Ultra-clean and smoky marine boundary layers frequently occur in the same season over the southeast Atlantic

Pennypacker, Sam; Diamond, Michael; Wood, Robert

doi:https://doi.org/10.5194/acp-20-2341-2020

Articles | Volume 20, issue 4

https://doi.org/10.5194/acp-20-2341-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

New observations and related modelling studies of the aerosol–cloud–climate...

https://doi.org/10.5194/acp-20-2341-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 4

Research article

| Highlight paper

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27 Feb 2020

Research article | Highlight paper |

| 27 Feb 2020

Ultra-clean and smoky marine boundary layers frequently occur in the same season over the southeast Atlantic

Sam Pennypacker, Michael Diamond, and Robert Wood

Supplement

https://doi.org/10.5194/acp-20-2341-2020-supplement

Data sets

Ultra-High Sensitivity Aerosol Spectrometer (AOSUHSAS). 2016-04-23 to 2017-11-01 Atmospheric Radiation Measurement (ARM) https://doi.org/10.5439/1095587

Condensation Particle Counter (AOSCPCU). 2016-05-20 to 2017-11-03 Atmospheric Radiation Measurement (ARM) https://doi.org/10.5439/1046186

MWR Retrievals (MWRRET1LILJCLOU). 2016-05-21 to 2017-11-01 Atmospheric Radiation Measurement (ARM) https://doi.org/10.5439/1027369

Total Sky Imager (TSISKYCOVER). 2016-05-02 to 2017-10-31 Atmospheric Radiation Measurement (ARM) https://doi.org/10.5439/1025308

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Short summary

Using observations from instruments deployed to a small island in the southeast Atlantic, we study days when the atmospheric concentrations of particles near the surface are exceptionally low. Interestingly, these ultra-clean boundary layers occur in the same months as the smokiest boundary layers associated with biomass burning in Africa. We find evidence that enhancements in drizzle scavenging, on top of a seasonal maximum in cloudiness and precipitation, likely drive these conditions.