Carbon Dioxide in the Free Troposphere and Boundary Layer at the Mt. Bachelor Observatory

McClure, Crystal D.; Jaffe, Daniel A.; Gao, Haixiao

doi:10.4209/aaqr.2015.05.0323

Cited by 28 publications

(15 citation statements)

References 61 publications

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“…The average water vapor for all categories is relatively high, which is indicative of boundary layer transport. This is common for midday at MBO (McClure et al, ).…”

Section: Resultsmentioning

confidence: 91%

Impact of Biomass Burning Plumes on Photolysis Rates and Ozone Formation at the Mount Bachelor Observatory

et al. 2018

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In this paper, we examine biomass burning (BB) events at the Mt. Bachelor Observatory (MBO) during the summer of 2015. We explored the photochemical environment in these BB plumes, which remains poorly understood. Because we are interested in understanding the effect of aerosols only (as opposed to the combined effect of aerosols and clouds), we carefully selected three cloud‐free days in August and investigate the photochemistry in these plumes. At local midday (solar zenith angle (SZA) = 35°), j(NO2) values were slightly higher (0.2–1.8%) in the smoky days compared to the smoke‐free day, presumably due to enhanced scattering by the smoke aerosols. At higher SZA (70°), BB aerosols decrease j(NO2) by 14–21%. We also observe a greater decrease in the actinic flux at 310–350 nm, compared to 360–420 nm, presumably due to absorption in the UV by brown carbon. We compare our measurements with results from the Tropospheric Ultraviolet‐Visible v.5.2 model. As expected, we find a good agreement (to within 6%) during cloud‐free conditions. Finally, we use the extended Leighton relationship and a photochemical model (Aerosol Simulation Program v.2.1) to estimate midday HO2 and RO2 concentrations and ozone production rates (P(O3)) in the fire plumes. We observe that Leighton‐derived HO2 and RO2 values (49–185 pptv) and instantaneous P(O3) (2.0–3.6 ppbv/h) are higher than the results from the photochemical model.

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“…The average water vapor for all categories is relatively high, which is indicative of boundary layer transport. This is common for midday at MBO (McClure et al, ).…”

Section: Resultsmentioning

confidence: 91%

Impact of Biomass Burning Plumes on Photolysis Rates and Ozone Formation at the Mount Bachelor Observatory

et al. 2018

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“…The reference species Y has most commonly been carbon monoxide (CO) or carbon dioxide (CO 2 ), which are thought of as conserved, inert products of combustion (Andreae and Merlet, 2001;Hobbs et al, 2003). McClure et al (2016) showed that this is not always the case for CO 2 . Vegetation uptake can deplete CO 2 in WF plumes within the boundary layer, distorting the NER.…”

Section: Introductionmentioning

confidence: 99%

Can d;PM2.5/d;CO and d;NOy/d;CO Enhancement Ratios Be Used to Characterize the Influence of Wildfire Smoke in Urban Areas?

Laing

Jaffe

Slavens

et al. 2017

Aerosol Air Qual. Res.

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In this study we investigate the use of ΔPM 2.5 /ΔCO and ΔNO y /ΔCO normalized enhancement ratios (NERs) in identifying wildfire (WF) smoke events in urban areas. Nine urban ambient monitoring sites with adequate CO, PM 2.5 , and/or NO y measurements were selected for this study. We investigated if WF events could be distinguished from general urban emissions by comparing NERs for wildfires with NERs calculated using yearly ambient data, which we call the ambient enhancement ratios (AERs). The PM 2.5 /CO and NO y /CO AERs represent typical urban concentrations and can provide insight into the dominant emission sources of the city. All 25 WF events were distinguished because they had ΔPM 2.5 /ΔCO NERs that were significantly greater than the PM 2.5 /CO AER for each site. The ΔPM 2.5 /ΔCO NERs for the WF events ranged from 0.057-0.228 µg m -3 ppbv -1 . In contrast, we were only able to calculate useful ΔNO y /ΔCO NERs (correlations with R 2 > 0.65) for 4 of 17 events (only 17 of 25 events had NO y data). For these 4 events, ΔNO y /ΔCO NERs ranged from 0.044-0.075 ppbv ppbv -1 , not all of which were significantly different from the NO y /CO AERs at the site. We conclude that ΔPM 2.5 /ΔCO NERs are a very useful tool for identifying WF events, but that the high and variable NO y concentrations in urban areas present problems when trying to use ΔNO y /ΔCO NERs.

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“…Bachelor Observatory (MBO) is located on a mountain top in central Oregon at 2.76 km above sea level. The observatory has been in operation for the last decade and has been previously used to study long-range transport and wildfire plumes (e.g., Jaffe et al, 2005;Fischer et al, 2011;Wigder et al, 2013;Baylon et al, 2015;McClure et al, 2016). In this study, we analyze wildfire plumes aged 1-2 days that were observed at MBO in 2012 and 2013.…”

Section: Introductionmentioning

confidence: 99%

Particulate Matter, Ozone, and Nitrogen Species in Aged Wildfire Plumes Observed at the Mount Bachelor Observatory

Briggs

Jaffe

Gao

et al. 2016

Aerosol Air Qual. Res.

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During the summer of 2012 and 2013, we measured carbon monoxide (CO), carbon dioxide (CO 2 ), ozone (O 3 ), nitrogen oxides (NO x ), reactive nitrogen (NO y ), peroxyacetyl nitrate (PAN), aerosol scattering (σ sp ) and absorption, elemental and organic carbon (EC and OC), and aerosol chemistry at the Mount Bachelor Observatory (2.8 km above sea level, Oregon, US). Here we analyze 23 of the individual plumes from regional wildfires to better understand production and loss of aerosols and gaseous species. We also developed a new method to calculate enhancement ratios and Modified Combustion Efficiency (MCE), which takes into account possible changes in background concentrations during transport. We compared this new method to existing methods for calculating enhancement ratios. The MCE values ranged from 0.79-0.98, ΔO 3 /ΔCO ranged from 0.01-0.07 ppbv ppbv -1 , Δσ sp /ΔCO ranged from 0.23-1.32 Mm -1 (at STP) ppbv -1 , ΔNO y /ΔCO ranged from 2.89-12.82 pptv ppbv -1 , and ΔPAN/ΔCO ranged from 1.46-6.25 pptv ppbv -1 . A comparison of three different methods to calculate enhancement ratios (ER) showed that the methods generally resulted in similar Δσ sp /ΔCO, ΔNO y /ΔCO, and ΔPAN/ΔCO; however, there was a significant bias between the methods when calculating ΔO 3 /ΔCO due to the small absolute enhancement of O 3 in the plumes. The ΔO 3 /ΔCO ERs calculated using two common methods were biased low (~20-30%) when compared to the new proposed method. Two pieces of evidence suggest moderate secondary particulate formation in many of the plumes studied: 1) mean observed ΔOC/ΔCO 2 was 0.028 g particulate-C gC -1 (as CO 2 )-27% higher than the midpoint of the biomass burning emission ratio range reported by a recent review-and 2) single scattering albedo (ω) was relatively constant at all MCE values, in contrast with results for fresh plumes. The observed NO x , PAN, and aerosol nitrate represented 6-48%, 25-57%, and 20-69% of the observed NO y in the aged plumes, respectively, and other species represented on average 11% of the observed NO y .

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Carbon Dioxide in the Free Troposphere and Boundary Layer at the Mt. Bachelor Observatory

Cited by 28 publications

References 61 publications

Impact of Biomass Burning Plumes on Photolysis Rates and Ozone Formation at the Mount Bachelor Observatory

Impact of Biomass Burning Plumes on Photolysis Rates and Ozone Formation at the Mount Bachelor Observatory

Can d;PM2.5/d;CO and d;NOy/d;CO Enhancement Ratios Be Used to Characterize the Influence of Wildfire Smoke in Urban Areas?

Particulate Matter, Ozone, and Nitrogen Species in Aged Wildfire Plumes Observed at the Mount Bachelor Observatory

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