Trans-Pacific transport of Asian dust and CO: accumulation of biomass burning CO in the subtropics and dipole structure of transport

Nam, Junsang; Wang, Y.; Luo, Chao; Chu, D. A.

doi:10.5194/acp-10-3297-2010

Cited by 30 publications

(25 citation statements)

References 52 publications

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“…GEOS-Chem has been used previously to show that Asian emissions can lead to enhanced concentrations of CO, ozone, sulfate, and dust aerosols in North America (Heald et al, 2003;Jaegle et al, 2003;Hudman et al, 2004;Park et al, 2004;Heald et al, 2006;Park et al, 2006;Fairlie et al, 2007;Nam et al, 2009). The model has been applied previously to simulation of the INTEX-B data by Zhang et al (2008), focusing on ozone, and by van Donkelaar et al (2008), focusing on sulfate and organic aerosol.…”

Section: General Descriptionmentioning

confidence: 99%

Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes

et al. 2010

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Abstract. We use a 3-D global chemical transport model (GEOS-Chem) to interpret aircraft observations of nitrate and sulfate partitioning in transpacific dust plumes during the INTEX-B campaign of April-May 2006. The model includes explicit transport of size-resolved mineral dust and its alkalinity, nitrate, and sulfate content. The observations show that particulate nitrate is primarily associated with dust, sulfate is primarily associated with ammonium, and Asian dust remains alkaline across the Pacific. This can be reproduced in the model by using a reactive uptake coefficient for HNO 3 on dust (γ (HNO 3 ) ∼10 −3 ) much lower than commonly assumed in models and possibly reflecting limitation of uptake by dust dissolution. The model overestimates gasphase HNO 3 by a factor of 2-3, typical of previous model studies; we show that this cannot be corrected by uptake on dust. We find that the fraction of aerosol nitrate on dust in the model increases from ∼30% in fresh Asian outflow to 80-90% over the Northeast Pacific, reflecting in part the volatilization of ammonium nitrate and the resulting transfer of nitrate to the dust. Consumption of dust alkalinity by uptake of acid gases in the model is slow relative to the lifetime of dust against deposition, so that dust does not acidify (at least not in the bulk). This limits the potential for dust iron released by acidification to become bio-available upon dust deposition. Observations in INTEX-B show no detectable Correspondence to: T. D. Fairlie (t.d.fairlie@nasa.gov) ozone depletion in Asian dust plumes, consistent with the model. Uptake of HNO 3 by dust, suppressing its recycling to NO x , reduces Asian pollution influence on US surface ozone in the model by 10-15% or up to 1 ppb.

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Section: General Descriptionmentioning

confidence: 99%

Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes

et al. 2010

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“…Validating global models against comparison to such individual events can be challenging because model errors in meteorological fields or emissions location can lead to large spatial displacement of the modeled plume relative to observations (e.g., Nam et al, 2010). The low horizontal and vertical resolution of global models, coupled with numerical diffusion can also lead to difficulties in reproducing plumes observed many thousands of kilometers downwind from source regions (e.g., Lin et al, 2010;Rastigejev et al, 2010;Real et al, 2010l;TF-HTAP, 2010).…”

Section: Y Luan and L Jaeglé: Composite Study Of Aerosol Export Eventsmentioning

confidence: 99%

Composite study of aerosol export events from East Asia and North America

Luan

Jaeglé

2013

Atmos. Chem. Phys.

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Abstract.We use satellite observations of aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectrometer (MODIS) together with the GEOS-Chem global chemical transport model to contrast export of aerosols from East Asia and North America during 2004-2010. The GEOSChem model reproduces the spatial distribution and temporal variations of Asian aerosol outflow generally well, although a low bias (−30 %) is found in the model fine mode AOD, particularly during summer. We use the model to identify 244 aerosol pollution export events from E. Asia and 251 export events from N. America over our 7-year study period. When these events are composited by season, we find that the AOD in the outflow is enhanced by 50-100 % relative to seasonal mean values. The composite Asian plume splits into one branch going poleward to the Arctic in 3-4 days, with the other crossing the Pacific Ocean in 6-8 days. A fraction of the aerosols is trapped in the subtropical Pacific High during spring and summer. The N. American plume travels to the northeast Atlantic, reaching Europe after 4-5 days. Part of the composite plume turns anticyclonically in the Azores High, where it slowly decays. Both the Asian and N. American export events are favored by a dipole structure in sea-level pressure anomalies, associated with midlatitude cyclone activity over the respective source regions. This dipole structure during outflow events is a strong feature for all seasons except summer, when convection becomes more important. The observed AOD in the E. Asian outflow exhibits stronger seasonality, with a spring maximum, than the N. American outflow, with a broad spring/summer maximum. The large spring AOD in the Asian outflow is the result of enhanced sulfate and dust aerosol concentrations, but is also due to a larger export efficiency of sulfate and SO 2 from the Asian boundary layer relative to the N. American boundary layer. While the N. American sulfate outflow is mostly found in the lower troposphere (1-3 km altitude), the Asian sulfate outflow occurs at higher altitudes (2-6 km). In the Asian outflow 42-59 % of the sulfate column is present above 2 km altitude, with only 24-35 % in the N. American outflow. We link this to the factor of 2-5 lower precipitation in the warm conveyor belts (WCB) of midlatitude cyclones over E. Asia compared to N. America. This relative lack of precipitation makes Asian WCB very efficient for injecting aerosols in the middle troposphere.

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“…In addition, new long-range transport mechanisms of BB emissions (e.g., the mountain leeside trough) in Southeast Asia have been discovered (Lin et al, 2009). The pollutants from BB can persist for 2 months and cause an enhancement in the following months in the subtropical Pacific (Nam et al 2010). The significant longrange transport of BB emissions likely offsets the policydriven reductions of domestic anthropogenic emissions in South China, where the central government is necessitating a 10%-20% decrease in annual PM 2.5 by 2017 compared with the 2013 levels.…”

Section: Introductionmentioning

confidence: 99%

Regional Impact of Biomass Burning in Southeast Asia on Atmospheric Aerosols during the 2013 Seven South-East Asian Studies Project

Zhang

Wang

et al. 2017

Aerosol Air Qual. Res.

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A nested air quality prediction modeling system (NAQPMS) with an online tracer-tagged module was utilized to investigate the regional impact of biomass burning (BB) on aerosols and source-receptor relationships in Southeast Asia during March-April 2013. NAQPMS could reproduce the three-dimensional spatial distribution of aerosols. Both monthly and episodic analyses indicated that BB significantly contributed to surface and column aerosol concentrations in Southeast Asia along two long-range transport pathways. In the first pathway, aerosols from BB were blown northward from the Indochina peninsula to southwestern provinces in China. The mean contributions of BB decreased from 70%-80% in the source regions to 10%-40% in southwestern China. Myanmar was the largest exporter. In the second pathway, PM 2.5 emitted by BB was uplifted into the mid-altitudes (2000 m) in the Indochina peninsula and transported eastward to the western Pacific at altitudes of 2500-4000 m, passing the South China Sea, southern China and western Pacific. In downwind regions, BB contributed 30%-60% of aerosols at altitudes of 2000-4000 m and 10%-30% below 2000 m. A simple estimation based on source-receptor relationships showed that BB emissions were likely overestimated by 35%-50% in the Fire Inventory from National Center for Atmospheric Research (v1.5).

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Trans-Pacific transport of Asian dust and CO: accumulation of biomass burning CO in the subtropics and dipole structure of transport

Cited by 30 publications

References 52 publications

Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes

Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes

Composite study of aerosol export events from East Asia and North America

Regional Impact of Biomass Burning in Southeast Asia on Atmospheric Aerosols during the 2013 Seven South-East Asian Studies Project

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