Comparing the simulated influence of biomass burning plumes on low-level clouds over the southeastern Atlantic under varying smoke conditions

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(8), P. 4591 - 4610

Published: April 18, 2024

Abstract. Biomass burning plumes are frequently transported over the southeast Atlantic (SEA) stratocumulus deck during southern African fire season (June–October). The bring large amounts of absorbing aerosols and enhanced moisture, which can trigger a rich set aerosol–cloud–radiation interactions with climatic consequences that still poorly understood. We use large-eddy simulation (LES) to explore disentangle individual impacts moisture on underlying clouds, marine boundary layer (MBL) evolution, stratocumulus-to-cumulus transition (SCT) for three different meteorological situations August 2017. For all cases, our LES shows SCT is driven by increased sea surface temperatures cloud-top entrainment as air advected towards Equator. In model, aerosol indirect effects, including drizzle production, have small influence modeled cloud evolution SCT, even when concentrations lowered background concentrations. contrast, local semi-direct i.e., absorption solar radiation in MBL, cause reduction cover lead speed-up particular daytime broken conditions, especially highly polluted situations. largest impact radiative budget comes from albedo: plume produces total average 3 d simulations. find accompanying an additional cooling effect about effect. Overall, there uncertainty associated effects biomass aerosols. A comparison between models common framework, combined constraints situ observations, could help reduce uncertainty.

Language: Английский

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Projecting Stratocumulus Transitions on the Albedo—Cloud Fraction Relationship Reveals Linearity of Albedo to Droplet Concentrations

Geophysical Research Letters, Journal Year: 2022, Volume and Issue: 49(20)

Published: Oct. 11, 2022

Abstract Satellite images show solid marine stratocumulus cloud decks (Sc) that break up over the remote oceans. The Sc breakup is initiated by precipitation and accompanied a strong reduction in radiative effect. Aerosol has been shown to delay postponing onset of precipitation, however its climatic effect uncertain. Here we introduce new approach allows us re‐cast currently observed cover albedo their counterfactual cleaner world, enabling first estimate due delayed breakup. Using simple approximation, forcing with respect pre‐industrial times −0.39 W m −2 . changes nearly linearly aerosol droplet concentration control on cover, suggesting potentially accelerated warming if current trend emissions continues.

Language: Английский

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Thin Clouds Control the Cloud Radiative Effect Along the Sc‐Cu Transition

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(10)

Published: May 14, 2024

Abstract In situ and spaceborne studies reveal the prevalence of thin clouds in major Stratocumulus‐to‐Cumulus Transition (SCT) regions. Using instantaneous satellite reanalysis data, this study investigates properties Southeast Pacific Ocean their impact on cloud radiative effect (CRE). Our findings demonstrate that are intrinsic to SCT. The overcast stratocumulus‐dominated regime exhibits a minimal presence clouds, which become notably prominent after breakup into cumulus‐dominated regime. dependence occurrence is also observed terms marine cold‐air outbreak parameter sea surface temperature. Thin at given cover significantly modulate shortwave (SW) longwave (LW) components CRE. SW CRE decreases by 46 %–65 % with increasing cover. They account for larger variance albedo than combined influence liquid water path effective radius. Furthermore, LW about 12 %–52 An increase fraction leads negative offset positive This compensation ranges from approximately 8 as much 19 50 These elucidate crucial role thus morphology, modulating underscore necessity accurate representation climate models.

Language: Английский

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Aerosol-induced closure of marine cloud cells: enhanced effects in the presence of precipitation

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(11), P. 6455 - 6476

Published: June 3, 2024

Abstract. The Weather Research Forecasting (WRF) version 4.3 model is configured within a Lagrangian framework to quantify the impact of aerosols on evolving cloud fields. Kilometer-scale simulations utilizing meteorological boundary conditions are based 10 case study days offering diverse meteorology during Aerosol and Cloud Experiments in Eastern North Atlantic (ACE-ENA). Measurements from aircraft, ground-based Atmosphere Radiation Measurement (ARM) site at Graciosa Island Azores, A-Train geostationary satellites utilized for validation, demonstrating good agreement with WRF-simulated aerosol properties. Higher concentration leads suppressed drizzle increased water content all days. These changes lead larger radiative cooling rates top, enhanced vertical velocity variance, horizontal wind speed near base lower-tropospheric inversion. As result, marine cell area expands, narrowing gap between shallow clouds increasing optical thickness, liquid content, top-of-atmosphere outgoing shortwave flux. While similar effects observed lightly non-raining clouds, they tend be smaller by comparison. show relationship expansion adjustments caused path fraction changes. positive scale as 74 % 51 %, respectively, relative Twomey effect. higher-resolution large-eddy may provide improved representation cloud-top mixing processes, these results emphasize importance addressing mesoscale cloud-state transitions quantification forcing that cannot attained traditional climate models.

Language: Английский

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Satellite-based analysis of top of atmosphere shortwave radiative forcing trend induced by biomass burning aerosols over South-Eastern Atlantic

npj Climate and Atmospheric Science, Journal Year: 2024, Volume and Issue: 7(1)

Published: June 12, 2024

Abstract This study investigates long-term changes in the shortwave direct aerosol radiative effect (DARE) at top of atmosphere (TOA) induced by biomass burning (BBA) transported from southern Africa to south-eastern Atlantic (SEA) stratocumulus region during extended fire seasons. The evolution since 2002 aerosol, cloud properties, and TOA outgoing radiation advanced passive satellite sensors are presented, as well observational trend clear-sky DARE clr retrieval all-sky all . Supplemented chemical transport model simulations, we estimate that has become more negative (−0.09 ± 0.06 W m −2 yr −1 ) due increased presence SEA. Meanwhile, positive ( + 0.04 0.15 aerosols cloudy sky regions. reveals capabilities capturing complex BBA-cloud-solar interactions for accurate forcing estimates projections.

Language: Английский

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A satellite-based analysis of semi-direct effects of biomass burning aerosols on fog and low-cloud dissipation in the Namib Desert

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(1), P. 491 - 510

Published: Jan. 15, 2025

Abstract. In the Namib Desert, fog is only regular water input and, thus, a crucial source for its fauna and flora. Each year, between June October, absorbing biomass burning aerosols (BBAs) overlie stratocumulus clouds in adjacent Southeast Atlantic. some synoptic settings, this layer of BBAs reaches Namibia desert, where it interacts with coastal low (FLCs). study, novel 15-year data set geostationary satellite observations FLC dissipation time Desert used, along reanalysis data, to better understand potential semi-direct effects on i.e., through adjustments atmospheric stability thermodynamics via interaction radiation. This done by investigating both day when FLCs dissolve synoptic-scale meteorology depending BBA loading. It found that significantly later high-BBA-loading days. are transported moist free-tropospheric air large-scale anticyclonic recirculation pattern. At surface, associated longwave heating strengthens continental heat low, which modifies circulation boundary moisture coastline, complicating attribution effects. During high-BBA days, vertical profiles temporal development temperatures highlight contrasting daytime nighttime processes modifying local inversion. These thought be driven greenhouse warming as result plumes absorption (only during daytime). A statistical learning framework used quantify meteorological influences time. The model able reproduce observed differences high- low-BBA days attributes these mainly circulation, near-surface temperature coastline. However, prone underfitting not majority variability. While does suggest patterns important dissipation, findings show how modify thermodynamics, shown sensitive. challenges disentangling aerosol cloud using invite detailed modeling analyses underlying processes, example, large-eddy simulations.

Language: Английский

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More biomass burning aerosol is being advected westward over the southern tropical Atlantic since 2003

The Science of The Total Environment, Journal Year: 2025, Volume and Issue: 965, P. 178506 - 178506

Published: Jan. 30, 2025

Language: Английский

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Burning conditions and transportation pathways determine biomass-burning aerosol properties in the Ascension Island marine boundary layer

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(4), P. 2333 - 2363

Published: Feb. 21, 2025

Abstract. African biomass-burning aerosol (BBA) in the southeast Atlantic Ocean (SEA) marine boundary layer (MBL) is an important contributor to Earth's radiation budget, yet its representation remains poorly constrained regional and global climate models. Data from Layered Smoke Interactions with Clouds (LASIC) field campaign on Ascension Island (7.95° S, 14.36° W) provide insight into how burning conditions, fuel type, transport pathways, atmospheric processing affect chemical, microphysical, optical properties of BBA between June September 2017. A total 10 individual plume events characterize seasonal evolution properties. Early-season inefficient fires, determined by low refractory black carbon above-background monoxide mixing ratios (rBC : ΔCO), led enhanced concentrations organic- sulfate-rich aerosols. Mid-season efficient higher rBC ΔCO values, rBC-enriched BBA. mix fires later season resulted conflicting Prolonged (∼ d) through MBL lower free troposphere (FT) facilitated chemical aqueous-phase processing, which a reduction organic mass concentrations. This (OA) (OA rBC) (2–5) compared values (5–15) nearby FT. These cloud oxidation processes yield more light-absorbing explain notably single-scattering albedo at 530 nm (SSA530) (< 0.80) observed MBL. study establishes robust correlation SSA530 OA across FT, underscoring dependency composition.

Language: Английский

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Aerosol impacts on the West African Monsoon

Elsevier eBooks, Journal Year: 2025, Volume and Issue: unknown, P. 65 - 92

Published: Jan. 1, 2025

Language: Английский

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Intercomparison of airborne and surface-based measurements during the CLARIFY, ORACLES and LASIC field experiments

Atmospheric measurement techniques, Journal Year: 2022, Volume and Issue: 15(21), P. 6329 - 6371

Published: Nov. 3, 2022

Abstract. Data are presented from intercomparisons between two research aircraft, the FAAM BAe-146 and NASA Lockheed P3, surface-based DOE (Department of Energy) ARM (Atmospheric Radiation Measurement) Mobile Facility at Ascension Island (8∘ S, 14.5∘ W; a remote island in mid-Atlantic). These took place 17 August to 5 September 2017, during African biomass burning (BB) season. The primary motivation was give confidence use data multiple platforms with which evaluate numerical climate models. three were involved CLouds–Aerosol–Radiation Interaction Forcing for Year 2017 (CLARIFY-2017), ObseRvations Aerosols above CLouds their intEractionS (ORACLES), Layered Atlantic Smoke Interactions Clouds (LASIC) field experiments. Comparisons flight segments on 6 d where flew alongside facility presented, along comparisons wing-tip-to-wing-tip P3 18 2017. intercomparison sampled relatively clean atmosphere overlying moderately polluted boundary layer, while six fly-bys site both conditions 2–4 km upwind. We compare validate characterisations aerosol physical, chemical optical properties as well atmospheric radiation cloud microphysics platforms. assess performance measurement instrumentation field, under sampling not tightly controlled laboratory measurements calibrations performed. Solar compared enough permit radiative closure studies. Optical absorption coefficient all within uncertainty limits, although absolute magnitudes too low (<10 Mm−1) fully support comparison Ångström exponents. Aerosol airborne more comparable than aircraft-to-ground observations. Scattering observations adequately platforms, but agreement ground-based worse, potentially caused by small differences or actual population over land. Chemical composition followed similar pattern, better Thermodynamics, microphysical generally agreed given uncertainties.

Language: Английский

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