DOI: 10.1175/JCLI-D-14-00138.1
Scopus记录号: 2-s2.0-84906885923
论文题名: Effects of orography and surface heat fluxes on the South Asian summer monsoon
作者: Ma D. ; Boos W. ; Kuang Z.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2014
卷: 27, 期: 17 起始页码: 6647
结束页码: 6659
语种: 英语
Scopus关键词: Topography
; Troposphere
; Asian summer monsoons
; Convective equilibriums
; Highly-correlated
; Monsoon strength
; Potential temperature
; Quasi equilibrium
; Surface heat fluxes
; Vertical wind shear
; Atmospheric thermodynamics
英文摘要: A high-resolution (40km horizontal) global model is used to examine controls on the South Asian summer monsoon by orography and surface heat fluxes. In a series of integrations with altered topography and reduced surface heat fluxes, monsoon strength, as indicated by a vertical wind shear index, is highly correlated with the amplitude of the maximum boundary layer equivalent potential temperature (θeb) over South Asia. Removal of the Tibetan Plateau while preserving the Himalayas and adjacent mountain ranges has little effect on monsoon strength, and monsoon strength decreases approximately linearly as the height of the Himalayas is reduced. In terms of surface heat flux changes, monsoon strength is most sensitive to those in the location of the θeb maximum just south of the Himalayas. These results are consistent with the recent idea that topography creates a strong monsoon by insulating the thermal maximum from dry extratropical air. However, monsoon strength is found to be more sensitive to variations in the θeb maximum when topography is altered than when surface heat fluxes are reduced, and it is suggested that free-tropospheric humidity changes lead to deviations from strict convective quasi equilibrium and cause this difference. When topography is reduced, dry extratropical air intrudes into the troposphere over the θeb maximum and is entrained by local deep convection, requiring a higher θeb to achieve convective equilibrium with a given upper-tropospheric temperature and associated balanced monsoon flow. These results illustrate potential complexities that need to be included in simple theories for monsoon strength built on strict convective quasi equilibrium. © 2014 American Meteorological Society. 资助项目: NSF, National Science Foundation
; NSF, National Science Foundation
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/50998
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States; Department of Geology and Geophysics, Yale University, New Haven, CT, United States; Department of Earth and Planetary Sciences, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States
Recommended Citation:
Ma D.,Boos W.,Kuang Z.. Effects of orography and surface heat fluxes on the South Asian summer monsoon[J]. Journal of Climate,2014-01-01,27(17)