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

Abstract

Observations from June through 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. rBC mass concentrations, light absorption coefficients, and cloud condensation nuclei concentrations vary in concert and synoptically, peaking in August. Derived mass absorption cross-sections using light absorptioin coefficients at three wavelengths as a function of rBC mass indirectly indicate the presence of other light-absorbing organic aerosols (e.g., brown carbon), most pronounced in June. A filter-based estimate of single-scattering-albedo increases systematically from August to October, also apparent in 2017. 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 in the free-troposphere 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 of 2016, is investigated further. Back trajectories indicate the boundary layer transport was directly westward from the African continent, which is unusual in August.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3];  [2]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [4];  [3];  [5]
  1. Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami FL USA
  2. Brookhaven National Laboratory, Brookhaven NY USA
  3. Pacific Northwest National Laboratory, Richland WA USA
  4. Los Alamos National Laboratory, Los Alamos NM USA
  5. Argonne National Laboratory, Argonne IL USA
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1455314
Report Number(s):
PNNL-SA-131497
Journal ID: ISSN 0094-8276; KP1704010
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geophysical Research Letters; Journal Volume: 45; Journal Issue: 9
Country of Publication:
United States
Language:
English

Citation Formats

Zuidema, Paquita, Sedlacek, Arthur J., Flynn, Connor, Springston, Stephen, Delgadillo, Rodrigo, Zhang, Jianhao, Aiken, Allison C., Koontz, Annette, and Muradyan, Paytsar. The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky. United States: N. p., 2018. Web. doi: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. United States. doi:10.1002/2017GL076926.
Zuidema, Paquita, Sedlacek, Arthur J., Flynn, Connor, Springston, Stephen, Delgadillo, Rodrigo, Zhang, Jianhao, Aiken, Allison C., Koontz, Annette, and Muradyan, Paytsar. Fri . "The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky". United States. doi:10.1002/2017GL076926.
@article{osti_1455314,
title = {The Ascension Island Boundary Layer in the Remote Southeast Atlantic is Often Smoky},
author = {Zuidema, Paquita and Sedlacek, Arthur J. and Flynn, Connor and Springston, Stephen and Delgadillo, Rodrigo and Zhang, Jianhao and Aiken, Allison C. and Koontz, Annette and Muradyan, Paytsar},
abstractNote = {Observations from June through 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. rBC mass concentrations, light absorption coefficients, and cloud condensation nuclei concentrations vary in concert and synoptically, peaking in August. Derived mass absorption cross-sections using light absorptioin coefficients at three wavelengths as a function of rBC mass indirectly indicate the presence of other light-absorbing organic aerosols (e.g., brown carbon), most pronounced in June. A filter-based estimate of single-scattering-albedo increases systematically from August to October, also apparent in 2017. 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 in the free-troposphere 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 of 2016, is investigated further. Back trajectories indicate the boundary layer transport was directly westward from the African continent, which is unusual in August.},
doi = {10.1002/2017GL076926},
journal = {Geophysical Research Letters},
number = 9,
volume = 45,
place = {United States},
year = {Fri May 11 00:00:00 EDT 2018},
month = {Fri May 11 00:00:00 EDT 2018}
}