The Low-Level Structure of African Easterly Waves in 1995
The Low-Level Structure of African Easterly Waves in 1995
复制标题
1995年非洲东波的低层结构
DOI：
--
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
C. Thorncroft
中科院分区：
文献类型：
--
作者：
I. Pytharoulis;C. Thorncroft
利用1995年飓风季节的探空资料和英国气象局的全球模式分析，证实和澄清了非洲东风急流(AEJ)核心以北的非洲东风波(AEW)的存在，其中低层非洲东风波的幅度最大。在巴马科(12.5°N，8.0°W)，AEW的最大波幅主要在AEJ水平(约700 mb)，而在达喀尔(14.7°N，17.5°W)，AEW的最大值出现在850-950 mb之间。急流北侧低层波的产生与急流中心负经向位涡(PV)梯度和位温正低层梯度θ之间的斜压相互作用有关，这种斜压相互作用因急流以北低静稳定空气的存在而得到加强。这些波在北非上空遵循正的经向θ梯度，与在AEJ水平跟随经向PV梯度的急流水平AEW相反。互相关分析..。
Abstract The existence of African easterly waves (AEWs) north of the African easterly jet (AEJ) core with maximum amplitude at low levels has been confirmed and clarified using radiosonde data and the U.K. Meteorological Office global model analysis from the hurricane season of 1995. At Bamako (12.5°N, 8.0°W) the AEWs were characterized mainly by maximum amplitudes at the level of the AEJ (around 700 mb), whereas at Dakar (14.7°N, 17.5°W) the waves were characterized by maxima between 850 and 950 mb. The low-level waves to the north of the AEJ arise in association with baroclinic interactions between the negative meridional potential vorticity (PV) gradients in the jet core and the positive low-level gradient of potential temperature, θ, enhanced by the presence of low-static-stability air north of the AEJ. These waves follow the positive meridional θ gradients over northern Africa in contrast to the jet-level AEWs that follow the meridional PV gradients at the level of the AEJ. Cross-correlation analysis...