Anthropogenic Land Use and Land Cover Changes—A Review on Its Environmental Consequences and Climate Change

Journal of the Indian Society of Remote Sensing, Год журнала: 2022, Номер 50(8), С. 1615 - 1640

Опубликована: Июнь 7, 2022

Язык: Английский

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Cloud processing and weeklong ageing affect biomass burning aerosol properties over the south-eastern Atlantic

Communications Earth & Environment, Год журнала: 2022, Номер 3(1)

Опубликована: Авг. 18, 2022

Abstract Southern Africa produces a third of global biomass burning emissions, which have long atmospheric lifetime and influence regional radiation balance climate. Here, we use airmass trajectories to link different aircraft observations investigate the evolution biomass-burning aerosols during their westward transport from over south-eastern Atlantic, where semi-permanent stratocumulus cloud deck is located. Our results show secondary organic aerosol formation initial 3 days transport, followed by decreases in via photolysis before reaching equilibrium. Aerosol absorption wavelength dependency with ageing, due an increase particle size photochemical bleaching brown carbon. Cloud processing, including aqueous-phase reaction scavenging, contributes oxidation aerosols, while it strongly reduces large diameter particles single-scattering albedo aerosols. Together, these processes resulted marine boundary layer fewer yet more oxidized absorbing

Язык: Английский

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First TanSat CO2 retrieval over land and ocean using both nadir and glint spectroscopy

Remote Sensing of Environment, Год журнала: 2024, Номер 304, С. 114053 - 114053

Опубликована: Фев. 19, 2024

Язык: Английский

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A meteorological overview of the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign over the southeastern Atlantic during 2016–2018: Part 1 – Climatology

Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(22), С. 16689 - 16707

Опубликована: Ноя. 16, 2021

Abstract. In 2016–2018, the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) project undertook 3-month-long deployments to southeastern (SE) Atlantic Ocean using research aircraft better understand impact biomass burning (BB) aerosol transport SE on climate. this (part 1 meteorological overview) paper, climatological features at monthly timescales are investigated. The southern African easterly jet (AEJ-S), defined as zonal easterlies over 600–700 hPa exceeding 6 m s−1 around 5–15∘ S, is a characteristic feature mid-level circulation Africa that was also during deployment months August 2017, September 2016, October 2018. Climatologically, AEJ-S develops lower altitudes (∼ 3 km; 700 hPa) between 5–10∘ S in August, while it 4 km 600 further south (5–15∘ S) October, largely driven by strong sensible heating plateau. Notable anomalous characteristics months, compared climatology (2000–2018), include following: (1) weaker than mean, with an additional upper-level aloft km) 10∘ S. 2017 drier climatology, stronger Benguela low-level (LLJ) 925–950 along Namibian coast Atlantic. Consistent this, anticyclone closer mean. (2) During intensity similar although heat low vertical motion land slightly climatology. LLJ large-scale were (3) 2018, anticyclone. 2018 wetter coastal region all sea surface temperatures (SST) warmer means, but mean cloud fraction only noticeably reduced 2017. A weak can explain offshore black carbon (BC) mixing ratios within European Centre for Medium-Range Weather Forecasts (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) reanalysis, BC peak altitude, 2–3 km, below AEJ-S. wave disturbance associated weakening through reduction strength

Язык: Английский

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Cloud adjustments from large-scale smoke–circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition

Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(18), С. 12113 - 12151

Опубликована: Сен. 19, 2022

Abstract. Smoke from southern Africa blankets the southeastern Atlantic Ocean June to October, producing strong and competing aerosol radiative effects. effects on transition between overcast stratocumulus scattered cumulus clouds are investigated along a Lagrangian (air-mass-following) trajectory in regional climate large eddy simulation models. Results compared with observations three recent field campaigns that took place August 2017: ObseRvations of Aerosols above CLouds their intEractionS (ORACLES), Aerosol Radiative Impacts Forcing: Year 2017 (CLARIFY), Layered Interactions Clouds (LASIC). The case study is set up around joint ORACLES–CLARIFY flight near Ascension Island 18 2017. sampled upstream an ORACLES 15 likely entrained into marine boundary layer later during flight. first simulated WRF-CAM5 model distinct setups: (1) FireOn, which smoke emissions any resulting smoke–cloud–radiation interactions included; (2) FireOff, no (3) RadOff, microphysical included but does not interact directly radiation. Over course trajectory, differences free tropospheric thermodynamic properties FireOn FireOff nearly identical those showing aerosol–radiation primarily responsible for These non-intuitive: addition expected heating within core plume, there also “banding” effect cooler temperature (∼1–2 K) greatly enhanced moisture (>2 g kg−1) at plume top. This banding caused by vertical displacement former continental troposphere anomalous diabatic due absorption sunlight manifests as few hundred meters per day reduction large-scale subsidence over ocean. A (LES) then forced fields taken outputs runs. Cases run selectively perturbing one variable (e.g., number concentration, temperature, moisture, velocity) time better understand contributions different indirect (microphysical), “large-scale” semi-direct (above-cloud changes), “local” (below-cloud absorption) Despite more than 5-fold increase cloud droplet concentration when including concentrations, minimal fraction evolution LES comparing base perturbed dynamic forcings. factor 2 decrease background concentrations shifts classical entrainment-driven “deepening–warming” trade precipitation-driven “drizzle-depletion” open cells, however. changes WRF-simulated adjustments strongly influence terms both rate deepening (especially inversion jump subsidence) final effect). Such would have been possible simulate using small-domain alone.

Язык: Английский

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Factors affecting precipitation formation and precipitation susceptibility of marine stratocumulus with variable above- and below-cloud aerosol concentrations over the Southeast Atlantic

Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(4), С. 2769 - 2793

Опубликована: Март 2, 2022

Abstract. Aerosol–cloud–precipitation interactions (ACIs) provide the greatest source of uncertainties in predicting changes Earth's energy budget due to poor representation marine stratocumulus and associated ACIs climate models. Using situ data from 329 cloud profiles across 24 research flights NASA ObseRvations Aerosols above CLouds their intEractionS (ORACLES) field campaign September 2016, August 2017, October 2018, it is shown that contact between above-cloud biomass burning aerosols over Southeast Atlantic Ocean was with precipitation suppression a decrease susceptibility (So) aerosols. The 173 “contact” aerosol concentration (Na) greater than 500 cm−3 within 100 m tops had 50 % lower rate (Rp) 20 So, on average, compared 156 “separated” Na less up at least tops. Contact separated statistically significant differences droplet (Nc) effective radius (Re) (95 confidence intervals two-sample t test are reported). 84 90 higher Nc 1.4 1.6 µm Re profiles. In clean boundary layers (below-cloud 350 cm−3), 25 31 0.2 0.5 Re. polluted exceeding 98 108 1.8 On other hand, insignificant average liquid water path, thickness, meteorological parameters like surface temperature, tropospheric stability, estimated inversion strength. These results suggest microphysical properties were driven by rather effects, adjustments existing relationships Rp model parameterizations should be considered account for role ACIs.

Язык: Английский

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Dust-planetary boundary layer interactions amplified by entrainment and advections

Atmospheric Research, Год журнала: 2022, Номер 278, С. 106359 - 106359

Опубликована: Июль 25, 2022

Mineral dust contributes to more than half of the global aerosol loading. However, radiative impacts aerosols on planetary boundary layer (PBL) structure have not been explored sufficiently. During a typical storm event over Tarim Basin, exhibit well-mixed distribution during daytime in spite shallow particles accumulated at higher altitudes. By contrast, nocturnal plumes are located near surface due stable stratification. We demonstrate that these differentiated vertical distributions determine spatial heterogeneity loading, fluxes and PBL height variations. Dust cause suppression nighttime promotion through modulating atmospheric budgets. Specifically, dust-induced cooling effect within directly inhibits development. is then amplified by entrainment processes resulting excessively low height, especially for below but top. weaken updrafts from downdrafts free atmosphere, which further reduce mixing attenuating horizontal advection, eventually amplify suppression. At night, near-surface stimulate warm unstable lower generate advection heating promote Our study highlights importance specifying parameters activities quantifying dust-PBL interactions.

Язык: Английский

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A meteorological overview of the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign over the southeastern Atlantic during 2016–2018: Part 2 – Daily and synoptic characteristics

Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(21), С. 14209 - 14241

Опубликована: Ноя. 8, 2022

Abstract. Part 1 (Ryoo et al., 2021) provided a climatological overview of the ObsErvation Aerosols above CLouds and their intEractionS (ORACLES) period assessed representativeness deployment years. In part 2, more detailed meteorological analyses support interpretation airborne measurements for aerosol transport its interaction with low clouds over southeastern (SE) Atlantic Ocean during September 2016, August 2017, October 2018 deployments at daily synoptic scale. The key characteristics 2016 are (1) southern African easterly jet (AEJ-S), centered around 600 hPa (∼4 km), which strengthens throughout month in concert warming continental heat low, strongest winds occurring 23 September. These advect both moisture free troposphere. (2) Mid-tropospheric black carbon (BC) is entrained times into boundary layer, (3) convection land dry south about 10∘ S moist north S. mean low-cloud fraction (low CF) well correlated high tropospheric stability (LTS, r=0.44–0.73 flight domain; 0–10∘ E, 5–25∘ S) moderately layer height (BLH, r=0.37–0.52), defined as altitude maximum vertical gradient moisture. For 2017 deployment, primary that AEJ-S lower (∼3 km; ∼700 hPa) further (5–7∘ than only becomes established by 20 August, separate present aloft 500 (∼5.5 km) before that, mid-tropospheric BC–RH coupling after develops, 3 km, CF less closely LTS (r=0.16–0.57) BLH (r=0.11–0.25) (4) reaches 700 Namibian–Kalahari dryland (∼15–25∘ S, ∼18–24∘ E), generating plume subsequently advected AEJ-S. develops hPa, driven Kalahari (∼10–25∘ ∼12–24∘ but it diminishes time moves southward, offshore advection BC water vapor strongly modulated 8–10∘ early October, this decreases mid-latitude frontal systems develop weakens mid-to-late AEJ-S–low-level (LLJ) coastal Namibian region relationship among all months, largely reduced strong LLJ, especially to cloud deck's south, insignificant compared other 2 partially due variability introduced passage disturbance.

Язык: Английский

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Seasonal variations in fire conditions are important drivers in the trend of aerosol optical properties over the south-eastern Atlantic

Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(13), С. 8767 - 8785

Опубликована: Июль 7, 2022

Abstract. From June to October, southern Africa produces one-third of the global biomass burning (BB) emissions by widespread fires. BB aerosols are transported westward over south-eastern Atlantic with mid-tropospheric winds, resulting in significant radiative effects. Ascension Island (ASI) is located midway between and South America. 2016 October 2017, a 17-month situ observation campaign on ASI found low single-scattering albedo (SSA) as well high mass absorption cross-section black carbon (MACBC), demonstrating strong absorbing marine boundary layer Atlantic. Here we investigate monthly variations critical optical properties aerosols, i.e. SSA MACBC, during seasons driving factors behind these variations. Both MACBC increase from August decrease September October. The average 0.81 at 529 nm wavelength, highest mean ∼ 0.85 lowest 0.78 August. enhancement (Eabs) derived shows similar trends SSA, whole 1.96 2.07 respectively. As Eabs higher than 1.5 commonly adopted value climate models, this result suggests more model simulations. We find enhanced ratio BC CO (ΔBC/ΔCO, equal BC/ΔCO background concentration considered be 0) correlated providing simple way estimate aerosol characteristics exponential function proposed can approximate BC/ΔCO, when small it capture rapid growth decreases. influenced combustion conditions scavenging. analysis location BB, primary source fuel, water content combined cloud cover precipitation transport areas plume, conclude that likely caused becoming flaming. reduction fuels may responsible for change two factors, one being lower proportion flaming conditions, possibly associated surface wind speed area, other an pathway, leading scavenging, which ultimately results MACBC.

Язык: Английский

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An attribution of the low single-scattering albedo of biomass burning aerosol over the southeastern Atlantic

Atmospheric chemistry and physics, Год журнала: 2023, Номер 23(8), С. 4775 - 4799

Опубликована: Апрель 24, 2023

Abstract. Aerosol over the remote southeastern Atlantic is some of most sunlight-absorbing aerosol on planet: in situ free-tropospheric single-scattering albedo at 530 nm wavelength (SSA530 nm) ranges from 0.83 to 0.89 within ORACLES (ObseRvations Aerosols above CLouds and their intEractionS) aircraft flights late August–September. Here we seek explain low SSA. The SSA depends strongly black carbon (BC) number fraction, which 0.15 0.4. Low organic (OA)-to-BC mass ratios 8–14 modified combustion efficiency values >0.975 point indirectly dry, flame-efficient primarily grass fuels, with back trajectories ending miombo woodlands Angola. youngest aerosol, aged 4–5 d since emission, occupied top half a 5 km thick plume sampled directly west Angola vertically consistent BC:ΔCO (carbon monoxide) ratio, indicating homogenization source emissions. younger transported more quickly off continent by stronger winds, overlaid older, slower-moving larger mean particle size fraction BC-containing particles. This ongoing gas condensation coagulation smaller non-BC particles upon volumes OA:BC older were smaller, attributed evaporation following fragmentation, instead dilution or thermodynamics. CLARIFY (CLoud–Aerosol–Radiation Interaction Forcing: Year 2017) campaign aerosols that had traveled further reach Ascension Island. reported higher BC fractions, lower ratios, yet absorption coefficients compared this study's. Values one 2017 flight, held midway Island, are intermediate, confirming long-range changes. Overall data continuing oxidation through fragmentation releasing subsequently enter phase, reducing OA mass, rather than support best fit: SSA530nm=0.801+0055⋅(OA:BC) (r=0.84). fires southern Africa emit approximately one-third world's carbon; emitted distinct other regional smoke emissions, composition needs be represented appropriately realistically depict radiative effects.

Язык: Английский

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