Aging of Atmospheric Brown Carbon Aerosol

Hems, Rachel F.; Schnitzler, Elijah G.; Liu-Kang, Carolyn; Cappa, Christopher D.; Abbatt, Jonathan P. D.

doi:10.1021/acsearthspacechem.0c00346

Cited by 140 publications

(200 citation statements)

References 288 publications

(969 reference statements)

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“…As potential contributors to lightabsorption of BrC, only two fluorescence fractions of humic-like substances are found in PM 2.5 , whereas four fluorescence fractions (three types of humic-like substances and one type of tyrosine/protein-like substances) are identified in cloud water, most likely attributed to secondary production. While extensive laboratory evidence indicated the possible formation of BrC in aqueous phase (Hems et al, 2021), our study represents the first attempt to show the possibility under real cloud condition.…”

Section: Discussionmentioning

confidence: 86%

The optical properties and in-situ observational evidence for the formation of brown carbon in cloud

Guo

Yang

et al. 2021

Preprint

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Abstract. Atmospheric brown carbon (BrC) makes a substantial contribution to aerosol light-absorbing and thus the global radiative forcing. Although BrC may change the lifetime of the cloud and ultimately affect precipitation, little is known regarding the optical properties and formation of BrC in the cloud. In the present study, the light-absorption properties of cloud droplet residual (cloud RES) were measured by coupled a ground-based counterflow virtual impactor (GCVI) and an Aethalometer (AE-33), in addition to the cloud interstitial (cloud INT) and ambient (cloud-free) particles by PM2.5 inlet-AE-33, at Mt. Tianjing (1690 m a.s.l.), a remote mountain site in southern China, from November to December 2020. Meanwhile, the light-absorption and fluorescence properties of water-soluble organic carbon (WSOC) in the collected cloud water and PM2.5 samples were also obtained, associated with the concentration of water-soluble ions. The mean light-absorption coefficient (Abs370) of the cloud RES, cloud INT, and cloud-free particles were 0.25 ± 0.15, 1.16 ± 1.14, and 1.47 ± 1.23 Mm−1, respectively. The Abs365 of WSOC was 0.11 ± 0.08 Mm−1 in cloud water and 0.40 ± 0.31 Mm−1 in PM2.5, and the corresponding mass absorption efficiency (MAE365) was 0.17 ± 0.07 and 0.31 ± 0.21 m2·g−1, respectively. A comparison of the light-absorption coefficient between BrC in the cloud RES/cloud INT and WSOC in cloud water/PM2.5 indicates a considerable contribution (48–75 %) of water-insoluble BrC to total BrC light-absorption. Secondary BrC estimated by minimum R squared (MRS) method dominated the total BrC in cloud RES (67–85 %), rather than in the cloud-free (11–16 %) and cloud INT (9–23 %) particles. It may indicate the formation of secondary BrC during cloud processing. Supporting evidence includes the enhanced WSOC and dominant contribution of secondary formation/biomass burning factor (> 80 %) to Abs365 in cloud water provided by Positive Matrix Factorization (PMF) analysis. In addition, we showed that the light-absorption of BrC in cloud water was closely related to humic-like substances and tyrosine/proteins-like substances (r > 0.63, p < 0.01), whereas only humic-like substances for PM2.5, as identified by excitation-emission matrix fluorescence spectroscopy.

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Section: Discussionmentioning

confidence: 86%

The optical properties and in-situ observational evidence for the formation of brown carbon in cloud

Guo

Yang

et al. 2021

Preprint

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“…These plumes can be lofted into a warm conveyor belt preceeding a cold front from an associated cyclone, which is followed by the entrainment of a cold descending air stream (from the same cyclone) that ultimately results in the air parcels containing continental emissions reaching the lower altitudes of the Eastern North Atlantic (Owen et al, 2006;Zheng et al, 2020b). The transported aerosol undergoes substantial atmospheric aging through photochemical reactions (Hems et al, 2021), gas-particle partitioning (Vakkari et al, 2018), and coagulation (Ramnarine et al, 2019) processes as it travels 315 across the Atlantic ocean and descends into the MBL during the DI events.…”

Section: Particle-type Classification 220mentioning

confidence: 99%

Impact of Dry Intrusion Events on Composition and Mixing State of Particles During Winter ACE-ENA Study

Tomlin

Jankowski

Veghte

et al. 2021

Preprint

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Abstract. Long-range transport of continental emission has far reaching influence over remote regions resulting in substantial change in the size, morphology, and composition of the local aerosol population and cloud condensation nuclei (CCN) budget. Here, we investigate the physiochemical properties of atmospheric particles collected onboard a research aircraft flown over the Azores during the winter 2018 Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA) campaign. Particles were collected within the marine boundary layer (MBL) and free troposphere (FT), after long-range atmospheric transport episodes facilitated by dry intrusion (DI) events. Chemical and physical properties of individual particles were investigated using complementary capabilities of computer-controlled scanning electron microscopy and X-ray spectro-microscopy to probe particle external and internal mixing state characteristics in the context of real-time measurements of aerosol size distribution, cloud condensation nuclei (CCN) concentration, and back trajectory calculations. While carbonaceous particles were found to be the dominant particle-type in the region, changes in the percent contribution of organics across the particle population (i.e., external mixing) shifted from 68 % to 43 % in the MBL and from 92 % to 46 % in FT samples during DI events. This change in carbonaceous contribution is counterbalanced by the increase of inorganics from 32 % to 57 % in the MBL and 8 % to 55 % in FT. The quantification of organic volume fraction (OVF) of individual particles derived from X-ray spectro-microscopy, which relates to the multi-component internal composition of individual particles, showed a factor of 2.06 ± 0.16 and 1.11 ± 0.04 increase in the MBL and FT, respectively, among DI samples. We show that supplying particle OVF into the κ-Köhler equation can be used as a good approximation of field measured in-situ CCN concentrations. We also report changes in the κ values between κMBL, non-DI = 0.48 to κMBL, DI = 0.41 and κFT, non-DI = 0.36 to κFT, DI = 0.33, which is consistent with enhancements in OVF followed by the DI episodes. Our observations suggest that entrainment of particles from long-range continental sources alters the mixing state population and CCN properties of aerosol in the region. The work presented here provides field observation data that can inform atmospheric models that simulate sources and particle composition in the Eastern North Atlantic.

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“…Wildfire smoke particles, mainly consisting of brown carbon with a few percent of black carbon (Hems et al, 2021), considerably absorb solar radiation and can perturb shortwave and longwave radiative fluxes, and thus dynamical processes. Several Australian smoke plumes were found to significantly alter the dynamic circulation in the lower stratosphere (Khaykin et al, 2020;Kablick et al, 2020;Allen et al, 2020;Lestrelin et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Australian wildfire smoke in the stratosphere: the decay phase in 2020/21 and impact on ozone depletion

Ohneiser¹,

Ansmann²,

Kaifler³

et al. 2022

Preprint

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Abstract. Record-breaking wildfires raged in southeastern Australia in late December 2019 and early January 2020. Rather strong pyrocumulonimbus (pyroCb) convection developed over the fire areas and lifted enormous amounts of biomass-burning smoke into the tropopause region and caused the strongest wildfire-related stratospheric aerosol perturbation ever observed around the globe. We discuss the geometrical, optical, and microphyscial properties of the stratospheric smoke layers and the decay of this major stratospheric perturbation. A multiwavelength polarization Raman lidar at Punta Arenas (53.2° S, 70.9° W), southern Chile, and an elastic-backscatter Raman lidar at Río Grande (53.8° S, 67.7° W) in southern Argentina were operated to monitor the major record-breaking event until the end of 2021. These lidar measurements can be regarded as representative for mid to high latitudes in the Southern Hemisphere. A unique dynamical feature, an anticyclonic, smoke-filled vortex with 1000 km horizontal width and 5 km vertical extent, which ascended by about 500 m per day, was observed over the full last week of January 2020. The key results of the long-term study are as follows: The smoke layers extended, on average, from 9 to 24 km in height. The smoke partly ascended to more than 30 km height as a result of self-lifting processes. Clear signs of a smoke impact on the record-breaking ozone hole over Antarctica in September–November 2020 were found. A slow decay of the stratospheric perturbation detected by means of the 532 nm aerosol optical thickness (AOT) yielded an e-folding decay time of 19–20 months. The maximum smoke AOT was around 1.0 over Punta Arenas in January 2020 and thus two to three orders of magnitude above the stratospheric aerosol background of 0.005. After two months with strongly varying smoke conditions, the 532 nm AOT decreased to 0.03–0.06 from March–December 2020 and to 0.015–0.03 throughout 2021. The particle extinction coefficients were in the range of 10–75 Mm−1 in January 2020, and later on mostly between 1 and 5 Mm−1. Combined lidar-photometer retrievals revealed typical smoke extinction-to-backscatter ratios of 69 ±19 sr (at 355 nm), 91 ± 17 sr (at 532 nm), and 120 ± 22 sr (at 1064 nm). An ozone reduction of 20–25 % in the 15–22 km height range was observed over Antarctic and New Zealand ozonesonde stations in the smoke-polluted air with particle surface area concentrations of 1–5 μm2 cm−3.

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Aging of Atmospheric Brown Carbon Aerosol

Cited by 140 publications

References 288 publications

The optical properties and in-situ observational evidence for the formation of brown carbon in cloud

The optical properties and in-situ observational evidence for the formation of brown carbon in cloud

Impact of Dry Intrusion Events on Composition and Mixing State of Particles During Winter ACE-ENA Study

Australian wildfire smoke in the stratosphere: the decay phase in 2020/21 and impact on ozone depletion

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