DOI: 10.1175/2011JCLI4241.1
Scopus记录号: 2-s2.0-84858253815
论文题名: African easterly jet: Barotropic instability, waves, and cyclogenesis
作者: Wu M.-L.C. ; Reale O. ; Schubert S.D. ; Suarez M.J. ; Thorncroft C.D.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2012
卷: 25, 期: 5 起始页码: 1489
结束页码: 1510
语种: 英语
Scopus关键词: Africa
; African easterly jet
; African easterly waves
; Barotropic
; Cyclogenesis
; Cyclogenesis/cyclolysis
; Data sets
; Extratropical
; Forcings
; Global precipitation climatology projects
; Hilbert Huang transforms
; Instability condition
; Mean flow
; Reanalysis
; Research and application
; Retrospective analysis
; Sea surface temperature (SST)
; Seasonal mean
; Seasonal precipitations
; Tropical cyclogenesis
; Tropical cyclone
; Tropical storms
; Vertical shear
; Atmospheric movements
; Atmospherics
; Jets
; Precipitation (chemical)
; Spectrum analysis
; Tropics
; Waves
; Shear flow
; atmospheric circulation
; atmospheric structure
; barotropic instability
; climate forcing
; cyclogenesis
; easterly wave
; jet flow
; monsoon
; sea surface temperature
; spectral analysis
; storm
; transform
; Africa
; Atlantic Ocean
; Atlantic Ocean (Tropical)
英文摘要: This study investigates the structure of the African easterly jet, focusing on instability processes on a seasonal and subseasonal scale, with the goal of identifying features that could provide increased predictability of Atlantic tropical cyclogenesis. The Modern-Era Retrospective Analysis for Research and Applications (MERRA) is used as the main investigating tool. MERRA is compared with other reanalyses datasets from major operational centers around the world and was found to describe very effectively the circulation over the African monsoon region. In particular, a comparison with precipitation datasets from the Global Precipitation Climatology Project shows that MERRA realistically reproduces seasonal precipitation over that region. The verification of the generalized Kuo barotropic instability condition computed from seasonal means is found to have the interesting property of defining well the location where observed tropical storms are detected. This property does not appear to be an artifact of MERRA and is present also in the other adopted reanalysis datasets. Therefore, the fact that the areas where the mean flow is unstable seems to provide a more favorable environment for wave intensification, could be another factor to include-in addition to sea surface temperature, vertical shear, precipitation, the role of Saharan air, and others-among large-scale forcings affecting development and tropical cyclone frequency. In addition, two prominent modes of variability are found based on a spectral analysis that uses the Hilbert-Huang transform: a 2.5-6-day mode that corresponds well to the African easterly waves and also a 6-9-day mode that seems to be associated with tropical- extratropical interaction. © 2012 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/52502
Appears in Collections: 气候变化事实与影响
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作者单位: Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, United States; Laboratory for Atmospheres, NASA Goddard Space Flight Center, Greenbelt, MD, United States; Department of Earth and Atmospheric Sciences, University at Albany, State University of New York, Albany, NY, United States; Goddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia, MD, United States
Recommended Citation:
Wu M.-L.C.,Reale O.,Schubert S.D.,et al. African easterly jet: Barotropic instability, waves, and cyclogenesis[J]. Journal of Climate,2012-01-01,25(5)