The extreme forest fires in California/Oregon in 2020: Aerosol optical and physical properties and comparisons of aged versus fresh smoke

Eck, T. F.; Holben, B. N.; Reid, Jeffrey S.; Sinyuk, A.; Giles, D. M.; Arola, Antti; Slutsker, I.; Schafer, J. S.; Sorokin, M. G.; Smirnov, A.; LaRosa, A. D.; Kraft, J.; Reid, Elizabeth A.; O’Neill, Norman T.; Welton, Ellsworth J.; Menendez, Arsenio R.

doi:10.1016/j.atmosenv.2023.119798

Cited by 11 publications

(9 citation statements)

References 96 publications

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“…To avoid potential interference from dust aerosols on smoke analysis, we excluded the Sahel region bounding the Sahara Desert from this study. The selected smoke aerosol analysis regions, along with detected fire counts from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite in 2018, are presented in Fig 2 . This study focused on the entire year of 2018, a year marked by one of highest monthly average AOD during the summer over North America (Eck et al, 2023). The EPIC dataset exhibited no temporal gaps, and ample AERONET and CALIOP data were accessible.…”

Section: Study Regionsmentioning

confidence: 99%

Light-absorbing black carbon and brown carbon components of smoke aerosol from DSCOVR EPIC measurements over North America and Central Africa

Choi,

Lyapustin,

Schuster

et al. 2024

Preprint

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Abstract. Wildfires and agricultural burning generate seemingly increasing smoke aerosol emissions, impacting societal and natural ecosystems. To understand smoke’s effects on climate and public health, we analyzed the spatiotemporal distribution of smoke aerosols, focusing on two major light-absorbing components, black carbon (BC) and brown carbon (BrC) aerosols. Using NASA’s Earth Polychromatic Imaging Camera (EPIC) instrument aboard the NOAA’s Deep Space Climate Observatory (DSCOVR) spacecraft, we inferred BC and BrC volume fractions and particle mass concentrations based on spectral absorption provided by the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm with 1–2 hours temporal resolution and ~10 km spatial resolution over North America and Central Africa. Our analyses of regional smoke properties reveal distinct characteristics for aerosol optical depth (AOD) at 443 nm, spectral single scattering albedo (SSA), aerosol layer height (ALH), and BC and BrC amounts. Smoke cases in North America show extremely high AOD up to 6, with elevated ALH (6–7 km) and significant BrC components up to 250 mg/m2 along the transport paths, whereas the smoke aerosols in Central Africa exhibited stronger light absorption (i.e., lower SSA) and lower AOD, resulting in higher BC mass concentrations and similar BrC mass concentrations than the cases in North America. Seasonal burning source locations in Central Africa following the seasonal shift of Inter Tropical Convergence Zone and diurnal variations in smoke amounts were also captured. Comparison of retrieved AOD443, SSA443, SSA680, and ALH with collocated AERONET and CALIOP measurements shows agreement with rmse of 0.2, 0.03–0.04, 0.02–0.04, and 0.8–1.3 km, respectively. Analysis of spatiotemporally average reveals distinct geographical characteristics in smoke properties closely linked to burning types and meteorological conditions. Forest wildfires over western North America generated smoke with small BC volume fraction of 0.011 and high ALH with large variability (2.2 ± 1.2 km), whereas smoke from wildfires and agricultural burning over Mexico region shows more absorption and low ALH. Smoke from savanna fires over Central Africa has the most absorption with high BC volume fraction (0.015) and low ALH with small variation (1.8 ± 0.6 km) among the analyzed regions. Tropical forest smoke was less absorbing and had a high variance in ALH. We also quantify the estimation uncertainties related to the assumptions of BC and BrC refractive indices. The MAIAC EPIC smoke properties with BC and BrC volume and mass fractions and assessment of layer height provide observational constraints for radiative forcing modeling and air quality and health studies.

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Section: Study Regionsmentioning

confidence: 99%

Light-absorbing black carbon and brown carbon components of smoke aerosol from DSCOVR EPIC measurements over North America and Central Africa

Choi,

Lyapustin,

Schuster

et al. 2024

Preprint

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“…23,24 As the smoke plume evolves, the aerosols undergo aging processes that change their physical and chemical composition. 23,[25][26][27][28][29] Observations of aging smoke have identified trends associated with the lifetime of smoke in the atmosphere. 23,25,[29][30][31] Chemical and optical properties evolve rapidly within a smoke plume as smoke aerosols propagate from the source of the fire.…”

Section: Simulated Ground-based Polarimetric Responsesmentioning

confidence: 99%

“…23,[25][26][27][28][29] Observations of aging smoke have identified trends associated with the lifetime of smoke in the atmosphere. 23,25,[29][30][31] Chemical and optical properties evolve rapidly within a smoke plume as smoke aerosols propagate from the source of the fire. 23,30 The gases emitted during the combustion phase can condense as the aerosols move away from the fire, while at the same time primary compounds of aerosols can evaporate over distances.…”

Section: Simulated Ground-based Polarimetric Responsesmentioning

confidence: 99%

“…As the plume persists in the atmosphere and brown carbon increases, higher scattering signatures are expected. Eck et al (2023) showed that smoke ≈ 4-5 days old had a strong spectral single scattering albedo signature, suggesting smoke of this age is primarily brown carbon. 29 Accumulation (i.e.…”

Section: Simulated Ground-based Polarimetric Responsesmentioning

confidence: 99%

“…Eck et al (2023) showed that smoke ≈ 4-5 days old had a strong spectral single scattering albedo signature, suggesting smoke of this age is primarily brown carbon. 29 Accumulation (i.e. aerosols growing in size due to collisions) produces an increase in mean aerosol diameter throughout a smoke plume.…”

Section: Simulated Ground-based Polarimetric Responsesmentioning

confidence: 99%

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Simulating ground-based polarimetric responses using AirMSPI observations from the FIREX-AQ campaign

DeLeon,

Garay,

Kalashnikova

et al. 2023

Polarization Science and Remote Sensing XI

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Wildland fire smoke is one of the major sources of biomass-burning aerosols in the Earth's atmosphere. As the smoke plume evolves, the biomass-burning aerosols undergo aging processes that change their physical and chemical composition. Capturing rapid temporal changes is not suitable for satellites due to the time lapse between observations. Airborne remote sensing offers the ability to increase the spatial and temporal resolution of smoke plume observations compared to satellite observations. However, this increase in spatial and temporal resolution from airborne observations amplifies the need for better spatial coverage from ground-based instruments for validation. In the summer of 2019, the Airborne Multiangle Spectropolarimetric Imager (AirMSPI) was deployed during the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign on the NASA ER-2 high-altitude research aircraft. This aircraft performed multiple overpasses of the Williams Flats fire near the town of Spokane, Washington, USA, in August 2019, sampling smoke plumes at a georectifed spatial resolution of 10 m 2 . This work performs aerosol retrievals along the smoke plume observed during one flight on 7 August 2019. The retrieval methods used here follow those established by DeLeon et al. (in review ) using the Generalized Retrieval of Atmosphere and Surface Properties (GRASP). Two points along the plume were selected: one at 1.35km and the other at 3.78km from the fire source. The fraction of fine mode aerosols and single scattering albedo increased at the greater distance from this wildfire source. These retrieved aerosol properties were used to simulate ground-based polarimetry in ultraviolet, visible, and infrared wavebands. For all wavebands, the maximum degree of linear polarization (DoLP) decreased farther from the source. Notably, the ultraviolet wavebands retained a higher polarimetric signal farther from the source, compared to the visible and infrared. At 865 nm the DoLP decreased from 48.5% to 14.6%. At 355 nm the DoLP decreased from 33.6% to 22.5%. These polarimetric simulations are intended to inform instrument development for ground-based detection of wildfire smoke.

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Global changes in aerosol single scattering albedo during COVID-19

Ansari,

Ramachandran

2024

Atmospheric Environment

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The extreme forest fires in California/Oregon in 2020: Aerosol optical and physical properties and comparisons of aged versus fresh smoke

Cited by 11 publications

References 96 publications

Light-absorbing black carbon and brown carbon components of smoke aerosol from DSCOVR EPIC measurements over North America and Central Africa

Light-absorbing black carbon and brown carbon components of smoke aerosol from DSCOVR EPIC measurements over North America and Central Africa

Simulating ground-based polarimetric responses using AirMSPI observations from the FIREX-AQ campaign

Global changes in aerosol single scattering albedo during COVID-19

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