Aerosol transport over the Andes from the Amazon Basin to the remote Pacific Ocean: A multiyear CALIOP assessment

Bourgeois, Quentin; Ekman, Annica M. L.; Krejci, Radovan

doi:10.1002/2015jd023254

Cited by 51 publications

(45 citation statements)

References 69 publications

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“…Although their emission is much smaller than marine and dust aerosols, smoke particles contribute at least 10 % of the FT AOD. This can partly be explained by the location of the emission sources (near the convective regions) and aerosol properties such as hygroscopicity, which is likely lower for smoke than sulfate-containing pollution (e.g., Carrico et al, 2010). Sea salt particles are hydrophilic and efficient cloud condensation nuclei.…”

Section: Daytime Analysismentioning

confidence: 99%

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

et al. 2018

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Abstract. The global aerosol extinction from the CALIOP space lidar was used to compute aerosol optical depth (AOD) over a 9-year period (2007–2015) and partitioned between the boundary layer (BL) and the free troposphere (FT) using BL heights obtained from the ERA-Interim archive. The results show that the vertical distribution of AOD does not follow the diurnal cycle of the BL but remains similar between day and night highlighting the presence of a residual layer during night. The BL and FT contribute 69 and 31 %, respectively, to the global tropospheric AOD during daytime in line with observations obtained in Aire sur l'Adour (France) using the Light Optical Aerosol Counter (LOAC) instrument. The FT AOD contribution is larger in the tropics than at mid-latitudes which indicates that convective transport largely controls the vertical profile of aerosols. Over oceans, the FT AOD contribution is mainly governed by long-range transport of aerosols from emission sources located within neighboring continents. According to the CALIOP aerosol classification, dust and smoke particles are the main aerosol types transported into the FT. Overall, the study shows that the fraction of AOD in the FT – and thus potentially located above low-level clouds – is substantial and deserves more attention when evaluating the radiative effect of aerosols in climate models. More generally, the results have implications for processes determining the overall budgets, sources, sinks and transport of aerosol particles and their description in atmospheric models.

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Section: Daytime Analysismentioning

confidence: 99%

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

et al. 2018

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“…biomass burning injection height, deposition and BL mixing have also been reported as important (Kipling et al, 2016;Peers et al, 2016). In addition, pyro-convection and orographic lifting are two regional processes that can transport aerosols from the surface to the FT (e.g., Fromm et al, 2006;Yumimoto et al, 2009;Bourgeois et al, 2015). Although Veira et al (2015) showed that only a small fraction (4-5%) of biomass burning plumes reaches the FT, Devasthale and Thomas (2011) indicated that smoke plumes are frequently found above clouds over the ocean near intense biomass burning regions.…”

Section: Introductionmentioning

confidence: 99%

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

Bourgeois¹,

Ekman²,

Renard³

et al. 2017

Preprint

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Abstract. The global aerosol extinction from the CALIOP space lidar was used to compute aerosol optical depth (AOD) over a nine-year period (2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) and partitioned between the boundary layer (BL) and the free troposphere (FT) using BL heights obtained from the ERA-Interim archive. The results show that the vertical distribution of AOD does not follow the diurnal cycle of the BL but remains similar between day and night highlighting the presence of a residual layer during night. The BL and FT contribute 69% and 31%, respectively, to the global tropospheric AOD during daytime in line with observations 5 obtained using the Light Optical Aerosol Counter (LOAC) instrument. The FT AOD contribution is larger in the tropics than at mid-latitudes which indicates that convective transport largely controls the vertical profile of aerosols. Over oceans, the FT AOD contribution is mainly governed by long-range transport of aerosols from emission sources located within neighboring continents. According to the CALIOP aerosol classification, dust and smoke particles are the main aerosol types transported into the FT. Overall, the study shows that the fraction of AOD in the FT -and thus potentially located above low-level clouds 10-is substantial and deserves more attention when evaluating the radiative effect of aerosols in climate models. More generally, the results have implications for process determining the overall budgets, sources, sinks and transport of aerosol particles and their description in atmospheric models.

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“…This indicates driving processes are common throughout. The aerosol vertical profile is approximately vertical from the surface to a height of: 2.25 km (Huang et al, 2015; Table 2 therein), ~1.5 km (Bourgeois et al, 2015; Fig. 6 therein), ~2 km (Baars et al, 2012; Fig.…”

Section: Drivers Of the Pollutant Vertical Distributionmentioning

confidence: 98%

“…This is important for understanding how mixing, advection and removal affect pollutants differently. Likewise, recent lidar remote sensing from satellite (Bourgeois et al, 2015;Huang et al, 2015) and surface (Baars et al, 2012) platforms do not provide the comprehensive dataset best suited to examining the drivers of multi-pollutant vertical distribution.…”

Section: Introductionmentioning

confidence: 99%

The vertical distribution of biomass burning pollution over tropical South America from aircraft in situ measurements during SAMBBA

Darbyshire¹,

Morgan²,

Allan³

et al. 2018

Preprint

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Abstract. To reduce the uncertainties in processes driving the vertical distribution of biomass burning pollutants, and thus impacts on regional weather and climate, we present an integrated analysis of vertical profiles of pollutants and meteorological parameters measured on flights during the 2012 South American Biomass Burning Analysis (SAMBBA) field experiment. During the dry season there were significant contrasts in the composition and vertical distribution of haze between western and eastern regions of tropical South America. Owing to an active or residual convective mixing layer, the aerosol burden was similar from the surface to ~&#8201;1.5&#8201;km in the west and ~&#8201;3&#8201;km in the east. Black carbon mass loadings were double in the east (1.7&#8201;&#181;g&#8201;cm&#8722;3) than west (0.85&#8201;&#181;g&#8201;cm&#8722;3) but aerosol scattering coefficients at 550&#8201;nm were similar (~&#8201;120&#8201;Mm&#8722;1), as too were CO surface concentrations (310&#8211;340&#8201;ppb). We attribute these contrasts to the more flaming combustion of Cerrado fires in the east and more smouldering combustion of deforestation and pasture fires in the west. Horizontal wind shear was important in inhibiting mixed layer growth and plume rise, in addition to advecting pollutants from the Cerrado regions into the remote tropical forest of central Amazonia. Optically thin layers above the mixing layer indicates roles for both plume injection and shallow moist convection in delivering pollution to the lower free troposphere. However, detrainment of large smoke plumes into the upper free troposphere was very infrequently observed. Our results reiterate that thermodynamics control the pollutant vertical distribution and thus point to the need for correct model representation so the spatial distribution and vertical structure of biomass burning smoke is captured. Our observations of relatively large concentrations of aerosol aloft and of CO near surface suggest that there is a greater contribution of pollutants from more complete combustion with altitude. Release of appropriate emissions from the initial more flaming and later residual smouldering phases of a fire at appropriate altitudes may be especially important to ensure models can accurately predict aerosol-radiation, aerosol-cloud and air quality impacts.

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Aerosol transport over the Andes from the Amazon Basin to the remote Pacific Ocean: A multiyear CALIOP assessment

Cited by 51 publications

References 69 publications

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

The vertical distribution of biomass burning pollution over tropical South America from aircraft in situ measurements during SAMBBA

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