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Influence of the inter tropical discontinuity on Harmattan dust deposition in Ghana

Lyngsie, G. LU ; Olsen, J. L. LU ; Awadzi, T. W. ; Fensholt, R. and Breuning-Madsen, H. (2013) In Geochemistry, Geophysics, Geosystems 14(9). p.3425-3435
Abstract

The Harmattan is a dry dust-laden continental wind, and in the boreal winter Harmattan dust plumes affects many West African countries, including Ghana. When the Harmattan is strongest the southern part of Ghana is affected by the Inter Tropical Discontinuity (ITD). In this study, we investigate if the ITD functions as a barrier, preventing long transported Harmattan dust to settle south of, and below, it. This is done by analyzing a Harmattan dust outbreak, mapped using Earth observation (EO) data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) platform, coupled with data from West African AERONET stations, and comparing these observations with wind data from NOAA's Air... (More)

The Harmattan is a dry dust-laden continental wind, and in the boreal winter Harmattan dust plumes affects many West African countries, including Ghana. When the Harmattan is strongest the southern part of Ghana is affected by the Inter Tropical Discontinuity (ITD). In this study, we investigate if the ITD functions as a barrier, preventing long transported Harmattan dust to settle south of, and below, it. This is done by analyzing a Harmattan dust outbreak, mapped using Earth observation (EO) data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) platform, coupled with data from West African AERONET stations, and comparing these observations with wind data from NOAA's Air Resources Laboratory (ARL) program and the mineral suite of samples from seasonal dust deposits in north and south Ghana. In northern Ghana traces of minerals indicate a weak influence of particles from an arid environment, which is found consistent with the mapped dust plumes and NE wind directions. In southern Ghana the mineral composition show no sediments of an arid origin, the mapped dust plumes is less intense, and the surface wind directions and wind mass trajectories are more varying with lower wind speeds. Based on the results of this study it is concluded that dust deposited, or measured near ground, in the Harmattan period under the ITD, and south of it, does not contain material from the Chad Basin due to the local winds conditions.

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author
; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
keywords
aerosol optical depth, local and long transported mineral dust, West Africa
in
Geochemistry, Geophysics, Geosystems
volume
14
issue
9
pages
11 pages
publisher
American Geophysical Union (AGU)
external identifiers
  • scopus:84886685440
ISSN
1525-2027
DOI
10.1002/ggge.20212
language
English
LU publication?
no
id
564100b7-de44-48cf-b751-1a805307e131
date added to LUP
2016-10-17 14:09:16
date last changed
2022-04-11 12:20:11
@article{564100b7-de44-48cf-b751-1a805307e131,
  abstract     = {{<p>The Harmattan is a dry dust-laden continental wind, and in the boreal winter Harmattan dust plumes affects many West African countries, including Ghana. When the Harmattan is strongest the southern part of Ghana is affected by the Inter Tropical Discontinuity (ITD). In this study, we investigate if the ITD functions as a barrier, preventing long transported Harmattan dust to settle south of, and below, it. This is done by analyzing a Harmattan dust outbreak, mapped using Earth observation (EO) data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) platform, coupled with data from West African AERONET stations, and comparing these observations with wind data from NOAA's Air Resources Laboratory (ARL) program and the mineral suite of samples from seasonal dust deposits in north and south Ghana. In northern Ghana traces of minerals indicate a weak influence of particles from an arid environment, which is found consistent with the mapped dust plumes and NE wind directions. In southern Ghana the mineral composition show no sediments of an arid origin, the mapped dust plumes is less intense, and the surface wind directions and wind mass trajectories are more varying with lower wind speeds. Based on the results of this study it is concluded that dust deposited, or measured near ground, in the Harmattan period under the ITD, and south of it, does not contain material from the Chad Basin due to the local winds conditions.</p>}},
  author       = {{Lyngsie, G. and Olsen, J. L. and Awadzi, T. W. and Fensholt, R. and Breuning-Madsen, H.}},
  issn         = {{1525-2027}},
  keywords     = {{aerosol optical depth; local and long transported mineral dust; West Africa}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{9}},
  pages        = {{3425--3435}},
  publisher    = {{American Geophysical Union (AGU)}},
  series       = {{Geochemistry, Geophysics, Geosystems}},
  title        = {{Influence of the inter tropical discontinuity on Harmattan dust deposition in Ghana}},
  url          = {{http://dx.doi.org/10.1002/ggge.20212}},
  doi          = {{10.1002/ggge.20212}},
  volume       = {{14}},
  year         = {{2013}},
}