A case study of aerosol scavenging in a biomass burning plume over eastern Canada during the 2011 BORTAS field experiment

Franklin, Jonathan; Drummond, J. R.; Griffin, Debora; Pierce, Jeffrey R.; Waugh, D.; Palmer, Paul I.; Parrington, Mark; Lee, James; Lewis, Alastair C.; Rickard, Andrew R.; Taylor, Jonathan; Allan, J. D.; Coe, Hugh; Walker, Kaley A.; Chisholm, L.; Duck, Thomas J.; Hopper, J. T.; Blanchard, Yann; Gibson, Mark; Curry, K. R.; Sakamoto, K. M.; Lesins, Glen; Lin, Dan; Kliever, J.; Saha, A.

doi:10.5194/acp-14-8449-2014

Cited by 23 publications

(23 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7a, with several highaltitude (∼ 7 km) samples having fairly low excess organic aerosol, but significant CO (300 ppbv). This trend is featured in Franklin et al (2014) where the high-altitude plume showed evidence of an aerosol rainout event causing low OA / CO ratios within the plume transected at those high altitudes.…”

Section: Net Production/loss Of Organic Aerosol With Timementioning

confidence: 93%

“…This ensured highgas, low-aerosol sampling periods were not included in the size-distribution analysis. At least one case of this situation in BORTAS-B has been attributed by Franklin et al (2014) to aerosol rainout during transport. The mean background concentrations for both BC number and OA mass were minimal (< 20 cm −3 and 2 µg m −3 , respectively).…”

Section: Plume Criteriamentioning

confidence: 99%

See 1 more Smart Citation

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

et al. 2015

Self Cite

View full text Add to dashboard Cite

Abstract. Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number-size distributions in climate model inventories lead to uncertainties in the CCN (cloud condensation nuclei) concentrations and forcing estimates derived from these models.The BORTAS-B (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellite) measurement campaign was designed to sample boreal biomass-burning outflow over eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size distribution of aged biomass-burning emissions (aged ∼ 1-2 days) from boreal wildfires in northwestern Ontario. The composite median size distribution yields a single dominant accumulation mode with D pm = 230 nm (numbermedian diameter) and σ = 1.5, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios ( OA / CO) along the path of Flight b622 show values of 0.09-0.17 µg m −3 ppbv −1 (parts per billion by volume) with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA (organic aerosol) production/evaporation within the aged plume over the sampling period (plume age: 1-2 days), though it does not preclude OA production/loss at earlier stages. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the OA / CO enhancement ratios. We estimate that the young-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8 (the ranges are due to uncertainty in the entrainment rate). Thus, the size of the freshly emitted particles is relatively unconstrained due to the uncertainties in the plume dilution rates.

show abstract

Section: Net Production/loss Of Organic Aerosol With Timementioning

confidence: 93%

Section: Plume Criteriamentioning

confidence: 99%

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…During the IPY (International Polar Year) in 2008, different Lagrangian studies (e.g., Roiger et al, 2011;Sodemann et al, 2011;Matsui et al, 2011) identified several Asian pollution plumes transported to the Arctic after a strong uplift in WCBs located over the Russian east coast and subsequently transported to the Arctic. Franklin et al (2014) and Taylor et al (2014) have documented the impact of wet removal in Canadian biomass burning plumes and confirmed that wet deposition is the dominant mechanism for BC removal from the atmosphere and consequently determining its lifetime and atmospheric burden and affecting vertical profiles of number and mass concentration.…”

mentioning

confidence: 92%

Cross-polar transport and scavenging of Siberian aerosols containing black carbon during the 2012 ACCESS summer campaign

et al. 2017

View full text Add to dashboard Cite

Abstract. During the ACCESS airborne campaign in July 2012, extensive boreal forest fires resulted in significant aerosol transport to the Arctic. A 10-day episode combining intense biomass burning over Siberia and low-pressure systems over the Arctic Ocean resulted in efficient transport of plumes containing black carbon (BC) towards the Arctic, mostly in the upper troposphere (6-8 km). A combination of in situ observations (DLR Falcon aircraft), satellite analysis and WRF-Chem simulations is used to understand the vertical and horizontal transport mechanisms of BC with a focus on the role of wet removal. Between the northwestern Norwegian coast and the Svalbard archipelago, the Falcon aircraft sampled plumes with enhanced CO concentrations up to 200 ppbv and BC mixing ratios up to 25 ng kg −1 . During transport to the Arctic region, a large fraction of BC particles are scavenged by two wet deposition processes, namely wet removal by large-scale precipitation and removal in wet convective updrafts, with both processes contributing almost equally to the total accumulated deposition of BC. Our results underline that applying a finer horizontal resolution (40 instead of 100 km) improves the model performance, as it significantly reduces the overestimation of BC levels observed at a coarser resolution in the mid-troposphere. According to the simulations at 40 km, the transport efficiency of BC (TE BC ) in biomass burning plumes was larger (60 %), because it was impacted by small accumulated precipitation along trajectory (1 mm). In contrast TE BC was small (< 30 %) and accumulated precipitation amounts were larger (5-10 mm) in plumes influenced by urban anthropogenic sources and flaring activities in northern Russia, resulting in transport to lower altitudes. TE BC due to large-scale precipitation is responsible for a sharp meridional gradient in the distribution of BC concentrations. Wet removal in cumulus clouds is the cause of modeled vertical gradient of TE BC , especially in the mid-latitudes, reflecting the distribution of convective precipitation, but is dominated in the Arctic region by the large-scale wet removal associated with the formation of stratocumulus clouds in the planetary boundary layer (PBL) that produce frequent drizzle.

show abstract

“…Figure 7 shows an example ofĀ on 20 July 2011, which is used as a case study in other BORTAS studies (e.g. Griffin et al, 2013;Franklin et al, 2014). Figure 7a shows longitudinal and latitudinal cross-section views of emissions as they are transported from the Thunder Bay region (50 • N, 88 • W).…”

Section: Tagged Co Model Outputmentioning

confidence: 99%

“…Figure 7a shows longitudinal and latitudinal cross-section views of emissions as they are transported from the Thunder Bay region (50 • N, 88 • W). By the time the plume is observed on 20 July by ground-based observatories over Toronto (43.70 • N, 69.40 • W) (Griffin et al, 2013) and Halifax (44.6 • N, 63.59 • W) (Franklin et al, 2014) the plume is approximately 5-7 days old, corresponding to an emission on 14-15 July. Figure 7b shows that the transported air, intercepted at 63 • W, is composed of a young plume (4-5 days old) surrounded by older air (7 days old) over 47-55 • N. Previous BORTAS-B studies have used the NOAA HYbrid Single-Particle Lagrangian Integrated Trajectory (HYS-PLIT) model (Draxler and Hess, 1998), driven by meteorological reanalyses data from the National Center for Environmental Prediction (NCEP) Global Data Assimilation Program (GDAS) to interpret ground-based remote-sensing data collected during BORTAS-B (Griffin et al, 2013;Franklin et al, 2014).…”

Section: Tagged Co Model Outputmentioning

confidence: 99%

Origin, variability and age of biomass burning plumes intercepted during BORTAS-B

2014

Self Cite

View full text Add to dashboard Cite

Abstract.We use the GEOS-Chem atmospheric chemistry transport model to interpret aircraft measurements of carbon monoxide (CO) in biomass burning outflow taken during the 2011 BORTAS-B campaign over eastern Canada. The model has some skill reproducing the observed variability, with a Spearman's rank correlation r s = 0.65, but has a positive negative bias for observations <100 ppb and a negative bias for observations > 300 ppb. We find that observed CO variations are largely due to fires over Ontario, as expected, with smaller and less variable contributions from fossil fuel combustion from eastern Asia and NE North America. To help interpret observed variations of CO we develop a Eulerian effective physical age of emissions (Ā) metric, accounting for mixing and chemical decay, which we apply to pyrogenic emissions of CO. We find that during BORTAS-B the age of emissions intercepted over Halifax, Nova Scotia is typically 4-11 days, and on occasion as young as two days. We show thatĀ is typically 1-5 days older than the associated photochemical ages inferred from co-located measurements of different hydrocarbons. We find that the frequency distribution of differences between the age measures ( τ ) in plumes (defined by CH 3 CN > 150 ppt) peaks at 3 days. This corresponds to a chemical retardation of 50 %. We find a strong relationship in biomass burning plumes betweenĀ and τ (r 2 = 0.80), which is not present outwith these plumes (r 2 = 0.28). We argue that these observed relationships, together with a robust observed relationship between CO and black carbon aerosol during BORTAS-B (r 2 > 0.7), form the basis of indirect evidence that aerosols co-emitted with gases during pyrolysis markedly slowed down the plume photochemistry during BORTAS-B with respect to photochemistry at the same latitude and altitude in clear skies.

show abstract

A case study of aerosol scavenging in a biomass burning plume over eastern Canada during the 2011 BORTAS field experiment

Cited by 23 publications

References 36 publications

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

Cross-polar transport and scavenging of Siberian aerosols containing black carbon during the 2012 ACCESS summer campaign

Origin, variability and age of biomass burning plumes intercepted during BORTAS-B

Contact Info

Product

Resources

About