干旱区生态环境知识资源中心(Arid): Role of Easterly Waves in the Maintenance of the African Easterly Jet.

Arid

报告编号	N20000072442
	Role of Easterly Waves in the Maintenance of the African Easterly Jet.
	Ferreira, R. N; Suarez, M; Bacmeister, J.
英文摘要	About fifty percent of all hurricanes in the Atlantic Ocean form within African easterly waves (AEW). Many previous studies have indicated that these waves result from combined barotropic-baroclinic instability of the African Easterly Jet (AEJ). The AEJ is in turn believed to be due to the strong temperature gradient between the very warm Sahara Desert and the cooler Sahel and Gulf of Guinea to the south. Zonally averaged latitude-pressure cross-sections of summertime zonal winds over Africa show the AEJ as a 8-12 m/s jet centered at 600-700 mb near 15 N. Such cross-sections also show a weaker southern hemisphere easterly jet near 5-150S, monsoonal westerlies centered beneath the AEJ, and upper tropospheric features such as the Tropical Easterly Jet (TEJ) near 30N and the subtropical westerly jet near 35ON . Thomcroft and Blackburn performed zonally symmetric simulations that showed that the effect of thermal wind balance over the observed low level meridional temperature gradient over northern Africa is particularly important in the formation of the AEJ. They also found that in order to reproduce some of the other aforementioned features of the summertime climatological wind field over Africa it is necessary to include the effects of Inter-Tropical Convergence Zone (ITCZ) convective heating. While the diabatic effects of Saharan and ITCZ heating tend to strengthen the AEJ, AEW remove energy from the AEJ, thereby weakening it. In this study we take the next step towards understanding the maintenance of the AEJ by including the effects of AEW.
英文关键词	Atmospheric circulation Baroclinic instability Hurricanes Temperature gradients Wind(Meteorology) Wind effects Intertropical convergent zones Climate models Sahara desert(Africa) Africa Tropical regions Heat transfer
出版年	2000
语种	英语
国家	美国
URL	http://r.cnki.net/KCMS/detail/detail.aspx?DbCode=KJBG&dbname=KJBGW&filename=59fac06631c97d1d549b004d
来源机构	National Aeronautics and Space Administration
资源类型	科技报告
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/272872
推荐引用方式 GB/T 7714	Ferreira, R. N,Suarez, M,Bacmeister, J.. Role of Easterly Waves in the Maintenance of the African Easterly Jet.,2000.