DOI: 10.1002/2017MS001095
Scopus记录号: 2-s2.0-85041589314
论文题名: A Diagnostic PDF Cloud Scheme to Improve Subtropical Low Clouds in NCAR Community Atmosphere Model (CAM5)
作者: Qin Y ; , Lin Y ; , Xu S ; , Ma H ; -Y ; , Xie S
刊名: Journal of Advances in Modeling Earth Systems
ISSN: 19422466
出版年: 2018
卷: 10, 期: 2 起始页码: 320
结束页码: 341
语种: 英语
英文关键词: Atmospheric humidity
; Boundary layers
; Budget control
; Liquids
; Parameterization
; CAM5
; Community atmosphere model
; Community atmospheric model
; Coupled simulation
; Liquid water content
; Marine boundary layer clouds
; PDF cloud scheme
; Short-term forecasts
; Tropics
; atmospheric modeling
; boundary layer
; condensate
; intertropical convergence zone
; parameterization
; radiation balance
; radiation budget
; simulation
; stratocumulus
; subtropical region
; top of atmosphere
; Pacific Ocean
; Pacific Ocean (Southeast)
英文摘要: Low clouds strongly impact the radiation budget of the climate system, but their simulation in most GCMs has remained a challenge, especially over the subtropical stratocumulus region. Assuming a Gaussian distribution for the subgrid-scale total water and liquid water potential temperature, a new statistical cloud scheme is proposed and tested in NCAR Community Atmospheric Model version 5 (CAM5). The subgrid-scale variance is diagnosed from the turbulent and shallow convective processes in CAM5. The approach is able to maintain the consistency between cloud fraction and cloud condensate and thus alleviates the adjustment needed in the default relative humidity-based cloud fraction scheme. Short-term forecast simulations indicate that low cloud fraction and liquid water content, including their diurnal cycle, are improved due to a proper consideration of subgrid-scale variance over the southeastern Pacific Ocean region. Compared with the default cloud scheme, the new approach produced the mean climate reasonably well with improved shortwave cloud forcing (SWCF) due to more reasonable low cloud fraction and liquid water path over regions with predominant low clouds. Meanwhile, the SWCF bias over the tropical land regions is also alleviated. Furthermore, the simulated marine boundary layer clouds with the new approach extend further offshore and agree better with observations. The new approach is able to obtain the top of atmosphere (TOA) radiation balance with a slightly alleviated double ITCZ problem in preliminary coupled simulations. This study implies that a close coupling of cloud processes with other subgrid-scale physical processes is a promising approach to improve cloud simulations. © 2018. The Authors. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/75649
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: Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, and, Joint Center for Global Change Studies, Tsinghua University, Beijing, China; Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, CA, United States
Recommended Citation:
Qin Y,, Lin Y,, Xu S,et al. A Diagnostic PDF Cloud Scheme to Improve Subtropical Low Clouds in NCAR Community Atmosphere Model (CAM5)[J]. Journal of Advances in Modeling Earth Systems,2018-01-01,10(2)