DOI: 10.1002/jgrd.50394
论文题名: Climatology of nocturnal low-level jets over North Africa and implications for modeling mineral dust emission
作者: Fiedler S. ; Schepanski K. ; Heinold B. ; Knippertz P. ; Tegen I.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 12 起始页码: 6100
结束页码: 6121
语种: 英语
英文关键词: diurnal cycle
; dust emission
; ERA-Interim reanalysis
; Harmattan
; nocturnal low-level jet
; Saharan heat low
Scopus关键词: Atmospheric movements
; Climatology
; Signal detection
; Weather forecasting
; Wind effects
; Diurnal cycle
; Dust emission
; Harmattan
; Heat low
; Nocturnal low-level jets
; Reanalysis
; Dust
; algorithm
; assessment method
; atmospheric pollution
; climate modeling
; climatology
; diurnal variation
; dust
; emission
; frequency analysis
; momentum
; turbulence
; Sahara
英文摘要: This study presents the first climatology for the dust emission amount associated with Nocturnal Low-Level Jets (NLLJs) in North Africa. These wind speed maxima near the top of the nocturnal boundary layer can generate near-surface peak winds due to shear-driven turbulence in the course of the night and the NLLJ breakdown during the following morning. The associated increase in the near-surface wind speed is a driver for mineral dust emission. A new detection algorithm for NLLJs is presented and used for a statistical assessment of NLLJs in 32 years of ERA-Interim reanalysis from the European Centre for Medium-Range Weather Forecasts. NLLJs occur in 29% of the nights in the annual and spatial mean. The NLLJ climatology shows a distinct annual cycle with marked regional differences. Maxima of up to 80% NLLJ frequency are found where low-level baroclinicity and orographic channels cause favorable conditions, e.g., over the Bodélé Depression, Chad, for November-February and along the West Saharan and Mauritanian coast for April-September. Downward mixing of NLLJ momentum to the surface causes 15% of mineral dust emission in the annual and spatial mean and can be associated with up to 60% of the total dust amount in specific areas, e.g., the Bodélé Depression and south of the Hoggar-Tibesti Channel. The sharp diurnal cycle underlines the importance of using wind speed information with high temporal resolution as driving fields for dust emission models. Key Points Long-term climatology of Nocturnal Low-Level Jets (NLLJ) over North Africa Newly developed automated detection algorithm for NLLJs NLLJs contribute 15 % to North African dust emission in annual and spatial mean © 2013. American Geophysical Union. All Rights Reserved. 资助项目: 257543
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63640
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom; Leibniz Institute for Tropospheric Research, Leipzig, Germany
Recommended Citation:
Fiedler S.,Schepanski K.,Heinold B.,et al. Climatology of nocturnal low-level jets over North Africa and implications for modeling mineral dust emission[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(12)