DOI: 10.1175/JCLI-D-16-0451.1
Scopus记录号: 2-s2.0-85014031315
论文题名: Why do global climate models struggle to represent low-level clouds in the west african summer monsoon?
作者: Hannak L. ; Knippertz P. ; Fink A.H. ; Kniffka A. ; Pante G.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2017
卷: 30, 期: 5 起始页码: 1665
结束页码: 1687
语种: 英语
Scopus关键词: Atmospheric humidity
; Atmospheric thermodynamics
; Boundary layers
; Fighter aircraft
; Moisture
; Precipitation (meteorology)
; Boundary layer dynamics
; Concomitant effects
; Coupled Model Intercomparison Project
; Global climate model
; Temperature and humidities
; Temperature and relative humidity
; Vertical transports
; West African Monsoon
; Climate models
; climate modeling
; cloud cover
; CMIP
; energy balance
; global climate
; monsoon
; precipitation (climatology)
; relative humidity
; summer
; West Africa
英文摘要: Climate models struggle to realistically represent the West African monsoon (WAM), which hinders reliable future projections and the development of adequate adaption measures. Low-level clouds over southern West Africa (58-108N, 88W-88E) during July-September are an integral part of the WAM through their effect on the surface energy balance and precipitation, but their representation in climate models has received little attention. Here 30 (20) years of output from 18 (8) models participating in phase 5 of the Coupled Model Intercomparison Project (Year of Tropical Convection) are used to identify cloud biases and their causes. Compared to ERA-Interim reanalyses, many models show large biases in low-level cloudiness of both signs and a tendency to too high elevation and too weak diurnal cycles. At the same time, these models tend to have too strong low-level jets, the impact of which is unclear because of concomitant effects on temperature and moisture advection as well as turbulent mixing. Part of the differences between the models and ERA-Interim appear to be related to the different subgrid cloud schemes used. While nighttime tendencies in temperature and humidity are broadly realistic in most models, daytime tendencies show large problems with the vertical transport of heat and moisture. Many models simulate too low near-surface relative humidities, leading to insufficient low cloud cover and abundant solar radiation, and thus a too large diurnal cycle in temperature and relative humidity. In the future, targeted model sensitivity experiments will be needed to test possible feedback mechanisms between low clouds, radiation, boundary layer dynamics, precipitation, and the WAM circulation. © 2017 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49758
Appears in Collections: 气候变化事实与影响
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作者单位: Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
Recommended Citation:
Hannak L.,Knippertz P.,Fink A.H.,et al. Why do global climate models struggle to represent low-level clouds in the west african summer monsoon?[J]. Journal of Climate,2017-01-01,30(5)