Dynamical mechanisms controlling the vertical redistribution of dust and the thermodynamic structure of the West Saharan atmospheric boundary layer during summer

The Saharan atmospheric boundary layer (SABL) plays a significant role in the atmospheric global circulation and directly affects the vertical redistribution of dust originated in the Sahara, the world's largest dust source. Recent measurements have revealed a variety of new dynamical mechanisms that control the structure of the SABL, which are responsible for exchange between the Saharan convective and residual boundary layers. Using new space-borne laser remote sensing data (CALIPSO) and recently published results, we provide an overview of the following known dynamical mechanisms: diurnal vertical mixing, dynamical lifting (density currents and cold air outbreaks) and topographic effects (mountains and albedo anomalies). Copyright © 2009 Royal Meteorological Society

[1]  Jacques Pelon,et al.  Airborne observations of the impact of a convective system on the planetary boundary layer thermodynamics and aerosol distribution in the inter‐tropical discontinuity region of the West African Monsoon , 2007 .

[2]  O. Torres,et al.  Incorporating the effect of small‐scale circulations upon dust emission in an atmospheric general circulation model , 2004 .

[3]  P. Drobinski,et al.  On the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali , 2009 .

[4]  W. Tian,et al.  Two‐dimensional simulation of orographic effects on mesoscale boundary‐layer convection , 2002 .

[5]  E. Kraus.  Synoptic and dynamic aspects of climatic change , 1960 .

[6]  Observations of mesoscale and boundary-layer circulations affecting dust uplift and transport in the Saharan boundary layer , 2008 .

[7]  Jacques Pelon,et al.  Observational Evidence And Modelling Of An Internal Hydraulic Jump At The Atmospheric Boundary-Layer Top During A Tramontane Event , 2001 .

[8]  M. Gamo,et al.  Thickness of the dry convection and large-scale subsidence above deserts , 1996 .

[9]  Richard Washington,et al.  Dust and the low‐level circulation over the Bodélé Depression, Chad: Observations from BoDEx 2005 , 2006 .

[10]  O. Dubovik,et al.  Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations , 2005 .

[11]  Y. Shao.  Physics and Modelling of Wind Erosion , 2001 .

[12]  Benjamin M. Herman,et al.  Determination of aerosol height distributions by lidar , 1972 .

[13]  M. Mimouni,et al.  Multiplatform observations of the seasonal evolution of the Saharan atmospheric boundary layer in Tamanrasset, Algeria, in the framework of the African Monsoon Multidisciplinary Analysis field campaign conducted in 2006 , 2008 .

[14]  B. Hoskins,et al.  On the use and significance of isentropic potential vorticity maps , 2007 .

[15]  D. Parker.  The response of CAPE and CIN to tropospheric thermal variations , 2002 .

[16]  V. M. Karyampudi,et al.  Analysis and Numerical Simulations of the Saharan Air Layer and Its Effect on Easterly Wave Disturbances , 1988 .

[17]  J. Reid,et al.  Haboob dust storms of the southern Arabian Peninsula , 2008 .

[18]  W. Grey,et al.  Observations of mesoscale and boundary-layer scale circulations affecting dust transport and uplift over the Sahara , 2008 .

[19]  Richard Washington,et al.  North African dust emissions and transport , 2006 .

[20]  Christian M. Grams,et al.  Uplift of Saharan dust south of the intertropical discontinuity , 2008 .

[21]  P. Baines,et al.  Topographic Effects in Stratified Flows , 1995 .

[22]  Peter Knippertz,et al.  Dust emissions in the West African heat trough the role of the diurnal cycle and of extratropical disturbances , 2008 .

[23]  M. Wendisch,et al.  Dust mobilization and transport in the northern Sahara during SAMUM 2006 – a meteorological overview , 2009 .

[24]  Alan H. Strahler,et al.  MODIS bidirectional reflectance distribution function and albedo Climate Modeling Grid products and the variability of albedo for major global vegetation types , 2005 .

[25]  N. Renno,et al.  The role of convective plumes and vortices on the global aerosol budget , 2004 .

[26]  R. Arritt,et al.  Nonclassical mesoscale circulations caused by surface sensible heat-flux gradients , 1992 .

[27]  Masaru Chiba,et al.  A numerical study of the contributions of dust source regions to the global dust budget , 2006 .

[28]  Jacques Pelon,et al.  Dust emissions over the Sahel associated with the West African monsoon intertropical discontinuity region: A representative case‐study , 2008 .

[29]  Andreas H. Fink,et al.  Synoptic and dynamic aspects of an extreme springtime Saharan dust outbreak , 2006 .

[30]  D. Winker,et al.  Initial performance assessment of CALIOP , 2007 .

[31]  C. Mann,et al.  A Practical Treatise on Diseases of the Skin , 1889, Atlanta Medical and Surgical Journal (1884).

[32]  C. Thorncroft,et al.  Analysis of the African easterly jet, using aircraft observations from the JET2000 experiment , 2005 .

[33]  R. Scorer.  Theory of airflow over mountains: IV-separation of flow from the surface , 1955 .

[34]  R. Hamilton,et al.  Meteorology of Nigeria and adjacent territory , 1945 .

[35]  Geert Sterk,et al.  Causes, consequences and control of wind erosion in Sahelian Africa: a review , 2003 .

[36]  Konrad Kandler,et al.  Dust mobilization due to density currents in the Atlas region: Observations from the Saharan Mineral Dust Experiment 2006 field campaign , 2007 .

[37]  R. R. Burton,et al.  The diurnal cycle of the West African monsoon circulation , 2005 .

[38]  H. Maring,et al.  Dust vertical distribution in the Caribbean during the Puerto Rico Dust Experiment , 2002 .

[39]  Jean-Pierre Chaboureau,et al.  Diurnal cycle of dust and cirrus over West Africa as seen from Meteosat Second Generation satellite and a regional forecast model , 2007 .

[40]  Martin Mork,et al.  Topographic effects in stratified flows resolved by a spectral method , 1993 .

[41]  S. Nicholson,et al.  The diurnal and seasonal cycles of wind-borne dust over Africa North of the Equator , 1997 .