Humidified single-scattering albedometer (H-CAPS-PM<sub>SSA</sub>): Design, data analysis, and validation

Carrico, Christian M.; Capek, Tyler; Gorkowski, Kyle; Lam, Jared; Gulick, Sabina; Karacaoglu, Jaimy; Lee, James E.; Dungan, Charlotte; Aiken, A. C.; Onasch, T. B.; Freedman, Andrew; Mazzoleni, Cláudio; Dubey, M. K.

doi:10.1080/02786826.2021.1895430

Cited by 4 publications

(4 citation statements)

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“…We probe the humidity-dependent BrC optical properties with a novel humidified single-scattering albedometer. 29 Light absorption enhancements increase with relative humidity for the BrC mimics, which reproduces the behavior of hygroscopic BrC aerosol. On the whole, the higher humidity increases the single-scattering albedo of BrC, but the absorption enhancements increase the atmospheric heating rate, a warming feedback.…”

Section: Introductionsupporting

confidence: 63%

“…The optical instruments consisted of a three-wavelength photoacoustic soot spectrometer (405, 532, and 781 nm, PASS, Droplet Measurement Technology, Longmont CO, USA) and a cavity-attenuated phase-shift single-scattering albedo particulate matter (PM) monitor (CAPS-PM SSA , Aerodyne Research, Inc., Billerica, MA, USA). The CAPS-PM SSA instrument was coupled with a humidification system as described in Carrico et al, 29 which allows for humidity-dependent optical measurements.…”

Section: Resultsmentioning

confidence: 99%

“…These particles can uptake water as humidity increases, causing changes in particle size, composition, and effective refractive index . To explore this effect on the BrC mimics, we measured the change in SSA with humidity (Figure a) as measured by the humidified-cavity-attenuated phase-shift single-scattering albedo particulate matter monitor (H-CAPS-PM SSA ) . The measured extinction, scattering, and absorption enhancements are shown in the SI.…”

Section: Resultsmentioning

confidence: 99%

“…Water alters the optical properties of the mixed BrC particles depending on their affinity. We probe the humidity-dependent BrC optical properties with a novel humidified single-scattering albedometer . Light absorption enhancements increase with relative humidity for the BrC mimics, which reproduces the behavior of hygroscopic BrC aerosol.…”

Section: Introductionmentioning

confidence: 80%

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Complexities in Modeling Organic Aerosol Light Absorption

et al. 2022

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Aerosol particles dynamically evolve in the atmosphere by physicochemical interactions with sunlight, trace chemical species, and water. Current modeling approaches fix properties such as aerosol refractive index, introducing spatial and temporal errors in the radiative impacts. Further progress requires a process-level description of the refractive indices as the particles age and experience physicochemical transformations. We present two multivariate modeling approaches of light absorption by brown carbon (BrC). The initial approach was to extend the modeling framework of the refractive index at 589 nm ( n D ), but that result was insufficient. We developed a second multivariate model using aromatic rings and functional groups to predict the imaginary part of the complex refractive index. This second model agreed better with measured spectral absorption peaks, showing promise for a simplified treatment of BrC optics. In addition to absorption, organic functionalities also alter the water affinity of the molecules, leading to a hygroscopic uptake and increased light absorption, which we show through measurements and modeling.

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Section: Introductionsupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 80%

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