DOI: 10.1002/jgrd.50667
论文题名: Recent changes in air temperature, heat waves occurrences, and atmospheric circulation in Northern Africa
作者: Fontaine B. ; Janicot S. ; Monerie P.-A.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 15 起始页码: 8536
结束页码: 8552
语种: 英语
英文关键词: African monsoon
; Climate Change
; Heat waves
Scopus关键词: Atmospheric temperature
; Atmospheric thermodynamics
; Climate change
; Light velocity
; Moisture
; African easterly jet
; African monsoons
; Anticyclonic anomalies
; Atmospheric circulation
; Atmospheric moisture
; Heat waves
; Long-term evolution
; Temperature anomaly
; Mechanical waves
; air temperature
; anticyclone
; atmospheric circulation
; baroclinic mode
; climate change
; heat flow
; monsoon
; Rossby wave
; temperature anomaly
; Arabian Peninsula
; Atlantic Ocean
; Atlantic Ocean (North)
; Libyan Arab Jamahiriya
; Morocco
; Sahara
; Sahel [Sub-Saharan Africa]
; Western Sahara
英文摘要: This study documents the time evolution of air temperature and heat waves occurrences over Northern Africa for the period 1979-2011. A significant warming (1°-3°C), appearing by the mid-1960s over Sahara and Sahel, is associated with higher/lesser frequency of warm/cold temperatures, as with longer duration and higher occurrences of heat waves. Heat waves episodes of at least 4 day duration have been examined after removing the long-term evolution. These episodes are associated with specific anomalies: (i) in spring, positive low-level temperature anomalies over the Sahel and Sahara; low and midlevel cyclonic rotation over Morocco associated with a Rossby wave pattern, lessening the Harmattan; more/less atmospheric moisture westward/eastward to 0°; upward/downward anomalies above the western/eastern regions associated with the Rossby wave pattern; (ii) in summer, a similar but weaker positive low-level temperature anomaly (up to 3°C); less moisture westward to 10°W, a cyclonic anomaly in central Sahel favoring the monsoon eastward to 0° and a midlevel anticyclonic anomaly over the Western Sahara, increasing southward the flux divergence associated with the African Easterly Jet. In March-May, two to three heat waves propagate eastward. They are preceded by an abnormal warm cell over Libya and southwesterlies over the West Sahara. A large trough stands over North Atlantic while midtropospheric subsidence and anticyclonic rotation reinforce over the continent, then migrates toward the Arabian peninsula in breaking up. These signals are spatially coherent and might suggest the role of short Rossby waves with an eastward group velocity and a baroclinic mode, possibly associated with jet stream deformation. Key Points Longer duration higher occurrences of heat waves 1979-2011(statistics provided) Associated with specific anomalies (described in the manuscript) Suggest short Rossby waves with eastward group velocity + baroclinic mode ©2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63426
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: Centre de Recherches de Climatologie, UMR Biogéosiences, CNRS/Université de Bourgogne, F21000 Dijon, France; IRD, LOCEAN/IPSL, UPMC, Paris, France
Recommended Citation:
Fontaine B.,Janicot S.,Monerie P.-A.. Recent changes in air temperature, heat waves occurrences, and atmospheric circulation in Northern Africa[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(15)