DOI: 10.1175/JCLI-D-16-0295.1
Scopus记录号: 2-s2.0-85001129201
论文题名: Understanding the varied influence of midlatitude jet position on clouds and cloud radiative effects in observations and global climate models
作者: Grise K.M. ; Medeiros B.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2016
卷: 29, 期: 24 起始页码: 9005
结束页码: 9025
语种: 英语
Scopus关键词: Atmospheric pressure
; Boundary layers
; Jets
; Oceanography
; Radiation effects
; Storms
; Velocity
; Annular mode
; Climate variability
; Cloud forcing
; General circulation model
; North Atlantic oscillations
; Climate models
英文摘要: This study examines the dynamical mechanisms responsible for changes in midlatitude clouds and cloud radiative effects (CRE) that occur in conjunction with meridional shifts in the jet streams over the North Atlantic, North Pacific, and Southern Oceans. When the midlatitude jet shifts poleward, extratropical cyclones and their associated upward vertical velocity anomalies closely follow. As a result, a poleward jet shift contributes to a poleward shift in high-topped storm-track clouds and their associated longwave CRE. However, when the jet shifts poleward, downward vertical velocity anomalies increase equatorward of the jet, contributing to an enhancement of the boundary layer estimated inversion strength (EIS) and an increase in low cloud amount there. Because shortwave CRE depends on the reflection of solar radiation by clouds in all layers, the shortwave cooling effects of midlatitude clouds increase with both upward vertical velocity anomalies and positive EIS anomalies. Over midlatitude oceans where a poleward jet shift contributes to positive EIS anomalies but downward vertical velocity anomalies, the two effects cancel, and net observed changes in shortwave CRE are small. Global climate models generally capture the observed anomalies associated with midlatitude jet shifts. However, there is large intermodel spread in the shortwave CRE anomalies, with a subset of models showing a large shortwave cloud radiative warming over midlatitude oceans with a poleward jet shift. In these models, midlatitude shortwave CRE is sensitive to vertical velocity perturbations, but the observed sensitivity to EIS perturbations is underestimated. Consequently, these models might incorrectly estimate future midlatitude cloud feedbacks in regions where appreciable changes in both vertical velocity and EIS are projected. © 2016 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/50292
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Environmental Sciences, University of Virginia, Charlottesville, VA, United States; National Center for Atmospheric Research, Boulder, CO, United States
Recommended Citation:
Grise K.M.,Medeiros B.. Understanding the varied influence of midlatitude jet position on clouds and cloud radiative effects in observations and global climate models[J]. Journal of Climate,2016-01-01,29(24)