Variability of Absorption and Optical Properties of Key Aerosol Types Observed in Worldwide Locations

Dubovik, Оleg; Holben, B. N.; Eck, T. F.; Смирнов, А. И.; Kaufman, Yoram J.; King, Michael D.; Tanré, D.; Slutsker, I.

doi:10.1175/1520-0469(2002)059<0590:voaaop>2.0.co;2

Cited by 2,824 publications

(3,537 citation statements)

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“…4b. The BrC contribution (associated with high å abs ) is more important at the end of the dry season and is lower during August, when the aerosol particles likely arrive from Zambian woodland savanna fires (Barbosa et al, 1999), which burn more efficiently and emit aerosol particles with lower ω 0 , 0.84 ± 0.015 at 670 nm in average (Dubovik et al, 2002). Additionally, on average, high σ ap 637 events (see increasing circle size in Fig.…”

Section: Variability Of Optical Properties During the Dry Seasonmentioning

confidence: 94%

“…Agricultural clearing fires, like savanna fires, are dominated by the flaming combustion phase, in contrast to deforestation fires, where less than 50 % of the biomass is burned in the flaming phase (Dubovik et al, 2002). An important part of forest fires occurs in the form of smoldering combustion due to higher fuel moisture (Guyon et al, 2005 other hand, flaming fires, which produce abundant BC aerosol particles, tend to exhibit lower ω 0 and higher ER BC (Akagi et al, 2011).…”

Section: Bc To Co Enhancement Ratiomentioning

confidence: 99%

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Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Saturno¹,

Holanda²,

Pöhlker³

et al. 2017

Preprint

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Abstract. The Amazon rain forest is considered a very sensitive ecosystem that could be significantly affected by a changing climate. It is still one of the few places on Earth where the atmosphere in the continent approaches near-pristine conditions for some periods of the year. The Amazon Tall Tower Observatory (ATTO) has been built in central Amazonia to monitor the atmospheric and forest ecosystem conditions. The atmospheric conditions at the ATTO site oscillate between biogenic and biomass burning (BB) dominated states. By using a comprehensive ground-based aerosol measurement setup, we studied the physical and chemical properties of aerosol particles at the ATTO site. This parameterization of å abs as a function of the BC to OA mass ratio was investigated and was found applicable to tropical forest emissions but further investigation is required, especially by segregating fuel types. Additionally, important enhancements of the BC mass absorption cross-section (α abs ) were found over the measurement period. This enhancement could be linked to heavy coating of the BC aerosol particles. In the future, the BC mixing state should be systematically investigated by using different instrumental approaches.

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Section: Variability Of Optical Properties During the Dry Seasonmentioning

confidence: 94%

Section: Bc To Co Enhancement Ratiomentioning

confidence: 99%

Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Saturno¹,

Holanda²,

Pöhlker³

et al. 2017

Preprint

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“…The Aerosol Robotic Network (AERONET) (Holben et al, 1998) with ∼100 identical globally distributed sun-and sky-scanning ground-based automated radiometers provides measurements of aerosol optical properties throughout the world (Dubovik and King, 2000;Dubovik et al, 2002). In this study, AERONET measured aerosol optical depth (AOD) at 675 nm and 440 nm from six sites over West Africa are used to derive the AOD at 550 nm (using the Angström exponent) for comparison with model results.…”

Section: Aeronet Surface Observation Networkmentioning

confidence: 99%

Radiative impact of mineral dust on monsoon precipitation variability over West Africa

et al. 2011

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Abstract. The radiative forcing of dust and its impact on precipitation over the West Africa monsoon (WAM) region is simulated using a coupled meteorology and aerosol/chemistry model (WRF-Chem). During the monsoon season, dust is a dominant contributor to aerosol optical depth (AOD) over West Africa. In the control simulation, on 24-h domain average, dust has a cooling effect (−6.11 W m −2 ) at the surface, a warming effect (6.94 W m −2 ) in the atmosphere, and a relatively small TOA forcing (0.83 W m −2 ). Dust modifies the surface energy budget and atmospheric diabatic heating. As a result, atmospheric stability is increased in the daytime and reduced in the nighttime, leading to a reduction of late afternoon precipitation by up to 0.14 mm/h (25%) and an increase of nocturnal and early morning precipitation by up to 0.04 mm/h (45%) over the WAM region. Dust-induced reduction of diurnal precipitation variation improves the simulated diurnal cycle of precipitation when compared to measurements. However, daily precipitation is only changed by a relatively small amount (−0.17 mm/day or −4%). The dust-induced change of WAM precipitation is not sensitive to interannual monsoon variability. On the other hand, sensitivity simulations with weaker to stronger absorbing dust (in order to represent the uncertainty in dust solar absorptivity) show that, at the lower atmosphere, dust longwave warming effect in the nighttime surpasses its shortwave cooling effect in the daytime; this leads to a less stable atmosphere associated with more convective precipitation in the nighttime. As a result, the dust-induced change of daily WAM precipitation varies from a significant reduction of −0.52 mm/day (−12%, weaker absorbing dust) to a small increase of 0.03 mm/day (1%, stronger absorbing dust). This variation originates from the competition between dust impact on daytime and nightCorrespondence to: C. Zhao (chun.zhao@pnl.gov) time precipitation, which depends on dust shortwave absorption. Dust reduces the diurnal variation of precipitation regardless of its absorptivity, but more reduction is associated with stronger absorbing dust.

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“…Aerosol inversion products include aerosol microphysical properties such as particle size distribution, complex refractive index, and phase function (Dubovik and King, 20 2000;Dubovik et al, 2002;. We use inversions from the almucantar mode sky measurements to build a regional smoke aerosol model.…”

Section: Aeronet Sun/sky Aerosol Productsmentioning

confidence: 99%

Characterizing the 2015 Indonesia Fire Event Using Modified MODIS Aerosol Retrievals

Shi¹,

Levy²,

Eck³

et al. 2018

Preprint

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Abstract. The Indonesian fire and smoke event of 2015 was an extreme episode that affected public health and caused severe economic and environmental damage. The MODIS Dark Target (DT) aerosol algorithm, developed for global applications, significantly underestimated regional aerosol optical depth (AOD) during this episode. The larger-than-globalaveraged uncertainties in DT product over this event were due to both an overly zealous set of masks that mistook heavy smoke plumes for clouds and/or inland water, and also an aerosol model developed for generic global aerosol conditions. 15Using Aerosol Robotic Network (AERONET) Version 3 sky inversions of local AERONET stations, we created a specific aerosol model for the extreme event. Thus, using this new less-absorbing aerosol model, cloud masking based on results of the MODIS cloud optical properties algorithm, and relaxed thresholds on both inland water tests and upper limits of the AOD retrieval we created a research algorithm, and applied it to 80 appropriate MODIS granules during the event.Collocating and comparing with AERONET AOD shows that the research algorithm doubles the number of MODIS 20 retrievals greater than 1.0, while also significantly improving agreement with AERONET. The final results show that the operational DT algorithm had missed approximately 0.22 of the regional mean AOD, but as much as AOD = 3.0 for individual 0.5° grid boxes. This amount of missing AOD can skew the perception of the severity of the event, affect estimates of regional aerosol forcing, and alter aerosol modeling and forecasting that assimilate MODIS aerosol data products. These results will influence the future development of the global DT aerosol algorithm. 25

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Variability of Absorption and Optical Properties of Key Aerosol Types Observed in Worldwide Locations

Cited by 2,824 publications

References 93 publications

Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Radiative impact of mineral dust on monsoon precipitation variability over West Africa

Characterizing the 2015 Indonesia Fire Event Using Modified MODIS Aerosol Retrievals

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