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    Analysis of Convection and Its Association with African Easterly Waves

    Source: Journal of Climate:;2006:;volume( 019 ):;issue: 020::page 5405
    Author:
    Mekonnen, Ademe
    ,
    Thorncroft, Chris D.
    ,
    Aiyyer, Anantha R.
    DOI: 10.1175/JCLI3920.1
    Publisher: American Meteorological Society
    Abstract: The association between convection and African easterly wave (AEW) activity over tropical Africa and the tropical Atlantic during the boreal summer is examined using satellite brightness temperature (TB) and ECMWF reanalysis datasets. Spectral analysis using 18 yr of TB data shows significant variance in the 2?6-day range across most of the region. Within the regions of deep convection, this time scale accounts for about 25%?35% of the total variance. The 2?6-day convective variance has similar amplitudes over western and eastern Africa, while dynamic measures of AEW activity show stronger amplitudes in the west. This study suggests that weak AEW activity in the east is consistent with initial wave development there and indicates that convection triggered on the western side of the mountains over central and eastern Africa, near Darfur (western Sudan) and Ethiopia, has a role in initiating AEWs westward. The subsequent development and growth of AEWs in West Africa is associated with stronger coherence with convection there. Results show large year-to-year variability in convection at the 2?6-day time scale, which tends to vary consistently with the mean convection and dynamical measures of AEW activity over West Africa and the Atlantic, but not over central and eastern Africa. The Darfur region is particularly important for providing convective precursors that propagate westward and trigger AEWs downstream. During wet years, convection over eastern Africa (western Ethiopian highlands) can be a significant source of AEW initiation. In addition to being important for precursors of AEWs, the Darfur region is also a source of convection that propagates eastward toward Ethiopia.
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      Analysis of Convection and Its Association with African Easterly Waves

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    http://yetl.yabesh.ir/yetl1/handle/yetl/4221048
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    contributor authorMekonnen, Ademe
    contributor authorThorncroft, Chris D.
    contributor authorAiyyer, Anantha R.
    date accessioned2017-06-09T17:02:29Z
    date available2017-06-09T17:02:29Z
    date copyright2006/10/01
    date issued2006
    identifier issn0894-8755
    identifier otherams-78385.pdf
    identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4221048
    description abstractThe association between convection and African easterly wave (AEW) activity over tropical Africa and the tropical Atlantic during the boreal summer is examined using satellite brightness temperature (TB) and ECMWF reanalysis datasets. Spectral analysis using 18 yr of TB data shows significant variance in the 2?6-day range across most of the region. Within the regions of deep convection, this time scale accounts for about 25%?35% of the total variance. The 2?6-day convective variance has similar amplitudes over western and eastern Africa, while dynamic measures of AEW activity show stronger amplitudes in the west. This study suggests that weak AEW activity in the east is consistent with initial wave development there and indicates that convection triggered on the western side of the mountains over central and eastern Africa, near Darfur (western Sudan) and Ethiopia, has a role in initiating AEWs westward. The subsequent development and growth of AEWs in West Africa is associated with stronger coherence with convection there. Results show large year-to-year variability in convection at the 2?6-day time scale, which tends to vary consistently with the mean convection and dynamical measures of AEW activity over West Africa and the Atlantic, but not over central and eastern Africa. The Darfur region is particularly important for providing convective precursors that propagate westward and trigger AEWs downstream. During wet years, convection over eastern Africa (western Ethiopian highlands) can be a significant source of AEW initiation. In addition to being important for precursors of AEWs, the Darfur region is also a source of convection that propagates eastward toward Ethiopia.
    publisherAmerican Meteorological Society
    titleAnalysis of Convection and Its Association with African Easterly Waves
    typeJournal Paper
    journal volume19
    journal issue20
    journal titleJournal of Climate
    identifier doi10.1175/JCLI3920.1
    journal fristpage5405
    journal lastpage5421
    treeJournal of Climate:;2006:;volume( 019 ):;issue: 020
    contenttypeFulltext
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    DSpace software copyright © 2002-2015  DuraSpace
    نرم افزار کتابخانه دیجیتال "دی اسپیس" فارسی شده توسط یابش برای کتابخانه های ایرانی | تماس با یابش
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