scholarly journals Emissions Relationships in Western Forest Fire Plumes: I. Reducing the Effect of Mixing Errors on Emission Factors

2019 ◽  
Author(s):  
Robert B. Chatfield ◽  
Meinrat O. Andreae ◽  
◽  
Keyword(s):  
Forest Fire ◽  
Dry Mass ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Theoretical Description ◽  
Total Carbon ◽  
Fire Plume ◽  
Fire Plumes ◽  
Western Us ◽  
Carbon Mass

Abstract. Studies of emission factors from biomass burning using aircraft data complement the results of lab studies and extend them to conditions of immense hot conflagrations. We illustrate and discuss emission relationships for 422 individual samples from many forest-fire plumes in the Western US. The samples are from two NASA investigations: ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) and SEAC4RS (Studies of Emissions and Atmospher-ic Composition, Clouds, and Climate Coupling by Regional Surveys). This work provides sample-by-sample enhancement ratios (EnRs) for 23 gases and particulate properties. Many EnRs provide candidates for emission ratios (ERs, corresponding to the EnR at the source) when the origin and degree of transformation is understood and appropriate. From these, emission factors (EFs) can be estimated when the fuel dry mass consumed is known or can be estimated using the carbon mass budget approach. This analysis requires understanding the interplay of mixing of the plume with surrounding air. Some initial examples emphasize that measured Ctot = CO2 + CO in a fire plume does not necessarily describe the emissions of the total carbon liberated in the flames, Cburn. Rather, it represents Ctot = Cburn + Cbkgd, which includes possibly varying background concentrations for en-trained air. Consequently, we present a simple theoretical description for plume entrainment for multiple tracers from flame to hundreds of kilometers downwind and illustrate some intrinsic linear behaviors. The analysis suggests a Mixed Effects Regression Emission Technique (MERET), which can eliminate occasional strong biases associated with the commonly used normalized excess mix-ing ratio (NEMR) method. MERET splits Ctot to reveal Cburn by exploiting the fact that Cburn and all tracers respond linearly to dilution, while each tracer has consistent EnR behavior (slope of tracer concentration with respect to Cburn). The two effects are separable. Two or three or preferably more emission indicators are required as a minimum; here we used ten. Limited variations in the EnRs for each tracer can be incorporated and the variations and co-variations analyzed. The percentage CO yield (or the modified combustion efficiency) plays some role. Other co-relationships involving ni-trogen and organic classes are more prominent; these have strong relationships to the Cburn to O3 emission relationship. In summary, MERET allows fine spatial resolution (EnRs for individual ob-servations) and comparison of similar plumes distant in time and space. Alkene ratios provide us with an approximate photochemical timescale. This allows discrimination and definition, by fire sit-uation, of ERs, allowing us to estimate emission factors.

scholarly journals Emissions relationships in western forest fire plumes – Part 1: Reducing the effect of mixing errors on emission factors

2020 ◽  
Vol 13 (12) ◽  
pp. 7069-7096
Author(s):  
Robert B. Chatfield ◽  
Meinrat O. Andreae ◽  
◽  
Keyword(s):  
Forest Fire ◽  
Dry Mass ◽  
Emission Factors ◽  
Theoretical Description ◽  
Total Carbon ◽  
Theoretical Development ◽  
Atmospheric Composition ◽  
Fire Plume ◽  
Fire Plumes ◽  
Carbon Mass

Abstract. Studies of emission factors from biomass burning using aircraft data complement the results of lab studies and extend them to conditions of immense hot conflagrations. A new theoretical development of plume theory for multiple tracers is developed after examining aircraft samples. We illustrate and discuss emissions relationships for 422 individual samples from many forest fire plumes in the Western USA. Samples are from two NASA investigations: ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) and SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys). This work provides sample-by-sample enhancement ratios (EnRs) for 23 gases and particulate properties. Many EnRs provide candidates for emission ratios (ERs, corresponding to the EnR at the source) when the origin and degree of transformation is understood. From these, emission factors (EFs) can be estimated, provided the fuel dry mass consumed is known or can be estimated using the carbon mass budget approach. This analysis requires understanding the interplay of mixing of the plume with surrounding air. Some initial examples emphasize that measured Ctot=CO2+CO in a fire plume does not necessarily describe the emissions of the total carbon liberated in the flames, Cburn. Rather, it represents Ctot=Cburn+Cbkgd, which includes possibly varying background concentrations for entrained air. Consequently, we present a simple theoretical description for plume entrainment for multiple tracers from the flame tops to hundreds of kilometers downwind and illustrate some intrinsic linear behaviors. The analysis suggests a mixed-effects regression emission technique (MERET), which can eliminate occasional strong biases associated with the commonly used normalized excess mixing ratio (NEMR) method. MERET splits Ctot to reveal Cburn by exploiting the fact that Cburn and all tracers respond linearly to dilution, while each tracer has consistent EnR behavior (slope of tracer concentration with respect to Cburn). The two effects are separable. Two or three or preferably more emission indicators are required as a minimum; here we used eight. In summary, MERET allows a fine spatial resolution (EnRs for individual observations) and comparison of similar plumes that are distant in time and space. Alkene ratios provide us with an approximate photochemical timescale. This allows discrimination and definition, by fire situation, of ERs, allowing us to estimate emission factors.

scholarly journals Speciated and total emission factors of particulate organics from burning western US wildland fuels and their dependence on combustion efficiency

2019 ◽  
Vol 19 (2) ◽  
pp. 1013-1026 ◽  
Author(s):  
Coty N. Jen ◽  
Lindsay E. Hatch ◽  
Vanessa Selimovic ◽  
Robert J. Yokelson ◽  
Robert Weber ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Large Scale ◽  
Vacuum Ultraviolet ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Organic Chemical ◽  
Wildfire Smoke ◽  
Western Us ◽  
Fire Conditions

Abstract. Western US wildlands experience frequent and large-scale wildfires which are predicted to increase in the future. As a result, wildfire smoke emissions are expected to play an increasing role in atmospheric chemistry while negatively impacting regional air quality and human health. Understanding the impacts of smoke on the environment is informed by identifying and quantifying the chemical compounds that are emitted during wildfires and by providing empirical relationships that describe how the amount and composition of the emissions change based upon different fire conditions and fuels. This study examined particulate organic compounds emitted from burning common western US wildland fuels at the US Forest Service Fire Science Laboratory. Thousands of intermediate and semi-volatile organic compounds (I/SVOCs) were separated and quantified into fire-integrated emission factors (EFs) using a thermal desorption, two-dimensional gas chromatograph with online derivatization coupled to an electron ionization/vacuum ultraviolet high-resolution time-of-flight mass spectrometer (TD-GC × GC-EI/VUV-HRToFMS). Mass spectra, EFs as a function of modified combustion efficiency (MCE), fuel source, and other defining characteristics for the separated compounds are provided in the accompanying mass spectral library. Results show that EFs for total organic carbon (OC), chemical families of I/SVOCs, and most individual I/SVOCs span 2–5 orders of magnitude, with higher EFs at smoldering conditions (low MCE) than flaming. Logarithmic fits applied to the observations showed that log (EFs) for particulate organic compounds were inversely proportional to MCE. These measurements and relationships provide useful estimates of EFs for OC, elemental carbon (EC), organic chemical families, and individual I/SVOCs as a function of fire conditions.

scholarly journals A subsiding regional forest fire aerosol layer at Whistler, BC: implications for interpretation of mountaintop chemistry observations

2010 ◽  
Vol 10 (8) ◽  
pp. 20303-20327
Author(s):  
I. G. Mc Kendry ◽  
J. Gallagher ◽  
P. Campuzano Jost ◽  
A. Bertram ◽  
K. Strawbridge ◽  
...  
Keyword(s):  
Forest Fire ◽  
Forest Fires ◽  
Aerosol Layer ◽  
Synoptic Scale ◽  
Fire Plume ◽  
Fire Plumes ◽  
Physico Chemical ◽  
Air Chemistry ◽  
Regional Forest ◽  
Remote Sensing Methods

Abstract. On 30 August 2009, intense forest fires in interior BC, together with synoptic scale meteorological subsidence and easterly winds resulted in transport of a broad forest fire plume across southwestern BC. The physico-chemical and optical characteristics of the plume as observed from Saturna island (AERONET), CORALNet-UBC and the Whistler Mountain air chemistry facility were consistent with forest fire plumes that have been observed elsewhere in continental North America. However, the importance of smoke plume subsidence in relation to the interpretation of mountaintop chemistry observations is highlighted on the basis of deployment both a CL31 ceilometer and a single particle mass spectrometer (SPMS) in a mountainous setting. The SPMS was used to identify the biomass plume based on levoglucosan and potassium markers. Data from the SPMS are also used to show that the biomass plume was correlated with nitrate, but not correlated with sulphate or sodium. This study not only provides baseline measurements of biomass burning plume physico-chemical characteristics in western Canada, but also highlights the importance of lidar remote sensing methods in the interpretation of mountaintop chemistry measurements.

scholarly journals The nitrogen budget of laboratory-simulated western US wildfires during the FIREX 2016 Fire Lab study

2020 ◽  
Vol 20 (14) ◽  
pp. 8807-8826
Author(s):  
James M. Roberts ◽  
Chelsea E. Stockwell ◽  
Robert J. Yokelson ◽  
Joost de Gouw ◽  
Yong Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Inorganic Compounds ◽  
Combustion Efficiency ◽  
Study Data ◽  
Total Carbon ◽  
Reactive Nitrogen ◽  
Nitrogen Emissions ◽  
Western Us ◽  
Key Species ◽  
Low Temperature Pyrolysis

Abstract. Reactive nitrogen (Nr, defined as all nitrogen-containing compounds except for N2 and N2O) is one of the most important classes of compounds emitted from wildfire, as Nr impacts both atmospheric oxidation processes and particle formation chemistry. In addition, several Nr compounds can contribute to health impacts from wildfires. Understanding the impacts of wildfire on the atmosphere requires a thorough description of Nr emissions. Total reactive nitrogen was measured by catalytic conversion to NO and detection by NO–O3 chemiluminescence together with individual Nr species during a series of laboratory fires of fuels characteristic of western US wildfires, conducted as part of the FIREX Fire Lab 2016 study. Data from 75 stack fires were analyzed to examine the systematics of nitrogen emissions. The measured Nr ∕ total-carbon ratios averaged 0.37 % for fuels characteristic of western North America, and these gas-phase emissions were compared with fuel and residue N∕C ratios and mass to estimate that a mean (±SD) of 0.68 (±0.14) of fuel nitrogen was emitted as N2 and N2O. The Nr detected as speciated individual compounds included the following: nitric oxide (NO), nitrogen dioxide (NO2), nitrous acid (HONO), isocyanic acid (HNCO), hydrogen cyanide (HCN), ammonia (NH3), and 44 nitrogen-containing volatile organic compounds (NVOCs). The sum of these measured individual Nr compounds averaged 84.8 (±9.8) % relative to the total Nr, and much of the 15.2 % “unaccounted” Nr is expected to be particle-bound species, not included in this analysis. A number of key species, e.g., HNCO, HCN, and HONO, were confirmed not to correlate with only flaming or with only smoldering combustion when using modified combustion efficiency, MCE=CO2/(CO+CO2), as a rough indicator. However, the systematic variations in the abundance of these species relative to other nitrogen-containing species were successfully modeled using positive matrix factorization (PMF). Three distinct factors were found for the emissions from combined coniferous fuels: a combustion factor (Comb-N) (800–1200 ∘C) with emissions of the inorganic compounds NO, NO2, and HONO, and a minor contribution from organic nitro compounds (R-NO2); a high-temperature pyrolysis factor (HT-N) (500–800 ∘C) with emissions of HNCO, HCN, and nitriles; and a low-temperature pyrolysis factor (LT-N) (<500 ∘C) with mostly ammonia and NVOCs. The temperature ranges specified are based on known combustion and pyrolysis chemistry considerations. The mix of emissions in the PMF factors from chaparral fuels (manzanita and chamise) had a slightly different composition: the Comb-N factor was also mostly NO, with small amounts of HNCO, HONO, and NH3; the HT-N factor was dominated by NO2 and had HONO, HCN, and HNCO; and the LT-N factor was mostly NH3 with a slight amount of NO contributing. In both cases, the Comb-N factor correlated best with CO2 emission, while the HT-N factors from coniferous fuels correlated closely with the high-temperature VOC factors recently reported by Sekimoto et al. (2018), and the LT-N had some correspondence to the LT-VOC factors. As a consequence, CO2 is recommended as a marker for combustion Nr emissions, HCN is recommended as a marker for HT-N emissions, and the family NH3 ∕ particle ammonium is recommended as a marker for LT-N emissions.

scholarly journals Ground-based remote sensing of an elevated forest fire aerosol layer at Whistler, BC: implications for interpretation of mountaintop chemistry

2010 ◽  
Vol 10 (23) ◽  
pp. 11921-11930 ◽  
Author(s):  
I. G. McKendry ◽  
J. Gallagher ◽  
P. Campuzano Jost ◽  
A. Bertram ◽  
K. Strawbridge ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Forest Fire ◽  
Forest Fires ◽  
Three Dimensional ◽  
Aerosol Layer ◽  
Fire Plume ◽  
Fire Plumes ◽  
Physico Chemical ◽  
Air Chemistry ◽  
Remote Sensing Methods

Abstract. On 30 August 2009, intense forest fires in interior British Columbia (BC) coupled with winds from the east and northeast resulted in transport of a broad forest fire plume across southwestern BC. The physico-chemical and optical characteristics of the plume as observed from Saturna Island (AERONET), CORALNet-UBC and the Whistler Mountain air chemistry facility were consistent with forest fire plumes that have been observed elsewhere in continental North America. However, the importance of three-dimensional transport in relation to the interpretation of mountaintop chemistry observations is highlighted on the basis of deployment of both a CL31 ceilometer and a single particle mass spectrometer (SPMS) in a mountainous setting. The SPMS is used to identify the biomass plume based on levoglucosan and potassium markers. Data from the SPMS are also used to show that the biomass plume was correlated with nitrate, but not correlated with sulphate or sodium. This study not only provides baseline measurements of biomass burning plume physico-chemical characteristics in western Canada, but also highlights the importance of lidar remote sensing methods in the interpretation of mountaintop chemistry measurements.

scholarly journals Airborne measurements of fire Emission Factors for African biomass burning sampled during the MOYA Campaign

2020 ◽  
Author(s):  
Patrick A. Barker ◽  
Grant Allen ◽  
Thomas Bannan ◽  
Archit Mehra ◽  
Keith N. Bower ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Airborne Measurements ◽  
Atlantic Seaboard ◽  
Trace Gas Emissions ◽  
Fire Plumes ◽  
Carbon Dioxide Co2 ◽  
Continental Outflow ◽  
Modified Combustion Efficiency

Abstract. Airborne sampling of methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and nitrous oxide (N2O) mole fractions was conducted during field campaigns targeting fires over Senegal in February and March 2017, and Uganda in January 2019. The majority of fire plumes sampled were close to, or directly over burning vegetation, with the exception of two longer-range flights over the West African Atlantic seaboard, (100–300 km from source) where the continental outflow of biomass burning emissions from a wider area of West Africa was sampled. Fire Emission Factors (EFs) and modified combustion efficiencies (MCEs) were estimated from the enhancements in measured mole fractions. For the Senegalese fires, mean EFs and corresponding one-standard deviation variabilities, in units of g per kg of dry fuel were 1.8 (± 0.06) for CH4, 1633 (± 56.4) for CO2 and 679 (± 1.6) for CO, with a mean MCE of 0.94 (± 0.005). For the Ugandan fires, mean EFs (in units of g kg−1) were 3.1 (± 0.1) for CH4, 1610 (± 54.9) for CO2 and 78 (± 1.9) for CO, with a mean modified combustion efficiency of 0.93 (± 0.004). A mean N2O EF of 0.08 (± 0.002) g kg−1 is also reported for one flight over Uganda; issues with temperature control of the instrument optical bench prevented N2O EFs from being obtained for other flights over Uganda. This study has provided new datasets of African biomass burning EFs and MCEs for two distinct study regions, in which both have been studied little by aircraft measurement previously. These results highlight the important intracontinental variability of biomass burning trace gas emissions, and can be used to better constrain future biomass burning emission budgets. More generally, these results highlight the importance of regional and fuel-type variability when attempting to spatially scale biomass burning emissions. Further work to constrain EFs at more local scales and for more specific (and quantifiable) fuel types will serve to improve global estimates of biomass burning emissions of climate-relevant gases.

scholarly journals Californian forest fire plumes over Southwestern British Columbia: lidar, sunphotometry, and mountaintop chemistry observations

2011 ◽  
Vol 11 (2) ◽  
pp. 465-477 ◽  
Author(s):  
I. McKendry ◽  
K. Strawbridge ◽  
M. L. Karumudi ◽  
N. O'Neill ◽  
A. M. Macdonald ◽  
...  
Keyword(s):  
British Columbia ◽  
Pacific Northwest ◽  
Forest Fire ◽  
Forest Fires ◽  
Regional Scale ◽  
Fire Plume ◽  
Fire Plumes ◽  
Observatory Data ◽  
The Pacific ◽  
June July

Abstract. Forest fires in Northern California and Oregon were responsible for two significant regional scale aerosol transport events observed in southern British Columbia during summer 2008. A combination of ground based (CORALNet) and satellite (CALIPSO) lidar, sunphotometry and high altitude chemistry observations permitted unprecedented characterization of forest fire plume height and mixing as well as description of optical properties and physicochemistry of the aerosol. In southwestern BC, lidar observations show the smoke to be mixed through a layer extending to 5–6 km a.g.l. where the aerosol was confined by an elevated inversion in both cases. Depolarization ratios for a trans-Pacific dust event (providing a basis for comparison) and the two smoke events were consistent with observations of dust and smoke events elsewhere and permit discrimination of aerosol events in the region. Based on sunphotometry, the Aerosol Optical Thicknesses (AOT) reached maxima of ~0.7 and ~0.4 for the two events respectively. Dubovik-retrieval values of reff, f during both the June/July and August events varied between about 0.13 and 0.15 μm and confirm the dominance of accumulation mode size particles in the forest fire plumes. Both Whistler Peak and Mount Bachelor Observatory data show that smoke events are accompanied by elevated CO and O3 concentrations as well as elevated K+/SO4 ratios. In addition to documenting the meteorology and physic-chemical characteristics of two regional scale biomass burning plumes, this study demonstrates the positive analytical synergies arising from the suite of measurements now in place in the Pacific Northwest, and complemented by satellite borne instruments.

scholarly journals Characterization of Emissions and Residue from Measures to Improve Efficiency of In Situ Oil Burns

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Brian K. Gullett ◽  
Johanna Aurell ◽  
Amara Holder ◽  
Nathan Lamie ◽  
Kemal Arsava ◽  
...  
Keyword(s):  
Mass Loss ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Total Carbon ◽  
Total Petroleum Hydrocarbons ◽  
Oil Consumption ◽  
Aspect Ratios ◽  
Length Width ◽  
Air Nozzle

ABSTRACT NUMBER: 1141223 Simulated in situ oil burning tests were conducted in a 14 m × 2.4 m × 2.4 m tank to characterize variations in boom length/width aspect ratios, the use of injection air, nozzle angle, and presence or absence of waves on combustion efficiency. Tests were done with approximately 35 L of unweathered Alaska North Slope oil within an outdoor, fresh water, 63 m3 tank. The combustion plume was sampled with a crane-suspended instrument system. Emission measurements quantified carbon monoxide, carbon dioxide, particulate matter less than 2.5 μm (PM2.5), and total carbon. Post-burn residue samples were collected with pre-weight oil absorbent to determining oil mass loss and total petroleum hydrocarbons (TPH) in the residue. Plume measurements of modified combustion efficiencies (MCET) ranged from 85% to 93%. Measurement of residual, unburnt oil showed that the oil mass loss ranged from 89% to 99%. A three-fold variation in PM2.5 emission factors was observed from the test conditions where the emission factors decreased with increased MCE. The TPH in the residue were found to decrease with increased oil mass loss percentage. In terms of combustion efficiency and oil consumption, results suggest that the most effective burns were those that have high length to width boom aspect ratios and added injection air.

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