Preprints
https://doi.org/10.5194/acp-2021-932
https://doi.org/10.5194/acp-2021-932
 
23 Dec 2021
23 Dec 2021
Status: this preprint has been withdrawn by the authors.

Identifying Source Region Elemental Indicators in Aged Saharan Dust Plumes Over the Tropical Atlantic

Daniel E. Yeager1 and Vernon R. Morris1,2 Daniel E. Yeager and Vernon R. Morris
  • 1NOAA Center for Atmospheric Sciences, Howard University, Washington, D.C., United States
  • 2School of Mathematical and Natural Sciences, Arizona State University, Phoenix, AZ, United States

Abstract. This work examines the spatial dependency of Saharan dust aerosol composition over the Tropical Atlantic Ocean using observations collected during the 2015 Aerosols and Ocean Science Expedition (AEROSE). Regionally specific elemental indicators remain detectable in the dust samples collected along the Saharan air layer trajectory far into the Tropical Atlantic marine boundary layer. Saharan dust transport characteristics and elemental composition were determined by Inductively Coupled Plasma Mass Spectrometric (ICP-MS) analysis of airborne dust samples, ship-based radiometry, satellite aerosol retrievals, and atmospheric back-trajectory analysis. Three strong dust events (SDEs) and two trace dust events (TDEs) were detected during the campaign. The associated mineral dust arrived from potentially 7 different north African countries within 5 to 15 days of emission, according to transport analysis. Peak Na / Al and Ca / Al ratios (>1 and >1.5, respectively) in dust samples were traced to northern Saharan source regions in Western Sahara and Libya. In contrast, peak Fe / Al ratios (0.4–0.8) were traced to surface sources in southern Saharan regions in central Mauritania. We observe the highest ratios of (3–10) at sampling latitudes north of 15N in the Atlantic. Additionally, the sub-micron fraction of dust particulate settling over the Atlantic showed significant temporal and spatial variability, with coarse-fine Al ratios (at 0.8 microns) of 1.05, 0.65, and 0.95 for SDE1 (11/21–23), SDE2 (11/25–26), and SDE3 (11/28), respectively. This was consistent with elemental concentrations of Ca, Na, K, Ti, and Sr, per Al, that exhibited coarser size tendencies per dust event. These observations could validate spatially-sensitive aerosol models by predicting dust aerosol abundance and composition within the tropical Atlantic. Such predictions are critical towards understanding Saharan dust effects on regional climate, Atlantic Ocean biogeochemistry, satellite observations, and air quality modeling.

This preprint has been withdrawn.

Daniel E. Yeager and Vernon R. Morris

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-932', Anonymous Referee #1, 22 Apr 2022
  • RC2: 'Comment on acp-2021-932', Anonymous Referee #2, 01 May 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-932', Anonymous Referee #1, 22 Apr 2022
  • RC2: 'Comment on acp-2021-932', Anonymous Referee #2, 01 May 2022

Daniel E. Yeager and Vernon R. Morris

Daniel E. Yeager and Vernon R. Morris

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This preprint has been withdrawn.

Short summary
This work examines the spatial dependency of Saharan dust aerosol composition over the Tropical Atlantic Ocean using observations collected during the 2015 Aerosols and Ocean Science Expedition. We find that source region elemental signatures remain detectable in airborne dust samples collected far into the Tropical Atlantic Ocean. These observations could validate assessments of Saharan dust aerosol effects on regional climate, ocean ecosystems, satellite observations, and air quality.
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