DOI: 10.1007/s00382-017-3796-5
Scopus记录号: 2-s2.0-85023776541
论文题名: The influence of extratropical cloud phase and amount feedbacks on climate sensitivity
作者: Frey W.R. ; Kay J.E.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2018
卷: 50, 期: 2018-07-08 起始页码: 3097
结束页码: 3116
语种: 英语
英文关键词: Climate sensitivity
; Cloud feedback
; Greenhouse gas forcing
; Ocean heat uptake
Scopus关键词: climate forcing
; climate modeling
; cloud
; extratropical environment
; global climate
; greenhouse gas
; sea surface
; shortwave radiation
; warming
; Southern Ocean
英文摘要: Global coupled climate models have large long-standing cloud and radiation biases, calling into question their ability to simulate climate and climate change. This study assesses the impact of reducing shortwave radiation biases on climate sensitivity within the Community Earth System Model (CESM). The model is modified by increasing supercooled cloud liquid to better match absorbed shortwave radiation observations over the Southern Ocean while tuning to reduce a compensating tropical shortwave bias. With a thermodynamic mixed-layer ocean, equilibrium warming in response to doubled CO2 increases from 4.1 K in the control to 5.6 K in the modified model. This 1.5 K increase in equilibrium climate sensitivity is caused by changes in two extratropical shortwave cloud feedbacks. First, reduced conversion of cloud ice to liquid at high southern latitudes decreases the magnitude of a negative cloud phase feedback. Second, warming is amplified in the mid-latitudes by a larger positive shortwave cloud feedback. The positive cloud feedback, usually associated with the subtropics, arises when sea surface warming increases the moisture gradient between the boundary layer and free troposphere. The increased moisture gradient enhances the effectiveness of mixing to dry the boundary layer, which decreases cloud amount and optical depth. When a full-depth ocean with dynamics and thermodynamics is included, ocean heat uptake preferentially cools the mid-latitude Southern Ocean, partially inhibiting the positive cloud feedback and slowing warming. Overall, the results highlight strong connections between Southern Ocean mixed-phase cloud partitioning, cloud feedbacks, and ocean heat uptake in a climate forced by greenhouse gas changes. © 2017, Springer-Verlag GmbH Germany. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109378
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Cooperative Institute for Research in Environmental Sciences (CIRES) and Department of Atmospheric and Oceanic Sciences (ATOC), University of Colorado Boulder, 216 UCB, Boulder, CO 80309, United States
Recommended Citation:
Frey W.R.,Kay J.E.. The influence of extratropical cloud phase and amount feedbacks on climate sensitivity[J]. Climate Dynamics,2018-01-01,50(2018-07-08)