Abstract

Abstract. Among the various measurement approaches to quantify the light absorption coefficient (Babs), filter-based absorption photometers are dominant in monitoring networks around the globe. Numerous correction algorithms have been introduced to minimize the artifacts due to the presence of the filter in these instruments. However, from our recent studies conducted during the Fire Influence on Regional and Global Environments Experiment (FIREX) laboratory campaign, corrected filter-based Babs remains biased high by roughly a factor of 2.5 when compared to a reference value using a photoacoustic instrument for biomass burning emissions. Similar overestimations of Babs from filter-based instruments exist when implementing the algorithms on 6 months of ambient data from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) user facility from 2013 (factor of roughly 3). In both datasets, we observed an apparent dependency on single-scattering albedo (SSA) and the absorption Ångström exponent (AAE) in the agreement between Babs based on existing correction factors and the reference Babs. Consequently, we developed a new correction approach that is applicable to any filter-based absorption photometer that includes light transmission from the filter-based instrument as well as the derived AAE and SSA. For the FIREX and SGP datasets, our algorithm results in good agreement between all corrected filter-based Babs values from different filter-based instruments and the reference (slopes ≈1 and R2≈0.98 for biomass burning aerosols and slopes ≈1.05 and R2≈0.65 for ambient aerosols). Moreover, for both the corrected Babs and the derived optical properties (SSA and AAE), our new algorithms work better or at least as well as the two common correction algorithms applied to a particle soot absorption photometer (PSAP). The uncertainty of the new correction algorithm is estimated to be ∼10 %, considering the measurement uncertainties of the operated instruments. Therefore, our correction algorithm is applicable to any filter-based absorption photometer and has the potential to “standardize” reported results across any filter-based instrument.

Highlights

  • Light-absorbing atmospheric aerosols directly affect the Earth’s energy budget by absorbing solar radiation, leading to a warming effect when they are suspended in the atmosphere and to the melting of snow and ice following deposition (Bond and Bergstrom, 2006; Boucher, 2015; Horvath, 1993)

  • We developed the general form for our correction algorithms using Continuous Light Absorption Photometer (CLAP) and Tricolor Absorption Photometer (TAP) measurements collected from biomass burning (65 fires in total) during the Fire Influence on Regional to Global Environments Experiment (FIREX) laboratory campaign in 2016

  • We focus on the results of the CLAP in the main text because a CLAP is the only instrument common to deployments for both FIREX and Southern Great Plains (SGP)

Read more

Summary

Introduction

Light-absorbing atmospheric aerosols directly affect the Earth’s energy budget by absorbing solar radiation, leading to a warming effect when they are suspended in the atmosphere and to the melting of snow and ice following deposition (Bond and Bergstrom, 2006; Boucher, 2015; Horvath, 1993). Scientists have conducted field experiments around the globe to investigate how absorbing aerosols influence the atmospheric radiative balance and interact with clouds (e.g., Andrews et al, 2011; Cappa et al, 2016; Lack et al, 2008b; Rajesh and Ramachandran, 2018; Schwarz et al, 2008) These experiments may be performed at fixed stations (e.g., observation sites maintained by the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program or the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division – GMD) or on mobile platforms (e.g., car trailer, aircraft, ship), typically involving measurements of aerosol chemical, physical, and optical properties. Li et al.: Development of a new correction algorithm climate model simulations (e.g., Chen et al, 2019; Vignati et al, 2010), while intensive measurements of Babs during short-term field campaigns allow for the investigation of optical properties that govern features of aerosol forcing (e.g., McMeeking et al, 2014; Olson et al, 2015)

Methods
Results
Conclusion
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call