DOI: 10.1007/s00382-012-1608-5
Scopus记录号: 2-s2.0-84884703264
论文题名: Coupling between subtropical cloud feedback and the local hydrological cycle in a climate model
作者: Webb M.J. ; Lock A.P.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2013
卷: 41, 期: 2017-07-08 起始页码: 1923
结束页码: 1939
语种: 英语
英文关键词: Boundary layer cloud
; Climate change
; Cloud feedback
; Hydrological cycle
英文摘要: In HadGEM2-A, AMIP experiments forced with observed sea surface temperatures respond to uniform and patterned +4 K SST perturbations with strong positive cloud feedbacks in the subtropical stratocumulus/trade cumulus transition regions. Over the subtropical Northeast Pacific at 137°W/26°N, the boundary layer cloud fraction reduces considerably in the AMIP +4 K patterned SST experiment. The near-surface wind speed and the air-sea temperature difference reduces, while the near-surface relative humidity increases. These changes limit the local increase in surface evaporation to just 3 W/m2 or 0.6 %/K. Previous studies have suggested that increases in surface evaporation may be required to maintain maritime boundary layer cloud in a warmer climate. This suggests that the supply of water vapour from surface evaporation may not be increasing enough to maintain the low level cloud fraction in the warmer climate in HadGEM2-A. Sensitivity tests which force the surface evaporation to increase substantially in the +4 K patterned SST experiment result in smaller changes in boundary layer cloud and a weaker cloud feedback in HadGEM2-A, supporting this idea. Although global mean surface evaporation in climate models increases robustly with global temperature (and the resulting increase in atmospheric radiative cooling), local values may increase much less, having a significant impact on cloud feedback. These results suggest a coupling between cloud feedback and the hydrological cycle via changes in the patterns of surface evaporation. A better understanding of both the factors controlling local changes in surface evaporation and the sensitivity of clouds to such changes may be required to understand the reasons for inter-model differences in subtropical cloud feedback. © 2012 Crown Copyright. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54780
Appears in Collections: 过去全球变化的重建
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作者单位: Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB, United Kingdom
Recommended Citation:
Webb M.J.,Lock A.P.. Coupling between subtropical cloud feedback and the local hydrological cycle in a climate model[J]. Climate Dynamics,2013-01-01,41(2017-07-08)