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Discernible Rhythm in the Spatio/Temporal Distributions of Transatlantic Dust : Volume 11, Issue 8 (19/08/2011)

By Ben-ami, Y.

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Book Id: WPLBN0003993331
Format Type: PDF Article :
File Size: Pages 27
Reproduction Date: 2015

Title: Discernible Rhythm in the Spatio/Temporal Distributions of Transatlantic Dust : Volume 11, Issue 8 (19/08/2011)  
Author: Ben-ami, Y.
Volume: Vol. 11, Issue 8
Language: English
Subject: Science, Atmospheric, Chemistry
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Historic
Publication Date:
2011
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

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Kostinski, A. B., Lehahn, Y., Ben-Ami, Y., Altaratz, O., & Koren, I. (2011). Discernible Rhythm in the Spatio/Temporal Distributions of Transatlantic Dust : Volume 11, Issue 8 (19/08/2011). Retrieved from http://www.ebooklibrary.org/


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


Summary
Discernible rhythm in the spatio/temporal distributions of transatlantic dust

Excerpt
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, doi: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. doi: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, doi: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, doi:10.1029/2008JD011078, 2009.; Daubechies, I.: Ten lectures on wavelets, CBMS-NSF Lecture Notes nr. 61, SIAM, Philadelphia, 1992.; 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, doi:10.1029/2001GL013767, 2002.; Engelstaedter, S. and Washington, R.: Atmospheric controls on the annual cycle of North African dust, J. Geophys. Res., 112, D03103, doi: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, doi: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, doi: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, doi: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, doi: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, doi: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

 

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