MLA | Herbert, Ross J.,et al."Diurnal cycle of the semi-direct effect from a persistent absorbing aerosol layer over marine stratocumulus in large-eddy simulations".ATMOSPHERIC CHEMISTRY AND PHYSICS 20.3(2020):1317-1340. |
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