Meteorological processes forcing Saharan dust emission inferred from MSG-SEVIRI observations of subdaily dust source activation and numerical models

Fifteen-minute Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) infrared dust index images are used to identify dust source areas. The observations of dust source activation (DSA) are compiled in a 1° × 1° map for the Sahara and Sahel, including temporal information at 3-hourly resolution. Here we use this data set to identify the most active dust source areas and the time of day when dust source activation occurs most frequently. In the Sahara desert 65% of DSA (March 2006 to February 2008) occurs during 0600-0900 UTC, pointing toward an important role of the breakdown of the nocturnal low-level jet (LLJ) for dust mobilization. Other meteorological mechanisms may lead to dust mobilization including density currents initiated by deep convective systems which mobilize dust fronts (haboobs) occurring preferentially in the afternoon hours and cyclonic activities. The role of the nocturnal LLJ for dust mobilization in the Sahara is corroborated by regional model studies and analysis of meteorological station data.

[1]  A. Ansmann,et al.  Regional Saharan dust modelling during the SAMUM 2006 campaign , 2009 .

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

[3]  Jim Haywood,et al.  Modeled and observed atmospheric radiation balance during the West African dry season: Role of mineral dust, biomass burning aerosol, and surface albedo , 2008 .

[4]  Jacques Pelon,et al.  The 7–13 March 2006 dust storm over West Africa: Generation, transport, and vertical stratification , 2008 .

[5]  N. Mahowald,et al.  Modeling mineral dust emissions from the Sahara desert using new surface properties and soil database , 2008 .

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

[7]  Richard Washington,et al.  Regional Model Simulations of the Bodélé Low-Level Jet of Northern Chad during the Bodélé Dust Experiment (BoDEx 2005) , 2008 .

[8]  P. Levelt,et al.  Aerosols and surface UV products from Ozone Monitoring Instrument observations: An overview , 2007 .

[9]  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 .

[10]  K. Schepanski,et al.  A new Saharan dust source activation frequency map derived from MSG‐SEVIRI IR‐channels , 2007 .

[11]  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 .

[12]  Albert Ansmann,et al.  Regional modeling of Saharan dust events using LM-MUSCAT: Model description and case studies , 2007 .

[13]  Richard Washington,et al.  Atmospheric controls on the annual cycle of North African dust , 2007 .

[14]  Thorsten Mauritsen,et al.  Observations of Stably Stratified Shear-Driven Atmospheric Turbulence at Low and High Richardson Numbers , 2007 .

[15]  S. Solomon.  The Physical Science Basis : Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[16]  O. Edenhofer,et al.  Mitigation from a cross-sectoral perspective , 2007 .

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

[18]  Robert M. Banta,et al.  Turbulent Velocity-Variance Profiles in the Stable Boundary Layer Generated by a Nocturnal Low-Level Jet , 2006 .

[19]  Z. Sorbjan.  Local Structure of Turbulence in Stably Stratified Boundary Layers , 2006 .

[20]  C. Flamant,et al.  Links between topography, wind, deflation, lakes and dust: The case of the Bodélé Depression, Chad , 2006 .

[21]  Ranka,et al.  A numerical study of the first phase of a deep Mediterranean cyclone : Cyclogenesis in the lee of the Atlas Mountains , 2006 .

[22]  N. Mahowald,et al.  Atmospheric global dust cycle and iron inputs to the ocean , 2005 .

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

[24]  A. Sterl,et al.  The ERA‐40 re‐analysis , 2005 .

[25]  Richard Washington,et al.  Atmospheric controls on mineral dust emission from the Bodélé Depression, Chad: The role of the low level jet , 2005 .

[26]  Peter Knippertz,et al.  Tropical plumes and extreme precipitation in subtropical and tropical West Africa , 2005 .

[27]  P. Alpert,et al.  Synoptics of dust transportation days from Africa toward Italy and central Europe , 2005 .

[28]  N. Mahowald,et al.  Global Iron Connections Between Desert Dust, Ocean Biogeochemistry, and Climate , 2005, Science.

[29]  C. Medaglia,et al.  A Numerical Study , 2005 .

[30]  Michael D. King,et al.  Aerosol properties over bright-reflecting source regions , 2004, IEEE Transactions on Geoscience and Remote Sensing.

[31]  R. Wolke,et al.  The Chemistry-Transport Modeling System lm-Muscat: Description and citydelta Applications , 2004 .

[32]  Robert M. Banta,et al.  Relationship between Low-Level Jet Properties and Turbulence Kinetic Energy in the Nocturnal Stable Boundary Layer , 2003 .

[33]  David Newman,et al.  Spatial heterogeneity in aeolian erodibility: Uniform, topographic, geomorphic, and hydrologic hypotheses , 2003 .

[34]  R. Washington,et al.  Dust-Storm Source Areas Determined by the Total Ozone Monitoring Spectrometer and Surface Observations , 2003 .

[35]  Robert G. Bryant,et al.  Ephemeral lakes and desert dust sources , 2003 .

[36]  J. Steppeler,et al.  Meso-gamma scale forecasts using the nonhydrostatic model LM , 2003 .

[37]  Ralf Wolke,et al.  The Parallel Model System LM-MUSCAT for Chemistry-Transport Simulations: Coupling Scheme, Parallelization and Applications , 2003, PARCO.

[38]  M. Heimann,et al.  Impact of vegetation and preferential source areas on global dust aerosol: Results from a model study , 2002 .

[39]  J. Schmetz,et al.  Supplement to An Introduction to Meteosat Second Generation (MSG): SEVIRI CALIBRATION , 2002 .

[40]  J. Schmetz,et al.  AN INTRODUCTION TO METEOSAT SECOND GENERATION (MSG) , 2002 .

[41]  Isabel F. Trigo,et al.  Climatology of Cyclogenesis Mechanisms in the Mediterranean , 2002 .

[42]  O. Torres,et al.  ENVIRONMENTAL CHARACTERIZATION OF GLOBAL SOURCES OF ATMOSPHERIC SOIL DUST IDENTIFIED WITH THE NIMBUS 7 TOTAL OZONE MAPPING SPECTROMETER (TOMS) ABSORBING AEROSOL PRODUCT , 2002 .

[43]  J. Lundquist,et al.  Nocturnal Low-Level Jet Characteristics Over Kansas During Cases-99 , 2002 .

[44]  N. Middleton,et al.  Saharan dust storms: nature and consequences , 2001 .

[45]  M. Chin,et al.  Sources and distributions of dust aerosols simulated with the GOCART model , 2001 .

[46]  Nick Middleton,et al.  Saharan dust: sources and trajectories , 2001 .

[47]  J. Slingo,et al.  The Diurnal Cycle in the Tropics , 2001 .

[48]  Sharon E. Nicholson,et al.  The nature of rainfall variability over Africa on time scales of decades to millenia , 2000 .

[49]  P. Davis,et al.  Development and mechanisms of the nocturnal jet , 2000 .

[50]  S. Doney,et al.  Iron supply and demand in the upper ocean , 2000 .

[51]  M. Legrand,et al.  Dust Variability over Northern Africa and Rainfall in the Sahel , 2000 .

[52]  Y. Balkanski,et al.  Modeling the mineralogy of atmospheric dust sources , 1999 .

[53]  I. Tegen,et al.  Radiative Forcing of a Tropical Direct Circulation by Soil Dust Aerosols , 1999 .

[54]  Larry Mahrt,et al.  Stratified Atmospheric Boundary Layers , 1999 .

[55]  P. Bhartia,et al.  Global distribution of UV-absorbing aerosols from Nimbus 7/TOMS data , 1997 .

[56]  C. Thorncroft,et al.  A Case Study of Saharan Cyclogenesis , 1997 .

[57]  Andrew A. Lacis,et al.  Modeling of particle size distribution and its influence on the radiative properties of mineral dust aerosol , 1996 .

[58]  Irina N. Sokolik,et al.  Direct radiative forcing by anthropogenic airborne mineral aerosols , 1996, Nature.

[59]  B. Marticorena,et al.  Modeling the atmospheric dust cycle: 1. Design of a soil-derived dust emission scheme , 1995 .

[60]  P. May.  The Australian nocturnal jet and diurnal variations of boundary‐layer winds over Mt. Isa in North‐eastern Australia , 1995 .

[61]  P. Alpert,et al.  Numerical experiments on the genesis of Sharav cyclones: idealized simulations , 1995 .

[62]  J. Garratt.  The Atmospheric Boundary Layer , 1992 .

[63]  G. Gutman,et al.  Dust Intrusion Events into the Mediterranean Basin. , 1991 .

[64]  C. Nappo.  Sporadic breakdowns of stability in the PBL over simple and complex terrain , 1991 .

[65]  Silas Michaelides,et al.  Atmospheric synoptic conditions associated with the initiation of north‐west African depressions , 1990 .

[66]  P. Alpert,et al.  Climatological analysis of Mediterranean cyclones using ECMWF data , 1990 .

[67]  P. Alpert,et al.  The Sharav Cyclone: Observations and some theoretical considerations , 1989 .

[68]  M. Tiedtke.  A Comprehensive Mass Flux Scheme for Cumulus Parameterization in Large-Scale Models , 1989 .

[69]  Roger K. Smith,et al.  On the Movement and Low-Level Structure of Cold Fronts , 1988 .

[70]  Toby N. Carlson,et al.  A case study of mobilization and transport of Saharan dust , 1988 .

[71]  G. Tetzlaff,et al.  The structure of West African Squall Lines and their environmental moisture budget , 1988 .

[72]  K. Droegemeier,et al.  Numerical Simulation of Thunderstorm Outflow Dynamics. Part I: Outflow Sensitivity Experiments and Turbulence Dynamics , 1987 .

[73]  N. Yamada.  A trial prediction of the values of some surface-layer turbulence constants using Schumann's method for promoting realizability , 1987 .

[74]  E. Schaller,et al.  A nocturnal low level jet during PUKK , 1985 .

[75]  K. Droegemeier.  The Numerical Simulation of Thunderstorm Outflow Dynamics , 1985 .

[76]  Donald H. Lenschow,et al.  The Rapid Morning Boundary-Layer Transition , 1979 .

[77]  A. Thorpe,et al.  The nocturnal jet , 1977 .

[78]  L. R. Hoxit.  Diurnal variations in planetary boundary-layer winds over land , 1975 .

[79]  Jess Charba,et al.  Application of Gravity Current Model to Analysis of Squall-Line Gust Front , 1974 .

[80]  S. B. Idso,et al.  An American Haboob , 1972 .

[81]  P. Lester,et al.  Richardson's number in the free atmosphere , 1968 .

[82]  J. Holton.  The diurnal boundary layer wind oscillation above sloping terrain , 1967 .

[83]  A. Blackadar.  Boundary Layer Wind Maxima and Their Significance for the Growth of Nocturnal Inversions , 1957 .