• \
    Start Submission Become a Reviewer

    Reading: Dust mobilization and aerosol transport from West Africa to Cape Verde—a meteorological over...

    Download

     A- A+
    Alt. Display

    Original Research Papers

    Dust mobilization and aerosol transport from West Africa to Cape Verde—a meteorological overview of SAMUM-2

    Authors:

    Peter Knippertz ,

    School of Earth & Environment, University of Leeds, GB
    X close

    Matthias Tesche,

    Leibniz Institute for Tropospheric Research, DE
    X close

    Bernd Heinold,

    School of Earth & Environment, University of Leeds, GB
    X close

    Konrad Kandler,

    Institute for Applied Geosciences, Technical University Darmstadt, DE
    X close

    Carlos Toledano,

    Group of Atmospheric Optics, Valladolid University, ES
    X close

    Michael Esselborn

    European Southern Observatory, DE
    X close

    Abstract

    The second field campaign of the SAharan Mineral dUst experiMent (SAMUM-2) was performed between 15 January and 14 February 2008 at the airport of Praia, Cape Verde, and provided valuable information to study the westward transport of Saharan dust and the mixing with biomass-burning smoke and sea-salt aerosol. Here lidar, meteorological, and particle measurements at Praia, together with operational analyses, trajectories, and satellite and synoptic station data are used to give an overview of the meteorological conditions and to place other SAMUM-2 measurements into a large-scale context. It is demonstrated that wintertime dust conditions at Cape Verde are closely related to the movement and intensification of mid-latitude high-pressure systems and the associated pressure gradients at their southern flanks. These cause dust emission over Mauritania, Mali, and Niger, and subsequent westward transport to Cape Verde within about 1–5 d. Dust emissions often peak around midday, suggesting a relation to daytime mixing of momentum from nocturnal low-level jets to the surface. The dust layer over Cape Verde is usually restricted to the lowest 1.5 km of the atmosphere. During periods with near-surface wind speeds about 5.5 ms−1, a maritime aerosol layer develops which often mixes with dust from above. On most days, the middle levels up to about 5 km additionally contain smoke that can be traced back to sources in southernWest Africa. Above this layer, clean air masses are transported to Cape Verde with the westerly flow at the southern side of the subtropical jet. The penetration of extra-tropical disturbances to low latitudes can bring troposphere-deep westerly flow and unusually clean conditions to the region.

    How to Cite: Knippertz, P., Tesche, M., Heinold, B., Kandler, K., Toledano, C. and Esselborn, M., 2011. Dust mobilization and aerosol transport from West Africa to Cape Verde—a meteorological overview of SAMUM-2. Tellus B: Chemical and Physical Meteorology, 63(4), pp.430–447. DOI: http://doi.org/10.1111/j.1600-0889.2011.00544.x
      Published on 01 Jan 2011
    Peer Reviewed
     CC BY 4.0
     Accepted on 3 May 2011            Submitted on 26 Oct 2010

    References

    1. Ansmann , A. , Tesche , M. , Althausen , A. , Muller , D. , Freudenthaler , V. and co-authors . 2008 . Ice formation in Saharan dust over northern Africa observed during SAMUM. J. Geophys. Res . 113 , doi: https://doi.org/10.1029/2007JD008785 .  

    2. Ansmann , A. , Baars , H. , Tesche , M. , Muller , D. , Althausen , A. and co-authors . 2009a . Dust and smoke transport from Africa to South America: lidar profiling over Cape Verde and the Amazon rain forest. Geophys. Res. Lett . 36 , doi: https://doi.org/10.1029/2009GL037923 .  

    3. Ansmann , A. , Tesche , M. , Seifert , R , Althausen , A. , Engelmann , R. and co-authors . 2009b . Evolution of the ice phase in tropical altocumulus: SAMUM lidar observations over Cape Verde. J. Geophys. Res . 114 , doi: https://doi.org/10.1029/2008JD011659 .  

    4. Ansmann , A. , Petzold , A. , Kandler , K. , Tegen , I. , Wendisch , M. and co-authors . 2011 . Saharan Mineral Dust Experiments SAMUM-1 and SAMUM-2: what have we learned? Tellus 63B, this issue.  

    5. Bauer , S. E. , Mishchenlco , M. I. , Lacis , A. A. , Zhang , S. , Perlwitz , J. and co-authors . 2007 . Do sulfate and nitrate coatings on mineral dust have important effects on radiative properties and climate modeling? J. Geophys. Res . 112 , doi: https://doi.org/10.1029/2005JD006977 .  

    6. Barbosa , P.M. , Stroppiana , D. , Gregoire , J. M. and Pereira , J. M. C . 1999 . An assessment of vegetation fire in Africa (1981-1991): burned areas, burned biomass, and atmospheric emissions . Glob. Biogeochem. Cy-cles 13 , 933 – 950 .  

    7. Ben—Ami , Y. , Koren , I. and Altaratz , O . 2009 . Patterns of North African dust transport over the Atlantic: winter vs. summer, based on CALIPSO first year data . Atmos. Chem. Phys . 9 , 7867 – 7875 .  

    8. Ben—Ami , Y. , Koren , I. , Rudich , Y. , Artaxo , P. , Martin , S. T. and co-authors . 2010 . Transport of North African dust from the Bodele de-pression to the Amazon Basin: a case study. Atmos. Chem. Phys . 10 , 7533 - 7544 .  

    9. Carlson , T. N. and Caverly , R. S . 1977 . Radiative characteristics of Saharan dust at solar wavelengths . J. Geophys. Res . 82 , 3142 – 3152 .  

    10. Chiapello , I. , Bergametti , G. , Gomes , L. , Chaternet , B. , Dulac , F. , and co-authors . 1995 . An additional low layer transport of Sahelian and Saharan dust over the northeastern tropical Atlantic. Geophys. Res. Lett . 22 , 3191 - 3194 .  

    11. Chiapello , I. , Moulin , C. and Prospero , J. M . 2005 . Understanding the long-term variability of African dust transport across the Atlantic as recorded in both Barbados surface concentrations and large-scale Total Ozone Mapping Spectrometer (TOMS) optical thickness. J. Geophys. Res . 110 , doi: https://doi.org/10.1029/2004JDO05132 .  

    12. Cropp , R. A. , Gabric , A. J. , McTainsh , G. H. , Braddock , R. D. and Tindale , N . 2005 . Coupling between ocean biota and atmospheric aerosols: dust, dimethylsulphide, or artifact? Global Biogeochem. Cy-cles 19 , doi: https://doi.org/10.1029/2004GB002436 .  

    13. DeMott , P. J. , Sassen , K. , Poellot , M. R. , Baumgardner , D. , Rogers , D. C. and co-authors . 2003 . African dust aerosols as atmospheric ice nuclei. Geophys. Res. Lett . 30 , doi: https://doi.org/10.1029/2003GL017410 .  

    14. Engelmann , R. , Ansmann , A. , Tesche , M. , Seifert , P. , Althausen , A. and co-authors . 2011 . Doppler lidar studies of heat island effects on vertical mixing of aerosols during SAMUM-2. Tellus 63B, this issue.  

    15. Esselborn , M. , Wirth , M. , Fix , A. , Weinzierl , B. , Rasp , K. , and co-authors . 2009 . Spatial distribution and optical properties of Saharan dust observed by airborne high spectral resolution lidar during SA-MUM 2006. Tellus 61B , doi: https://doi.org/10.1111/j.1600-0889.2008.00394.x .  

    16. Evan , A. T. , Dunion , J. , Foley , J. A. , Heidinger , A. K. and Velden , C. S . 2006a . New evidence for a relationship between Atlantic tropical cyclone activity and African dust outbreaks. Geophys. Res. Lett . 33 , doi: https://doi.org/10.1029/2006GL026408 .  

    17. Evan , A. T. , Heidinger , A. K. and Knippertz , P . 2006b . Analysis of winter dust activity off the coast of West Africa using a new 24-year over water AVHRR satellite dust climatology. J. Geophys. Res . 111 , doi: https://doi.org/10.1029/2005JD006336 .  

    18. Freudenthaler , V , Esselborn , M. , Wiegner , M. , Heese , B. , Tesche , M. and co-authors . 2009 . Depolarization-ratio profiling at several wave-lengths in pure Saharan dust during SAMUM 2006. Tellus 61B , doi: j.1600-0889.2008.00396.x.  

    19. Ginoux , P. , Prospero , J. M. , Tones , O. and Chin , M . 2004 . Long-term simulation of global dust distribution with the GOCART model: cor-relation with North Atlantic Oscillation. Environ. Model. Software 19 , doi: https://doi.org/10.1016/S1364-8152(03)00114-2 .  

    20. Gong , S. L. , Barrie , L. A. and Blanchet , J. P . 1997 . Modeling sea—salt aerosols in the atmosphere 1. Model development . J. Geophys. Res . 102 , 3805 – 3818 .  

    21. Goudie , A. S. and Middleton , N. J . 2001 . Saharan dust storms: nature and consequences . Earth-Sci. Rev . 56 , 179 – 204 .  

    22. Groß , S. , Tesche , M. , Freudenthaler , V , Toledano , C. , Wiegner , M. , and co-authors . 2011a . Characterization of Saharan dust, marine aerosols, and a mixture of biomass burning aerosols and dust by means of multi-wavelength depolarization and Raman measurements during SAMUM-2. Tellus 63B, this issue.  

    23. Groß , S. , Freudenthaler , V , Wiegner , M ., Greifs , A. , Tesche , M. , and co-authors . 2011b . Characterization of the planetary boundary layer during SAMUM-2 by means of lidar measurements. Tellus 63B, this issue.  

    24. Haywood , J. , Francis , P. , Osborne , S. , Glew , M. , Loeb , N. and co-authors . 2003 . Radiative properties and direct radiative effect of Saharan dust measured by the C-130 aircraft during SHADE: 1. solar spectrum. J. Geophys. Res . 108 , doi: https://doi.org/10.1029/2002JD002687 .  

    25. Haywood J. M. , Pelon , J. , Formenti , P. , Bharmal , N. , Brooks , M. and co-authors . 2008 . Overview of the dust and biomass—burning experiment and African monsoon multidisciplinary analysis special observing period-O. J. Geophys. Res . 113 , doi: https://doi.org/10.1029/2008JD010077 .  

    26. Heinold , B. , Tegen , I. , Esselborn , M. , Kandler , K. , Knippertz , P. and co-authors . 2009 . Regional modeling of Saharan dust during the SAMUM 2006 campaign. Tellus 61B , doi:j.1600-0889.2008.00387.x.  

    27. Heinold , B. , Tegen , I. , Esselborn , M. , Kandler , K. , Knippertz , P. and co-authors . 2011 . Regional modeling of Saharan dust and biomass—burning. Part 1: model description and evaluation. Tellus 63B, this issue.  

    28. Heintzenberg , J . 2009 . The SAMUM-1 experiment over south-ern Morocco: overview and introduction. Tellus 61B , doi:j.1600-0889.2008.00403.x.  

    29. Huang , J. , Zhang , C. and Prospero , J. M . 2010 . African dust outbreaks: a satellite perspective of temporal and spatial variability over the tropi-cal Atlantic ocean. J. Geophys. Res . 115 , doi: https://doi.org/10.1029/2009JDO12516 .  

    30. Hultin , K. H. , Nilsson , E. D. , Krejci , R. , Mârtensson , E. M. , Ehn , M. and co-authors . 2010 . In situ laboratory sea spray production during the Marine Aerosol Production 2006 cruise on the northeastern Atlantic ocean. J. Geophys. Res . 115 , doi: https://doi.org/10.1029/2009JD012522 .  

    31. Johnson , T. B. , Osborne , S. R. , Haywood , J. M. and Harri-son , M. A. J . 2008 . Aircraft measurements of biomas-burning aerosol over West Africa during DABEX. J. Geophys. Res . 113 , doi: https://doi.org/10.1029/2007JD009451 .  

    32. Kalu , A. E . 1979 . The African dust plume: its characteristics and prop-agation across West Africa in winter. In Saharan Dust . (ed. Morales , C. ). J. Wiley and Sons, Chichester, 95 - 118 .  

    33. Kandler , K. , Schiitz , L. , Jäckel , S. , Lieke , K. , Emmel , C. and co-authors . 2011 . Ground-based of—line aerosol measurements at Praia, Cape Verde, during the Saharan Mineral Dust Experiment: microphysical properties and mineralogy. Tellus 63B, this issue.  

    34. Kaufmann , Y. J. , Koren , I. , Remer , L. A. , Tanre , D. , Ginoux , P. , and co-authors . 2005 . Dust transport and deposition observed from the Terra—Moderate Resolution Imaging Spectroradiometer (MOD'S) spacecraft over the Atlantic ocean. J. Geophys. Res . 110 , doi: https://doi.org/10.1029/2003JD004436 .  

    35. Knippertz , P. and Fink , A. H . 2006 . Synoptic and dynamic aspects of an extreme springtime Saharan dust outbreak . Quart. J. Roy. MeteoroL Soc . 132 , 1153 – 1177 .  

    36. Knippertz , P . 2008 . Dust mobilization in the West African heat trough—the role of the diurnal cycle and of extratropical synoptic disturbances . Meteorol. Zeitschr 17 , 553 – 563 .  

    37. Knippertz , P. , Ansmann , A. , Althausen , D. , Muller , D. , Tesche , M. and co-authors . 2009 . Dust mobilization and transport in the northern Sahara during SAMUM 2006—a meteorological overview. Tellus 61B , doi: https://doi.org/10.1111/j.1600-0889.2008.00380.x .  

    38. Li , J. , Zhang , T. , Schmit , J. , Schmetz , J. and Menzel , W . 2007 . Technical note: quantitative monitoring of a Saharan dust event with SEVIRI on Meteosat-8 . Int. J. Remote Sens . 28 , 2181 – 2186 .  

    39. Lieke , K. , Kandler , K. , Schiitz , L. , Petzold , A. , Weinzierl , B. , and co-authors . 2011 . Particle chemical properties in the vertical column based on aircraft observations in the vicinity of Cape Verde islands. Tellus 63B, this issue.  

    40. Liu , Z. , Omar , A. , Vaughan , M. , Hair , J. , Kittalca , C. and co-authors . 2008 . CALIPSO lidar observations of the optical properties of Saharan dust: a case study of long—range transport. J. Geophys. Res . 113 , doi: https://doi.org/10.1029/2007JD008878 .  

    41. Mahowald , N. M. , Luo , C. , del Corral , J. and Zender , C. S . 2003 . Interannual variability in atmospheric mineral aerosols from a 22-year model simulation and observational data. J. Geophys. Res . 108 , doi: https://doi.org/10.1029/2002JD002821 .  

    42. Mahowald , N. M. , Baker , A. R. , Bergametti , G. , Brooks , N. , Duce , R. A. and co-authors . 2005 . Atmospheric global dust cy-cle and iron inputs to the ocean. Global Biogeochem. Cycles 19 , doi: https://doi.org/10.1029/2004GB002402 .  

    43. Monahan , E. C. , Fairall , C. W. , Davidson , K. L. and Boyle , P. J . 1983 . Observed interrelations between 10—m winds, ocean white-caps, and marine aerosols . Quart. J. Roy. Meteor Soc . 109 , 379 – 392 .  

    44. Moulin , C. , Lambert , C. E. , Dulac , F. and Dayan , U . 1997 . Control of atmospheric export of dust from North Africa by the North Atlantic Oscillation . Nature 387 , 691 – 694 .  

    45. Martensson , E. M. , Nilsson , E. D. , de Leeuw , G. , Cohen , L. H. and Hansson , H. C . 2003 . Laboratory simulations and parameterization of the primary marine aerosol production. J. Geophys. Res . 108 , doi: https://doi.org/10.1029/2002JD002263 .  

    46. McKendry , I. G. , Strawbridge , K. B. , O'Neill , N. T. , Macdonald , A. M. , Liu , P. S. K. and co-authors . 2007 . Trans—Pacific transport of Saharan dust to western North America: a case study. J. Geophys. Res . 112 , doi: https://doi.org/10.1029/2006JD007129 .  

    47. Möhler , O. , Benz , S. , Saathoff , H. , Schnaiter , M. , Wagner , R. , and coau-thors 2008. The effect of organic coating on the heterogeneous ice nucleation efficiency of mineral dust aerosols. Environ. Res. Lett . 3 , doi: https://doi.org/10.1088/1748-9326/3/2/025007 .  

    48. Morales , C . 1986 . The airborne transport of Saharan dust: a review . Clim. Change 9 , 219 – 241 .  

    49. Muller , T. , Schladitz , A. and Wiedensohler , A . 2011 . Spectral par-ticle absorption coefficients, single scattering albedos, and imagi-nary parts of refractive indices from ground based in-situ measure-ments at Cape Verde Island during SAMUM-2. Tellus 63B, this issue.  

    50. Pelon , J. , Mallet , M. , Mariscal , A. , Goloub , R , Tanfe , D. and co-authors . 2008 . Microlidar observations of biomass-burning aerosol over Djougou (Benin) during African monsoon multidisciplinary analysis special observation period 0: dust and biomass-burning ex-periment. J. Geophys. Res . 113 , doi: https://doi.org/10.1029/2008JD009976 .  

    51. Petzold , A. , Veira , A. , Mund , S. , Esselborn , M. , Kiemle , C. and co-authors . 2011 . Mixing of mineral dust with ur-ban pollution aerosol over Dakar (Senegal)—impact on dust physico—chemical and radiative properties. Tellus 63B, this issue.  

    52. Prospero , J. M. and Carlson , T. N . 1972 . Vertical and areal distribution of Saharan dust over the western equatorial North Atlantic ocean . J. Geophys. Res . 77 , 5255 – 5265 .  

    53. Prospero , J. M. and Carlson , T. N . 1980 . Saharan air outbreaks over the tropical North Atlantic . Pure AppL Geophys . 119 , 677 – 691 .  

    54. Rosenfeld , D. , Rudich , Y. and Lahav , R . 2001 . Desert dust suppress-ing precipitation: a possible desertification feedback loop. PNAS 98 , doi: https://doi.org/10.1073/pnas.101122798 .  

    55. Sassen , K. and Weitkamp , C. eds. 2005 . Polarization in Lidar. LIDAR—Range-Resolved Optical Remote Sensing of the Atmosphere, Springer Series in Optical Sciences . Springer, New York, 19 - 42 .  

    56. Schepanslci , K. , Tegen , I. , Laurent , B. , Heinold , B. and Macke , A . 2007 . A new Saharan dust source activation frequency map de-rived from MSG-SEVIRI IR-channels. Geophys. Res. Lett . 34 , doi: https://doi.org/10.1029/2007GL030168 .  

    57. Schepanslci , K. , Tegen , I. , Todd , M. C. , Heinold , B. , Biinisch , G. , and co-authors . 2009 . Meteorological processes forcing Saharan dust emission inferred from MSG-SEVIRI observations of subdaily dust source activation and numerical models. J. Geophys. Res . 114 , doi: https://doi.org/10.1029/2008JD010325 .  

    58. Schladitz , A. , Muller , T. , Nowak , A. , Kandler , K. , Lieke , K. , and co-authors . 2011 . In-situ aerosol characterization at Cape Verde. Part 1: particle number size distributions, hygroscopic growth and state of mixing of the marine and Saharan dust aerosol. Tellus 63B, this issue.  

    59. Slingo , A. , Ackermann , T. P. , Allan , R. P. , Kassianov , E. I. , McFarlane , S. A. and co-authors . 2006 . Observations of the impact of a major Saharan dust storm on the atmospheric radiation balance. Geophys. Res. Lett . 33 , doi: https://doi.org/10.1029/2006GL027869 .  

    60. Sokolilc , I. , Toon , O. and Bergstrom , R . 1998 . Modeling the radiative characteristics of airborne mineral aerosols at infrared wavelengths . J. Geophys. Res . 103 , 8813 – 8826 .  

    61. Swap , R. , Garstang , M. , Greco , S. , Talbot , R. and Milberg , P . 1992 . Saharan dust in the Amazon basin . Tellus 44B , 133 – 149 .  

    62. Tanre , D. , Haywood , J. , Pelon , J. , Leon , J. F. , Chatenet , B. and co-authors . 2003 . Measurement and modeling of the Saharan dust radia-tive impact: overview of the Saharan Dust Experiment (SHADE). J. Geophys. Res . 108 , doi: https://doi.org/10.1029/2002JD003273 .  

    63. Tesche , M. , Ansmann , A. , Muller , D. , Althausen , D. , Mattis , I. and co-authors . 2009a . Vertical profiling of Saharan dust with Raman lidars and airborne HSRL in southern Morocco during SAMUM. Tellus 61B , doi:j.1600-0889.2008.00390.x.  

    64. Tesche , M. , Ansmann , A. , Muller , D. , Althausen , D. , Engelmann , R. , and co-authors . 2009b . Vertically resolved separation of dust and smoke over Cape Verde by using multiwavelength Raman and polarization lidars during Saharan Mineral Dust Experiment 2008. J. Geophys. Res . 114 , doi: https://doi.org/10.1029/2009JD011862 .  

    65. Tesche , M ., Grofs , S. , Ansmann , A. , Muller , D. , Althausen , D. and co-authors . 2011a . Profiling of Saharan dust and biomass—burning smoke with multiwavelength polarization Raman lidar at Cape Verde. Tellus 63B, this issue.  

    66. Tesche , M. , Muller , D ., Grofs , S. , Ansmann , A. , Althausen , D. and co-authors . 2011b . Optical and microphysical properties of smoke over Cape Verde as inferred from lidar measurements. Tellus 63B, this issue.  

    67. Todd , M. C. , Bou Karam , D. , Cavazos , C. , Bouet , C. , Heinold , B. and co-authors . 2008 . Quantifying uncertainty in estimates of mineral dust flux: an intercomparison of model performance over the Bodele Depression, northern Chad. J. Geophys. Res . 113 , doi: https://doi.org/10.1029/2008JDO10476 .  

    68. Toledano , C. , Wiegner , M. , Garhammer , M. , Seefeldner , M. , Garsteiger , J. , and co-authors . 2011 . Optical properties of aerosol mixtures de-rived from sun—sky radiometry during SAMUM-2. Tellus 63B, this issue.  

    69. Wernli , H. and Davies , H. C . 1997 . A Lagrangian—based analysis of extratropical cyclones. I: the method and some applications . Quart. J. Roy. Meteor Soc . 123 , 467 – 489 .  

    70. Washington , R. and Todd , M. C . 2005 . Synoptic and dynamic aspects of an extreme springtime Saharan dust outbreak. Geophys. Res. Lett . 32 , doi: https://doi.org/10.1029/2005GL023597 .  

    71. Wu , L . 2007 . Impact of Saharan air layer on hurricane peak intensity. Geophys. Res. Lett . 34 , doi: https://doi.org/10.1029/2007GL029564 .  

    72. Wurzler , S. , Reisin , T. G. and Levin , Z . 2000 . Modification of mineral dust particles by cloud processing and subsequent ef-fects on drop size distributions . J. Geophys. Res . 105 , 4501 – 4512 .  

    Jump to Discussions Related content
    comments powered by Disqus