References

ACPD

Atmospheric Chemistry and Physics Discussions

ACPD

1680-7375

Copernicus GmbH

Göttingen, Germany

10.5194/acpd-11-23513-2011

Discernible rhythm in the spatio/temporal distributions of transatlantic dust

Ben-Ami

¹ Koren

¹ Altaratz

¹ Kostinski

A. B.

² Lehahn

¹ ³

Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot, Israel

Department of Physics, Michigan Technological University, Houghton, Michigan, USA

Department of Geophysics and Planetary Sciences, Tel Aviv University, Tel Aviv, Israel

19 08 2011

11 8 23513 23539

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The differences in North African dust emission regions and transport routes, between the boreal winter and summer are thoroughly documented. Here we re-examine the spatial and temporal characteristics of dust transport over the tropical and subtropical North Atlantic Ocean, using 10 years of satellite data, in order to determine better the different dust transport periods and their characteristics. We see a robust annual triplet: a discernible rhythm of "transatlantic dust weather". The proposed annual partition is composed of two heavy loading periods, associated here with a northern-route period and southern-route period, and one clean, light-loading period, accompanied by unusually low average optical depth of dust. The two dusty periods are quite different in character: their duration, transport routes, characteristic aerosol loading and frequency of pronounced dust episodes. The southern route period lasts about ~4 months, from the end of November to end of March. It is characterized by a relatively steady southern positioning, low frequency of dust events, low background values and high variance in dust loading. The northern-route period lasts ~6.5 months, from the end of March to mid October, and is associated with a steady drift northward of ~0.1 latitude day−1, reaching ~1500 km north of the southern route. The northern period is characterized by higher frequency of dust events, higher (and variable) background and smaller variance in dust loading. It is less episodic than the southern period. Transitions between the periods are brief. Separation between the southern and northern periods is marked by northward latitudinal shift in dust transport and by moderate reduction in the overall dust loading. The second transition between the northern and southern periods commences with an abrupt reduction in dust loading (thereby initiating the clean period) and rapid shift southward of ~0.2 latitude day−1, and 1300 km in total. These rates of northward advance and southern retreat of the dust transport route are in accordance with the simultaneous shift of the Inter Tropical Front. Based on cross-correlation analyses, we attribute the observed rhythm to the contrast between the northwestern and southern Saharan dust source spatial distributions. Despite the vast difference in areas, the Bodélé Depression, located in Chad, appears to modulate transatlantic dust patterns about half the time. The proposed partition captures the essence of transatlantic dust climatology and may, therefore, supply a natural temporal framework for dust analysis via models and observations.

References 1

Ben-Ami, Y., Koren, I., Rudich, Y., Artaxo, P., Martin, S. T., and Andreae, M. O.: Transport of North African dust from the Bodérlé depression to the Amazon Basin: a case study, Atmos. Chem. Phys., 10, 7533–7544, http://dx.doi.org/10.5194/acp-10-7533-2010doi:10.5194/acp-10-7533-2010, 2010.

Bou Karam, D., Flamant, C., Knippertz, P., Reitebuch, O., Pelon, J., Chong, M., and Dabas, A.: Dust emissions over the Sahel associated with the West African monsoon intertropical discontinuity region: A representative case-study, Q. J. Roy. Meteor. Soc., 134, 621–634. http://dx.doi.org/10.1002/qj.244doi:10.1002/qj.244, 2008.

Bou Karam, D., Flamant, C., Cuesta, J., Pelon, J., and Williams, E.: Dust emission and transport associated with a Saharan depression: The February 2007 case, J. Geophys. Res., 115, D00H27, http://dx.doi.org/10.1029/2009JD012390doi:10.1029/2009JD012390, 2010.

Cavazos, C., Todd, M. C., and Schepanski, K.: Numerical model simulation of the Saharan dust event of 6–11~March~2006 using the Regional Climate Model version 3 (RegCM3), J. Geophys. Res. Atmos., 114, D12109, http://dx.doi.org/10.1029/2008JD011078doi:10.1029/2008JD011078, 2009.

Chiapello, I. and Moulin, C.: TOMS and METEOSAT satellite records of the variability of Saharan dust transport over the Atlantic during the last two decades (1979–1997), J. Geophys. Res. Lett., 29, 17–20, http://dx.doi.org/10.1029/2001GL013767doi:10.1029/2001GL013767, 2002.

Daubechies, I.: Ten lectures on wavelets, CBMS-NSF Lecture Notes nr. 61, SIAM, Philadelphia, 1992.

Engelstaedter, S. and Washington, R.: Atmospheric controls on the annual cycle of North African dust, J. Geophys. Res., 112, D03103, http://dx.doi.org/10.1029/2006jd007195doi:10.1029/2006jd007195, 2007.

Engelstaedter, S., Washington, R., and Tegen, I.: North African dust emissions and transport, Earth-Sci. Rev., 79, 73–100, 2006.

Engelstaedter, S., Washington, R., and Mahowald, N.: Impact of changes in atmospheric conditions in modulating summer dust concentration at Barbados: A back-trajectory analysis, J. Geophys. Res., 114, D17111, http://dx.doi.org/10.1029/2008JD011180doi:10.1029/2008JD011180, 2009.

Formenti, P., Rajot, J. L., Desboeufs, K., Caquineau, S., Chevaillier, S., Nava, S., Gaudichet, A., Journet, E., Triquet, S., Alfaro, S., Chiari, M., Haywood, J., Coe, H., Highwood, E.: Regional variability of the composition of mineral dust from western Africa: Results from the AMMA SOP0/DABEX and DODO field campaigns, J. Geophys. Res., 113, D00C13, http://dx.doi.org/10.1029/2008JD009903doi:10.1029/2008JD009903, 2008.

Formenti, P., Schuetz, L., Balkanski, Y., Desboeufs, K., Ebert, M., Kandler, K., Petzold, A., Scheuvens, D., Weinbruch, S., and Zhang, D.: Recent progress in understanding physical and chemical properties of mineral dust, Atmos. Chem. Phys. Discuss., 10, 31187–31251, http://dx.doi.org/10.5194/acpd-10-31187-2010doi:10.5194/acpd-10-31187-2010, 2010

Ginoux, P., Prospero, J. M., Torres, O., and Chin, M.: Long-term simulation of global dust distribution with the GOCART model: correlation with North Atlantic Oscillation, Environment. Modell. Softw., 19, 113–128, http://dx.doi.org/10.1016/S1364-8152(03)00114-2doi:10.1016/S1364-8152(03)00114-2, 2004.

Griffin, D. W. and Kellogg, C. A.: Dust storms and their impact on ocean and human health: dust in Earth's atmosphere, Ecohealth, 1, 248–295, http://dx.doi.org/10.1007/s10393-004-0120-8doi:10.1007/s10393-004-0120-8, 2004.

Haywood, J., Francis, P., Osborne, S., Glew, M., Loeb, N., Highwood, E., Tanré, D., Myhre, G., Formenti, P., and Hirst, E.: Radiative properties and direct radiative effect of Saharan dust measured by the C-130 aircraft during SHADE: 1. Solar spectrum, J. Geophys. Res., 108(16), 8577, http://dx.doi.org/10.1029/2002JD002687doi:10.1029/2002JD002687, 2003.

Highwood, E. J., Haywood, J. M., Silverstone, M. D., Newman, S. M., and Taylor, J. P.: Radiative properties and direct effect of Saharan dust measured by the C-130 aircraft during Saharan Dust Experiment (SHADE): 2. Terrestrial spectrum, J. Geophys. Res., 108(13), 8578, http://dx.doi.org/10.1029/2002JD002552doi:10.1029/2002JD002552, 2003.

Hsu, N. C., Tsay, S. C., King, M. D., and Herman, J. R.: Aerosol properties over bright-reflecting source regions, IEEE T. Geosci. Remote, 42, 557–569, 2004.

Huang, J., Zhang, C., and Prospero, J. M.: African dust outbreaks: A satellite perspective of temporal and spatial variability over the tropical Atlantic Ocean, J. Geophys. Res., 115, D05202, http://dx.doi.org/10.1029/2009JD012516doi:10.1029/2009JD012516, 2010.

Huneeus, N., Schulz, M., Balkanski, Y., Griesfeller, J., Prospero, J., Kinne, S., Bauer, S., Boucher, O., Chin, M., Dentener, F., Diehl, T., Easter, R., Fillmore, D., Ghan, S., Ginoux, P., Grini, A., Horowitz, L., Koch, D., Krol, M. C., Landing, W., Liu, X., Mahowald, N., Miller, R., Morcrette, J.-J., Myhre, G., Penner, J., Perlwitz, J., Stier, P., Takemura, T., and Zender, C. S.: Global dust model intercomparison in AeroCom phase I, Atmos. Chem. Phys., 11, 7781–7816, http://dx.doi.org/10.5194/acp-11-7781-2011doi:10.5194/acp-11-7781-2011, 2011.

Janicot, S., Thorncroft, C. D., Ali, A., Asencio, N., Berry, G., Bock, O., Bourles, B., Caniaux, G., Chauvin, F., Deme, A., Kergoat, L., Lafore, J.-P., Lavaysse, C., Lebel, T., Marticorena, B., Mounier, F., Nedelec, P., Redelsperger, J.-L., Ravegnani, F., Reeves, C. E., Roca, R., de Rosnay, P., Schlager, H., Sultan, B., Tomasini, M., Ulanovsky, A., and ACMAD forecasters team: Large-scale overview of the summer monsoon over West Africa during the AMMA field experiment in 2006, Ann. Geophys., 26, 2569–2595, http://dx.doi.org/10.5194/angeo-26-2569-2008doi:10.5194/angeo-26-2569-2008, 2008.

Jickells, T. D., An, Z. S., Andersen, K. K., Baker, A. R., Bergametti, G., Brooks, N., Cao, J. J., Boyd, P. W., Duce, R. A.,. Hunter, K. A, Kawahata, H., Kubilay, N., laRoche, J., Liss, P. S., Mahowald, N., Prospero, J. M., Ridgwell, A. J., Tegen, I., and Torres, R.: Global Iron Connections Between Desert Dust, Ocean Biogeochemistry and Climate, Science, 308, 67–71, http://dx.doi.org/10.1126/science.1105959doi:10.1126/science.1105959, 2005.

Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Leetmaa, A., Reynolds, R., Chelliah, M., Ebisuzaki,W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C.,Wang, J., Jenne, R., and Joseph, D.: The NCEP/NCAR 40-Year Reanalysis Project, B. Am. Meteorol. Soc., 3, 43–471, 1996.

Kalu, A. E., The African dust plume: Its characteristics and propagation across West Africa in winter, in Saharan Dust: Mobilization, Transport, and Deposition, SCOPE 14, edited by C. Morales, 95–118, John Wiley, New York, USA, 1979.

Karyampudi, V. M. and Carlson, N. T.: Analysis and numerical simulations of the Saharan Air Layer and its effect on easterly wave disturbances, J. Atmos. Sci., 45, 3102–3136, 1988.

Karyampudi, V. M., Palm, S. P., Reagen, J. A., Fang, H., Grant, W. B., Hoff, R. M., Moulin, C., Pierce, H. F., Torres, O., Browell, E. V., and Melfi, S. H.: Validation of the Saharan dust plume conceptual model using lidar, Meteosat and ECMWF, B. Am. Meteorol. Soc., 80, 1045–1075, 1999.

Kaufman, Y. J., Koren, I., Remer, L. A., Tanre, D., Ginoux, P., and Fan, S.: Dust transport and deposition observed from the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean, J. Geophys. Res., 110, D10S12, http://dx.doi.org/10.1029/2003JD004436doi:10.1029/2003JD004436, 2005a.

Kaufman, Y. J., Remer, L. A., Tanre, D., Li, R. R., Kleidman, R., Mattoo, S., Levy, R., Eck, T., Holben, B. N., Ichoku, C., Martins, J., and Koren, I.: A critical examination of the residual cloud contamination and diurnal sampling effects on MODIS estimates of aerosol over ocean, IEEE T. Geosci. Remote, 43, 2886–2897, 2005b.

Kim, K. W., Kim, Y. J., and Oh, S. J.: Visibility impairment during Yellow Sand periods in the urban atmosphere of Kwangju, Korea, Atmos. Environ., 35(30), 5157–5167, http://dx.doi.org/10.1016/S1352-2310(01)00330-2doi:10.1016/S1352-2310(01)00330-2, 2001.

Knippertz, P. and Fink, A. H.: Synoptic and Dynamic Aspects of an Extreme Springtime Saharan Dust Outbreak, Q. J. Roy. Meteor. Soc., 132, 1153–1177, http://dx.doi.org/10.1256/qj.05.109doi:10.1256/qj.05.109, 2006.

Koren, I. and Kaufman, Y. J.: Direct wind measurements of Saharan dust events from Terra and Aqua satellites, J. Geophys. Res. Lett., 31, L06122, http://dx.doi.org/10.1029/2006GL026024doi:10.1029/2006GL026024, 2004.

Koren, I., Kaufman, Y. J., Washington, R., Todd, C. C., Rudich, Y., Martins, J. V., and Rosenfeld, D.: The Bodélé depression: a single spot in the Sahara that provides most of the mineral dust to the Amazon forest, Environ. Res. Lett., 1, 1–5, 2006.

Lavaysse, C., Flamant, C., Janicot, S., Parker, D. J., Lafore, J. P., Sultan, B., and Pelon, J.: Seasonal evolution of the West African heat low: A climatological perspective, Clim. Dynam., 33, 313–330, http://dx.doi.org/10.1007/s00382-009-0553-4doi:10.1007/s00382-009-0553-4, 2009.

Lélé, M. I. and Lamb, P. J.: Variability of the Intertropical Front (ITF) and rainfall over the West African Sudan–Sahel zone, J. Climate, 23, 3984–4004, doi:2010/10.1175JCLI3277.1, 2010.

Ozer, P., Laghdaf, M., Lemine, S. O. M., and Gassani, J.: Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal visibility data, Water Air Soil Poll., 178, 79–87, 2007.

Prenni, A. J., Petters, M. D., Kreidenweis, S. M., Heald, C. L., Martin, S. T., Artaxo, P., Garland, R. M., Wollny, A. G., and P\"o oschl, U.: Relative roles of biogenic emissions and Saharan dust as ice nuclei in the Amazon Basin, Nat. Geosci., 2, 402–405, 2009.

Prospero, J. M.: The atmospheric transport of particles to the ocean, in Ittekkot V, Schäfer P, Honjo S, and Depetris P J (eds) Particle Flux in the Ocean SCOPE Report 57 John Wiley & Sons Chichester 19–52, 1996.

Prospero, J. M.: Long-term measurements of the transport of African mineral dust to the southeastern United States: Implications for regional air quality, J. Geophys. Res., 104, 15917–15927, 1999.

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

Prospero, J. M. and Nees, R. T.: Dust concentration in the atmosphere of the equatorial North Atlantic: Possible relationship to the Sahelian drought, Science, 196, 1196–1198, 1977.

Reid, J. S., Westphal, D., LLivingston, J. M., Savoie, D. L., Maring, H. B., Jonsson, H. H., Eleuterio, D. P., Kinney, J. E., and Reid, E. A.: Dust vertical distribution in the Caribbean during the Puerto Rico Dust Experiment, J. Geophys. Res., 29, 1151, doi.:10.1029/2001GL014092, 2002.

Reid, J. S., Kinney, J. E., Westphal, D. L., Holben, B. N., Welton, E. J., Tsay, S., Eleuterio, D. P., Campbell, J. R., Christopher, S. A., Colarco, P. R., Jonsson, H. H., Livingston, J. M., Maring, H. B., Meier, M. L., Pilewskie, P., Prospero, J. M., Reid, E. A., Remer, L. A., Russell, P. B., Savoie, D. L., Smirnov, A., and Tanré , D.: Analysis of measurements of Saharan dust by airborne and ground-based remote sensing methods during the Puerto Rico Dust Experiment (PRIDE), J. Geophys. Res., 108, D19,8586, http://dx.doi.org/10.1029/2002JD002493doi:10.1029/2002JD002493, 2003.

Remer, L. A., Kleidman, R. G., Levy, R. C., Kaufman, Y. J., Tanre, D., Mattoo, S., Martins, J. V., Ichoku, C., Koren, I., Yu, H. B., and Holben, B. N.: Global aerosol climatology from the MODIS satellite sensors, J. Geophys. Res., 113, D14S07, http://dx.doi.org/10.1029/2007JD009661doi:10.1029/2007JD009661, 2008.

Schepanski, K., Tegen, I., and Macke, A.: Saharan dust transport and deposition towards the tropical northern Atlantic, Atmos. Chem. Phys., 9, 1173–1189, http://dx.doi.org/10.5194/acp-9-1173-2009doi:10.5194/acp-9-1173-2009, 2009.

Slingo, A., Ackerman, T. P., Allan, R. P., Kassianov, E. I., McFarlane, S. A., Robinson, G. J., Barnard, J. C., Miller, M. A., Harries, J. E., Russell, J. E., and Dewitte, S.: Observations of the impact of a major Saharan dust storm on the atmospheric radiation balance, J. Geophys. Res., 33, L24817, http://dx.doi.org/10.1029/2006GL027869doi:10.1029/2006GL027869, 2006.

Sundar, A. C. and Thomas, A. J.: Satellite and surface-based remote sensing of Saharan dust aerosols, Remote Sens. Environ., 114, 1002–1007, 2010.

Thomas, M. and Gautier, C.: Investigations of the March 2006 African dust storm using ground-based column-integrated high spectral resolution infrared (8–13 μm) and visible aerosol optical thickness measurements: 2 Mineral aerosol mixture analyses, J. Geophys. Res., 114, D14209, http://dx.doi.org/10.1029/2008JD010931doi:10.1029/2008JD010931, 2009.

Torres, O., Bhartia, P. K., Herman, J. R., Sinyuk, A., Ginoux, P., and Holben, B.: A long-term record of aerosol optical depth from TOMS observations and comparison to AERONET measurements, J. Atmos. Sci., 59, 398–413, 2002.

Tulet, P., Mallet, M., Pont, V., Pelon, J., and Boone A.: The 7–13 March 2006 dust storm over West Africa: Generation, transport, and vertical stratification, J. Geophys. Res., 113(13), D00C08, http://dx.doi.org/10.1029/2008JD009871doi:10.1029/2008JD009871, 2008.

Usher, C. R., Michel, A. E., and Grassian, V. H.: Reactions on mineral dust, Chem. Rev., 103, 4883–4939, 2003.

Washington, R. and Todd, M.C.: Atmospheric controls on mineral dust emission from the Bodélé Depression, Chad: The role of the low level jet, J. Geophys. Res., 32, L17701, http://dx.doi.org/10.1029/2005GL023597doi:10.1029/2005GL023597, 2005.

Yu, H. B., Chin, M., Remer, L. A., Kleidman, R. G., Bellouin, N., Bian, H. S., and Diehl, T.: Variability of marine aerosol fine mode fraction and estimates of anthropogenic aerosol component over cloud-free oceans from the Moderate Resolution Imaging Spectroradiometer (MODIS), J. Geophys. Res., Atmosphere, 114, D10206, http://dx.doi.org/10.1029/2008JD010648doi:10.1029/2008JD010648, 2009.