Preprints
https://doi.org/10.5194/acp-2022-545
https://doi.org/10.5194/acp-2022-545
 
29 Aug 2022
29 Aug 2022
Status: this preprint is currently under review for the journal ACP.

An Evaluation of Biomass Burning Aerosol Mass, Extinction, and Size Distribution in GEOS using Observations from CAMP2Ex

Allison B. Marquardt Collow1,2, Virginie Buchard1,2, Peter R. Colarco2, Arlindo M. da Silva2, Ravi Govindaraju2,3, Edward P. Nowottnick2, Sharon Burton4, Richard Ferrare4, Chris Hostetler4, and Luke Ziemba4 Allison B. Marquardt Collow et al.
  • 1University of Maryland Baltimore County, Baltimore, Maryland, USA
  • 2NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 3Science Systems and Applications, Inc., Lanham, Maryland, USA
  • 4NASA Langley Research Center, Hampton, Virginia, USA

Abstract. Biomass burning aerosol impacts aspects of the atmosphere and Earth system through radiative forcing, serving as cloud condensation nuclei, and air quality. Despite its importance, the representation of biomass burning aerosol is not always accurate in numerical weather prediction and climate models or reanalysis products. Using observations collected as part of the Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex) in August through October of 2019, aerosol concentration and optical properties are evaluated within the Goddard Earth Observing System (GEOS) and its underlying aerosol module, GOCART. In the operational configuration, GEOS assimilates aerosol optical depth observations at 550 nm to constrain aerosol fields. Particularly for biomass burning aerosol, without the assimilation of aerosol optical depth, aerosol extinction is underestimated compared to observations collected in the Philippines region during the CAMP2Ex campaign. The assimilation process adds excessive amounts of carbon to account for the underestimated extinction, resulting in positive biases in the mass of black and organic carbon, especially within the boundary layer, relative to in situ observations from the Langley Aerosol Research Group Experiment. Counteracting this, GEOS is deficient in sulphate and nitrate aerosol just above the boundary layer. Aside from aerosol mass, extinction within GEOS is a function of ambient relative humidity and an assumed particle size distribution. The relationship between dry and ambient extinction in GEOS reveals that hygroscopic growth is too aggressive within the model for biomass burning aerosol. An additional concern lies in the assumed particle size distribution for GEOS, which has a mode radius that is too small for organic carbon. Variability in the observed particle size distribution for biomass burning aerosol within a single flight also illuminates the fact that a single assumed particle size distribution is not sufficient and that for a proper representation, a more advanced aerosol module with GEOS may be necessary.

Allison B. Marquardt Collow et al.

Status: open (until 10 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-545', Anonymous Referee #1, 14 Sep 2022 reply
  • RC2: 'Comment on acp-2022-545', Anonymous Referee #2, 27 Sep 2022 reply

Allison B. Marquardt Collow et al.

Allison B. Marquardt Collow et al.

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Short summary
Biomass burning aerosol impacts aspects of the atmosphere and Earth system through radiative forcing, serving as cloud condensation nuclei, and air quality. Despite its importance, the representation of biomass burning aerosol is not always accurate in models. Field campaign observations from CAMP2Ex are used to evaluate the mass and extinction of aerosols in the GEOS model. Notable biases in the model illuminate areas of future development with GEOS and the underlying GOCART aerosol module.
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