| DOI: | 10.1002/2016MS000713
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| Scopus记录号: | 2-s2.0-84990041458
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| 论文题名: | Diurnal timescale feedbacks in the tropical cumulus regime |
| 作者: | Ruppert J; H; , Jr
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| 刊名: | Journal of Advances in Modeling Earth Systems
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| ISSN: | 19422466
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| 出版年: | 2016
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| 卷: | 8, 期:3 | | 起始页码: | 1483
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| 结束页码: | 1500
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| 语种: | 英语
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| 英文关键词: | Climatology
; Clouds
; Feedback
; Heat convection
; Precipitation (meteorology)
; Wetting
; Climate
; Climate prediction
; Climate variability
; Cloud resolving model
; Cumulus
; Diurnal cycle
; Radiative cooling
; Unstable conditions
; Climate models
; atmospheric convection
; atmospheric moisture
; climate feedback
; climate forcing
; climate modeling
; cloud cover
; cloud radiative forcing
; cumulus
; diurnal variation
; humidity
; optical depth
; precipitation (climatology)
; thermodynamics
; timescale
; tropical region
; troposphere
; warm pool
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| 英文摘要: | Although the importance of the diurnal cycle in modulating clouds and precipitation has long been recognized, its impact on the climate system at longer timescales has remained elusive. Mounting evidence indicates that the diurnal cycle may substantially affect leading climate modes through nonlinear rectification. In this study, an idealized cloud-resolving model experiment is executed to isolate a diurnal timescale feedback in the shallow cumulus regime over the tropical warm pool. This feedback is isolated by modifying the period of the diurnal cycle (or removing it), which proportionally scales (or removes) the diurnal thermodynamic forcing that clouds respond to. This diurnal forcing is identified as covarying cycles of static stability and humidity in the lower troposphere, wherein the most unstable conditions coincide with greatest humidity each afternoon. This diurnal forcing yields deeper clouds and greater daily-mean cumulus heating than would otherwise occur, in turn reducing large-scale subsidence from day to day according to the “weak temperature gradient” approximation. This diurnal forcing therefore manifests as a timescale feedback by accelerating the onset of deep convection. The longwave cloud-radiation effect is found to amplify this timescale feedback, since the resulting invigoration of clouds (increased upper-cloud radiative cooling, with suppressed cooling below) scales with cloud depth (i.e., optical thickness), and hence with the magnitude of diurnal forcing. These findings highlight the pressing need to remedy longstanding problems related to the diurnal cycle in many climate models. Given the evident sensitivity of climate variability to diurnal processes, doing so may yield advances in climate prediction at longer timescales. © 2016. The Authors. |
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| 资源类型: | 期刊论文
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/75877
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| Appears in Collections: | 影响、适应和脆弱性
气候变化与战略
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作者单位: | Max Planck Institute for Meteorology, Hamburg, Germany
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| Recommended Citation: | |
Ruppert J,H,, Jr. Diurnal timescale feedbacks in the tropical cumulus regime[J]. Journal of Advances in Modeling Earth Systems,2016-01-01,8(3)
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