The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky

Paquita Zuidema, Arthur J. Sedlacek, Connor Flynn, Stephen Springston, Rodrigo Delgadillo, Jianhao Zhang, Allison C. Aiken, Annette Koontz, Paytsar Muradyan

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Observations from June to October 2016, from a surface-based ARM Mobile Facility deployment on Ascension Island (8°S, 14.5°W) indicate that refractory black carbon (rBC) is almost always present within the boundary layer. The rBC mass concentrations, light absorption coefficients, and cloud condensation nuclei concentrations vary in concert and synoptically, peaking in August. Light absorption coefficients at three visible wavelengths as a function of rBC mass are approximately double that calculated from black carbon in lab studies. A spectrally-flat absorption angstrom exponent suggests most of the light absorption is from lens-coated black carbon. The single-scattering-albedo increases systematically from August to October in both 2016 and 2017, with monthly means of 0.78 ± 0.02 (August), 0.81 ± 0.03 (September), and 0.83 ± 0.03 (October) at the green wavelength. Boundary layer aerosol loadings are only loosely correlated with total aerosol optical depth, with smoke more likely to be present in the boundary layer earlier in the biomass burning season, evolving to smoke predominantly present above the cloud layers in September-October, typically resting upon the cloud top inversion. The time period with the campaign-maximum near-surface light absorption and column aerosol optical depth, on 13-16 August 2016, is investigated further. Backtrajectories that indicate more direct boundary layer transport westward from the African continent is central to explaining the elevated surface aerosol loadings.

Original languageEnglish (US)
JournalGeophysical Research Letters
DOIs
StateAccepted/In press - Jan 1 2018

Fingerprint

black carbon
boundary layers
electromagnetic absorption
boundary layer
aerosols
refractories
carbon
aerosol
smoke
absorption coefficient
optical thickness
optical depth
absorptivity
wavelength
condensation nuclei
biomass burning
cloud condensation nucleus
continents
albedo
wavelengths

Keywords

  • Absorbing aerosol
  • DOE AMF1
  • Remote southeast Atlantic
  • Smoke

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

Zuidema, P., Sedlacek, A. J., Flynn, C., Springston, S., Delgadillo, R., Zhang, J., ... Muradyan, P. (Accepted/In press). The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky. Geophysical Research Letters. https://doi.org/10.1002/2017GL076926

The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky. / Zuidema, Paquita; Sedlacek, Arthur J.; Flynn, Connor; Springston, Stephen; Delgadillo, Rodrigo; Zhang, Jianhao; Aiken, Allison C.; Koontz, Annette; Muradyan, Paytsar.

In: Geophysical Research Letters, 01.01.2018.

Research output: Contribution to journalArticle

Zuidema, P, Sedlacek, AJ, Flynn, C, Springston, S, Delgadillo, R, Zhang, J, Aiken, AC, Koontz, A & Muradyan, P 2018, 'The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky', Geophysical Research Letters. https://doi.org/10.1002/2017GL076926
Zuidema, Paquita ; Sedlacek, Arthur J. ; Flynn, Connor ; Springston, Stephen ; Delgadillo, Rodrigo ; Zhang, Jianhao ; Aiken, Allison C. ; Koontz, Annette ; Muradyan, Paytsar. / The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky. In: Geophysical Research Letters. 2018.
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