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contributor authorPeyrillé, Philippe
contributor authorLafore, Jean-Philippe
date accessioned2017-06-09T16:54:05Z
date available2017-06-09T16:54:05Z
date copyright2007/08/01
date issued2007
identifier issn0022-4928
identifier otherams-76222.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4218646
description abstractThe idealized 2D model developed in Part I of this study is used to study the West African monsoon sensitivity to large-scale forcing. Using ECWMF reanalyses, a large-scale forcing is introduced in the 2D model in terms of temperature and humidity advection. A coherent structure of cooling?moistening near the surface and drying?warming in the 2?4-km layer is found in the Saharan heat low region. The effect of the advective forcing is to block the monsoon propagation by strengthening the northerly flux and by an increase of convective inhibition. The heat low thus appears to play a key role in the monsoon northward penetration through its temperature and humidity budget. Ultimately, warmer low levels and/or more moist midlevels in the heat low favor a more northerly position of the ITCZ. A detailed view of the continental diurnal cycle is also presented. Potential temperature and humidity budgets are performed in the deep convective and heat low area. The moistening process to sustain deep convection is made through nocturnal advection at low levels and daytime turbulence that redistributes humidity vertically. The same mechanism occurs in the heat low except that the vertical transfers by turbulence help maintain the dryness of the low levels. A possible mechanism of interaction between the deep convective zone and the Saharan heat low is also proposed that involves gravity waves in the upper troposphere.
publisherAmerican Meteorological Society
titleAn Idealized Two-Dimensional Framework to Study the West African Monsoon. Part II: Large-Scale Advection and the Diurnal Cycle
typeJournal Paper
journal volume64
journal issue8
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/JAS4052.1
journal fristpage2783
journal lastpage2803
treeJournal of the Atmospheric Sciences:;2007:;Volume( 064 ):;issue: 008
contenttypeFulltext


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