279 results on '"Weinheimer, Andrew J."'
Search Results
102. In situ measurements and modeling of reactive trace gases in a small biomass burning plume
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Müller, Markus, primary, Anderson, Bruce E., additional, Beyersdorf, Andreas J., additional, Crawford, James H., additional, Diskin, Glenn S., additional, Eichler, Philipp, additional, Fried, Alan, additional, Keutsch, Frank N., additional, Mikoviny, Tomas, additional, Thornhill, Kenneth L., additional, Walega, James G., additional, Weinheimer, Andrew J., additional, Yang, Melissa, additional, Yokelson, Robert J., additional, and Wisthaler, Armin, additional
- Published
- 2016
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103. Large vertical gradient of reactive nitrogen oxides in the boundary layer: Modeling analysis of DISCOVER‐AQ 2011 observations
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Zhang, Yuzhong, primary, Wang, Yuhang, additional, Chen, Gao, additional, Smeltzer, Charles, additional, Crawford, James, additional, Olson, Jennifer, additional, Szykman, James, additional, Weinheimer, Andrew J., additional, Knapp, David J., additional, Montzka, Denise D., additional, Wisthaler, Armin, additional, Mikoviny, Tomas, additional, Fried, Alan, additional, and Diskin, Glenn, additional
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- 2016
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104. A pervasive role for biomass burning in tropical high ozone/low water structures
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Anderson, Daniel C., primary, Nicely, Julie M., additional, Salawitch, Ross J., additional, Canty, Timothy P., additional, Dickerson, Russell R., additional, Hanisco, Thomas F., additional, Wolfe, Glenn M., additional, Apel, Eric C., additional, Atlas, Elliot, additional, Bannan, Thomas, additional, Bauguitte, Stephane, additional, Blake, Nicola J., additional, Bresch, James F., additional, Campos, Teresa L., additional, Carpenter, Lucy J., additional, Cohen, Mark D., additional, Evans, Mathew, additional, Fernandez, Rafael P., additional, Kahn, Brian H., additional, Kinnison, Douglas E., additional, Hall, Samuel R., additional, Harris, Neil R.P., additional, Hornbrook, Rebecca S., additional, Lamarque, Jean-Francois, additional, Le Breton, Michael, additional, Lee, James D., additional, Percival, Carl, additional, Pfister, Leonhard, additional, Pierce, R. Bradley, additional, Riemer, Daniel D., additional, Saiz-Lopez, Alfonso, additional, Stunder, Barbara J.B., additional, Thompson, Anne M., additional, Ullmann, Kirk, additional, Vaughan, Adam, additional, and Weinheimer, Andrew J., additional
- Published
- 2016
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105. Constraints from observations and modeling on atmosphere–surface exchange of mercury in eastern North America
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Song, Shaojie, primary, Selin, Noelle E., additional, Gratz, Lynne E., additional, Ambrose, Jesse L., additional, Jaffe, Daniel A., additional, Shah, Viral, additional, Jaeglé, Lyatt, additional, Giang, Amanda, additional, Yuan, Bin, additional, Kaser, Lisa, additional, Apel, Eric C., additional, Hornbrook, Rebecca S., additional, Blake, Nicola J., additional, Weinheimer, Andrew J., additional, Mauldin III, Roy L., additional, Cantrell, Christopher A., additional, Castro, Mark S., additional, Conley, Gary, additional, Holsen, Thomas M., additional, Luke, Winston T., additional, and Talbot, Robert, additional
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- 2016
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106. NOx Lifetime and NOy Partitioning During WINTER.
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Kenagy, Hannah S., Sparks, Tamara L., Ebben, Carlena J., Wooldrige, Paul J., Lopez‐Hilfiker, Felipe D., Lee, Ben H., Thornton, Joel A., McDuffie, Erin E., Fibiger, Dorothy L., Brown, Steven S., Montzka, Denise D., Weinheimer, Andrew J., Schroder, Jason C., Campuzano‐Jost, Pedro, Day, Douglas A., Jimenez, Jose L., Dibb, Jack E., Campos, Teresa, Shah, Viral, and Jaeglé, Lyatt
- Subjects
ATMOSPHERIC nitrogen dioxide ,ATMOSPHERIC sciences ,NITROGEN dioxide & the environment ,WINTER ,ATMOSPHERIC aerosols - Abstract
Abstract: Although urban NO
x lifetimes have been examined extensively during summertime conditions, wintertime NOx chemistry has been comparatively less studied. We use measurements of NOx and its oxidation products from the aircraft‐based WINTER (Wintertime INvestigation of Transport, Emissions, and Reactivity) experiment over the northeastern United States during February–March 2015 to describe the NOx lifetime during conditions when days are shorter, actinic flux is reduced, and temperatures are colder. By analyzing regional outflow from the East Coast, we show that NOx is long lived during the winter, with a longer daytime lifetime (29 hr) than nighttime lifetime (6.3 hr). We demonstrate that wintertime NOx emissions have an overall lifetime controlled by the nighttime conversion of NOx to nitric acid (HNO3 ) via N2 O5 heterogeneous chemistry, and we discuss constraints on the rates of NOx conversion to HNO3 . Additionally, analysis of the nighttime Ox budget suggests that approximately 15% of O3 is lost overnight through N2 O5 production and subsequent reaction with aerosol to form HNO3 . [ABSTRACT FROM AUTHOR]- Published
- 2018
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- View/download PDF
107. Modeling NH4NO3 Over the San Joaquin Valley During the 2013 DISCOVER‐AQ Campaign.
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Kelly, James T., Parworth, Caroline L., Zhang, Qi, Miller, David J., Sun, Kang, Zondlo, Mark A., Baker, Kirk R., Wisthaler, Armin, Nowak, John B., Pusede, Sally E., Cohen, Ronald C., Weinheimer, Andrew J., Beyersdorf, Andreas J., Tonnesen, Gail S., Bash, Jesse O., Valin, Luke C., Crawford, James H., Fried, Alan, and Walega, James G.
- Abstract
Abstract: The San Joaquin Valley (SJV) of California experiences high concentrations of particulate matter NH
4 NO3 during episodes of meteorological stagnation in winter. A rich data set of observations related to NH4 NO3 formation was acquired during multiple periods of elevated NH4 NO3 during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER‐AQ) field campaign in SJV in January and February 2013. Here NH4 NO3 is simulated during the SJV DISCOVER‐AQ study period with the Community Multiscale Air Quality (CMAQ) model, diagnostic model evaluation is performed using the DISCOVER‐AQ data set, and integrated reaction rate analysis is used to quantify HNO3 production rates. Simulated NO3 − generally agrees well with routine monitoring of 24‐hr average NO3 − , but comparisons with hourly average NO3 − measurements in Fresno revealed differences at higher time resolution. Predictions of gas‐particle partitioning of total nitrate (HNO3 + NO3 − ) and NHx (NH3 + NH4 + ) generally agree well with measurements in Fresno, although partitioning of total nitrate to HNO3 is sometimes overestimated at low relative humidity in afternoon. Gas‐particle partitioning results indicate that NH4 NO3 formation is limited by HNO3 availability in both the model and ambient. NH3 mixing ratios are underestimated, particularly in areas with large agricultural activity, and additional work on the spatial allocation of NH3 emissions is warranted. During a period of elevated NH4 NO3 , the model predicted that the OH + NO2 pathway contributed 46% to total HNO3 production in SJV and the N2 O5 heterogeneous hydrolysis pathway contributed 54%. The relative importance of the OH + NO2 pathway for HNO3 production is predicted to increase as NOx emissions decrease. [ABSTRACT FROM AUTHOR]- Published
- 2018
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108. Heterogeneous N2O5 Uptake During Winter: Aircraft Measurements During the 2015 WINTER Campaign and Critical Evaluation of Current Parameterizations.
- Author
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McDuffie, Erin E., Fibiger, Dorothy L., Dubé, William P., Lopez‐Hilfiker, Felipe, Lee, Ben H., Thornton, Joel A., Shah, Viral, Jaeglé, Lyatt, Guo, Hongyu, Weber, Rodney J., Michael Reeves, J., Weinheimer, Andrew J., Schroder, Jason C., Campuzano‐Jost, Pedro, Jimenez, Jose L., Dibb, Jack E., Veres, Patrick, Ebben, Carly, Sparks, Tamara L., and Wooldridge, Paul J.
- Abstract
Abstract: Nocturnal dinitrogen pentoxide (N
2 O5 ) heterogeneous chemistry impacts regional air quality and the distribution and lifetime of tropospheric oxidants. Formed from the oxidation of nitrogen oxides, N2 O5 is heterogeneously lost to aerosol with a highly variable reaction probability, γ(N2 O5 ), dependent on aerosol composition and ambient conditions. Reaction products include soluble nitrate (HNO3 or NO3 − ) and nitryl chloride (ClNO2 ). We report the first‐ever derivations of γ(N2 O5 ) from ambient wintertime aircraft measurements in the critically important nocturnal residual boundary layer. Box modeling of the 2015 Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign over the eastern United States derived 2,876 individual γ(N2 O5 ) values with a median value of 0.0143 and range of 2 × 10−5 to 0.1751. WINTER γ(N2 O5 ) values exhibited the strongest correlation with aerosol water content, but weak correlations with other variables, such as aerosol nitrate and organics, suggesting a complex, nonlinear dependence on multiple factors, or an additional dependence on a nonobserved factor. This factor may be related to aerosol phase, morphology (i.e., core shell), or mixing state, none of which are commonly measured during aircraft field studies. Despite general agreement with previous laboratory observations, comparison of WINTER data with 14 literature parameterizations (used to predict γ(N2 O5 ) in chemical transport models) confirms that none of the current methods reproduce the full range of γ(N2 O5 ) values. Nine reproduce the WINTER median within a factor of 2. Presented here is the first field‐based, empirical parameterization of γ(N2 O5 ), fit to WINTER data, based on the functional form of previous parameterizations. [ABSTRACT FROM AUTHOR]- Published
- 2018
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109. Characterizing CO and NO<italic>y</italic> Sources and Relative Ambient Ratios in the Baltimore Area Using Ambient Measurements and Source Attribution Modeling.
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Simon, Heather, Valin, Luke C., Baker, Kirk R., Henderson, Barron H., Crawford, James H., Pusede, Sally E., Kelly, James T., Foley, Kristen M., Chris Owen, R., Cohen, Ronald C., Timin, Brian, Weinheimer, Andrew J., Possiel, Norm, Misenis, Chris, Diskin, Glenn S., and Fried, Alan
- Abstract
Abstract: Modeled source attribution information from the Community Multiscale Air Quality model was coupled with ambient data from the 2011 Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality Baltimore field study. We assess source contributions and evaluate the utility of using aircraft measured CO and NO
y relationships to constrain emission inventories. We derive ambient and modeled ΔCO:ΔNOy ratios that have previously been interpreted to represent CO:NOy ratios in emissions from local sources. Modeled and measured ΔCO:ΔNOy are similar; however, measured ΔCO:ΔNOy has much more daily variability than modeled values. Sector‐based tagging shows that regional transport, on‐road gasoline vehicles, and nonroad equipment are the major contributors to modeled CO mixing ratios in the Baltimore area. In addition to those sources, on‐road diesel vehicles, soil emissions, and power plants also contribute substantially to modeled NOy in the area. The sector mix is important because emitted CO:NOx ratios vary by several orders of magnitude among the emission sources. The model‐predicted gasoline/diesel split remains constant across all measurement locations in this study. Comparison of ΔCO:ΔNOy to emitted CO:NOy is challenged by ambient and modeled evidence that free tropospheric entrainment, and atmospheric processing elevates ambient ΔCO:ΔNOy above emitted ratios. Specifically, modeled ΔCO:ΔNOy from tagged mobile source emissions is enhanced 5–50% above the emitted ratios at times and locations of aircraft measurements. We also find a correlation between ambient formaldehyde concentrations and measured ΔCO:ΔNOy suggesting that secondary CO formation plays a role in these elevated ratios. This analysis suggests that ambient urban daytime ΔCO:ΔNOy values are not reflective of emitted ratios from individual sources. [ABSTRACT FROM AUTHOR]- Published
- 2018
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110. First Top‐Down Estimates of Anthropogenic NO<italic>x</italic> Emissions Using High‐Resolution Airborne Remote Sensing Observations.
- Author
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Souri, Amir H., Choi, Yunsoo, Pan, Shuai, Curci, Gabriele, Nowlan, Caroline R., Janz, Scott J., Kowalewski, Matthew G., Liu, Junjie, Herman, Jay R., and Weinheimer, Andrew J.
- Abstract
Abstract: A number of satellite‐based instruments have become an essential part of monitoring emissions. Despite sound theoretical inversion techniques, the insufficient samples and the footprint size of current observations have introduced an obstacle to narrow the inversion window for regional models. These key limitations can be partially resolved by a set of modest high‐quality measurements from airborne remote sensing. This study illustrates the feasibility of nitrogen dioxide (NO
2 ) columns from the Geostationary Coastal and Air Pollution Events Airborne Simulator (GCAS) to constrain anthropogenic NOx emissions in the Houston‐Galveston‐Brazoria area. We convert slant column densities to vertical columns using a radiative transfer model with (i) NO2 profiles from a high‐resolution regional model (1 × 1 km2 ) constrained by P‐3B aircraft measurements, (ii) the consideration of aerosol optical thickness impacts on radiance at NO2 absorption line, and (iii) high‐resolution surface albedo constrained by ground‐based spectrometers. We characterize errors in the GCAS NO2 columns by comparing them to Pandora measurements and find a striking correlation (r > 0.74) with an uncertainty of 3.5 × 1015 molecules cm−2 . On 9 of 10 total days, the constrained anthropogenic emissions by a Kalman filter yield an overall 2–50% reduction in polluted areas, partly counterbalancing the well‐documented positive bias of the model. The inversion, however, boosts emissions by 94% in the same areas on a day when an unprecedented local emissions event potentially occurred, significantly mitigating the bias of the model. The capability of GCAS at detecting such an event ensures the significance of forthcoming geostationary satellites for timely estimates of top‐down emissions. [ABSTRACT FROM AUTHOR]- Published
- 2018
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111. Wintertime Overnight NO<italic>x</italic> Removal in a Southeastern United States Coal‐fired Power Plant Plume: A Model for Understanding Winter NO<italic>x</italic> Processing and its Implications.
- Author
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Fibiger, Dorothy L., McDuffie, Erin E., Dubé, William P., Aikin, Kenneth C., Lopez‐Hilfiker, Felipe D., Lee, Ben H., Green, Jaime R., Fiddler, Marc N., Holloway, John S., Ebben, Carlena, Sparks, Tamara L., Wooldridge, Paul, Weinheimer, Andrew J., Montzka, Denise D., Apel, Eric C., Hornbrook, Rebecca S., Hills, Alan J., Blake, Nicola J., DiGangi, Josh P., and Wolfe, Glenn M.
- Abstract
Abstract: Nitric oxide (NO) is emitted in large quantities from coal‐burning power plants. During the day, the plumes from these sources are efficiently mixed into the boundary layer, while at night, they may remain concentrated due to limited vertical mixing during which they undergo horizontal fanning. At night, the degree to which NO is converted to HNO
3 and therefore unable to participate in next‐day ozone (O3 ) formation depends on the mixing rate of the plume, the composition of power plant emissions, and the composition of the background atmosphere. In this study, we use observed plume intercepts from the Wintertime INvestigation of Transport, Emissions and Reactivity campaign to test sensitivity of overnight NOx removal to the N2 O5 loss rate constant, plume mixing rate, background O3 , and background levels of volatile organic compounds using a 2‐D box model of power plant plume transport and chemistry. The factor that exerted the greatest control over NOx removal was the loss rate constant of N2 O5 . At the lowest observed N2 O5 loss rate constant, no other combination of conditions converts more than 10% of the initial NOx to HNO3 . The other factors did not influence NOx removal to the same degree. [ABSTRACT FROM AUTHOR]- Published
- 2018
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112. Rates of Wintertime Atmospheric SO2Oxidation based on Aircraft Observations during Clear‐Sky Conditions over the Eastern United States
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Green, Jaime R., Fiddler, Marc N., Holloway, John S., Fibiger, Dorothy L., McDuffie, Erin E., Campuzano‐Jost, Pedro, Schroder, Jason C., Jimenez, Jose L., Weinheimer, Andrew J., Aquino, Janine, Montzka, D. D., Hall, Samuel R., Ullmann, Kirk, Shah, Viral, Jaeglé, Lyatt, Thornton, Joel A., Bililign, Solomon, and Brown, Steven S.
- Abstract
Sulfur dioxide (SO2) is emitted in large quantities from coal‐burning power plants and leads to various harmful health and environmental effects. In this study, we use plume intercepts from the Wintertime INvestigation of Transport, Emission and Reactivity (WINTER) campaign to estimate the oxidation rates of SO2under wintertime conditions and the factors that determine SO2removal. Observations suggest that OH governs the rate SO2oxidation in the eastern United States during winter. The range of mean oxidation rates during the day from power plants were 0.22–0.71%/hr, producing SO2lifetimes of 13–43 days, if SO2consumption is assumed to occur during 10.5 hr of daylight in cloudless conditions. Though most nighttime rate measurements were zero within uncertainty, there is some evidence of nighttime removal, which suggests alternate oxidation mechanisms. The fastest nighttime observed SO2oxidation rate was 0.25±0.07%/hr, producing a combined day/night SO2lifetime of 8.5–21 days. The upper limit of the oxidation rate (the mean+1σof the fastest day and night observations) is 16.5%/day, corresponding to a lifetime of 6.1 days. The analysis also quantifies the primary emission of sulfate from power plants. The median mole percentage of SO4‐2from observed plumes was 1.7% and the mean percentage sulfate was 2.8% for intercepts within 1 hr of transit to power plants. The largest value observed from close intercepts was over 7% sulfate, and the largest extrapolated value was 18%, based on intercepts further from their source and fastest observed oxidation rate. The daytime conversion rate of SO2to SO4‐2was 0.22‐0.71%/hr in winter under clear‐sky conditions, with lifetimes of 140‐450 hrFor 10.5 hr of daylight, the upper limit of the oxidation rate is 16.5%/day, corresponding to a lifetime of 6.1 daysDirect emissions of SO4‐2relative to total sulfur (SO2+ SO4‐2) had mean and median values of 1.7% and 2.8%, respectively
- Published
- 2019
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113. Mercury Emission Ratios from Coal-Fired Power Plants in the Southeastern United States during NOMADSS
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Ambrose, Jesse L., primary, Gratz, Lynne E., additional, Jaffe, Daniel A., additional, Campos, Teresa, additional, Flocke, Frank M., additional, Knapp, David J., additional, Stechman, Daniel M., additional, Stell, Meghan, additional, Weinheimer, Andrew J., additional, Cantrell, Christopher A., additional, and Mauldin, Roy L., additional
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- 2015
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114. Evolution of NOx in the Denver Urban Plume during the Front Range Air Pollution and Photochemistry Experiment.
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Ebben, Carlena J., Sparks, Tamara L., Wooldridge, Paul J., Campos, Teresa L., Cantrell, Christopher A., Mauldin, Roy L., Weinheimer, Andrew J., and Cohen, Ronald C.
- Abstract
As NO
x (NOx ≡ NO + NO2 ) is transported away from cities, it undergoes photochemical oxidation to peroxynitrates (RO2 NO2 , ΣPNs), alkyl nitrates (RONO2 , ΣANs), and nitric acid (HNO3 ). These higher oxide species each have different lifetimes to permanent removal or conversion back to NOx , resulting in nitrogen oxide chemistry that evolves as plumes are transported away from cities. Here, observations from the Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) are used to describe the evolution of NOx and NOy (NOy ≡ NOx + ΣPNs + ΣANs + HNO3 + …) as the Denver urban plume flows outward from the city center. We evaluate the chemistry, dilution, and deposition rates in the plume to provide numerical constraints on the NOx and NOy,i lifetimes. We find that plume dilution with background air occurs with a lifetime of 3.5 hours. NOx concentrations decrease more rapidly with a lifetime to chemical loss and dilution of 2 hours in the near field of the city center. NOy has an effective lifetime of 3 hours and due to a combination of HNO3 deposition and dilution. The results provide a useful test of conceptual and numerical models of chemistry during the evolution of urban plumes. [ABSTRACT FROM AUTHOR]- Published
- 2017
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115. Large biogenic contribution to boundary layer O3-CO regression slope in summer.
- Author
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Cheng, Ye, Wang, Yuhang, Zhang, Yuzhong, Chen, Gao, Crawford, James H., Kleb, Mary M., Diskin, Glenn S., and Weinheimer, Andrew J.
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- 2017
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116. Ozone production and its sensitivity to NOx and VOCs: results from the DISCOVER-AQ field experiment, Houston 2013.
- Author
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Mazzuca, Gina M., Xinrong Ren, Loughner, Christopher P., Estes, Mark, Crawford, James H., Pickering, Kenneth E., Weinheimer, Andrew J., and Dickerson, Russell R.
- Subjects
ATMOSPHERIC ozone & the environment ,VOLATILE organic compounds & the environment ,NITRIC oxide & the environment ,METEOROLOGICAL observations ,PHOTOCHEMISTRY ,AIR quality ,CITIES & towns & the environment - Abstract
An observation-constrained box model based on the Carbon Bond mechanism, version 5 (CB05), was used to study photochemical processes along the NASA P-3B flight track and spirals over eight surface sites during the September 2013 Houston, Texas deployment of the NASA Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign. Data from this campaign provided an opportunity to examine and improve our understanding of atmospheric photochemical oxidation processes related to the formation of secondary air pollutants such as ozone (O
3 /. O3 production and its sensitivity to NOx and volatile organic compounds (VOCs) were calculated at different locations and times of day. Ozone production efficiency (OPE), defined as the ratio of the ozone production rate to the NOx oxidation rate, was calculated using the observations and the simulation results of the box and Community Multiscale Air Quality (CMAQ) models. Correlations of these results with other parameters, such as radical sources and NOx mixing ratio, were also evaluated. It was generally found that O3 production tends to be more VOC-sensitive in the morning along with high ozone production rates, suggesting that control of VOCs may be an effective way to control O3 in Houston. In the afternoon, O3 production was found to be mainly NOx -sensitive with some exceptions. O3 production near major emissions sources such as Deer Park was mostly VOC-sensitive for the entire day, other urban areas near Moody Tower and Channelview were VOC-sensitive or in the transition regime, and areas farther from downtown Houston such as Smith Point and Conroe were mostly NOx - sensitive for the entire day. It was also found that the control of NOx emissions has reduced O3 concentrations over Houston but has led to larger OPE values. The results from this work strengthen our understanding of O3 production; they indicate that controlling NOx emissions will provide air quality benefits over the greater Houston metropolitan area in the long run, but in selected areas controlling VOC emissions will also be beneficial. [ABSTRACT FROM AUTHOR]- Published
- 2016
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117. Chemical Methods: Chemiluminscence, Chemical Amplification, Electrochemistry, and Derivation
- Author
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Weinheimer, Andrew J, primary
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118. Convective transport of water vapor into the lower stratosphere observed during double-tropopause events
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Homeyer, Cameron R., primary, Pan, Laura L., additional, Dorsi, Samuel W., additional, Avallone, Linnea M., additional, Weinheimer, Andrew J., additional, O'Brien, Anthony S., additional, DiGangi, Joshua P., additional, Zondlo, Mark A., additional, Ryerson, Thomas B., additional, Diskin, Glenn S., additional, and Campos, Teresa L., additional
- Published
- 2014
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119. High levels of molecular chlorine in the Arctic atmosphere
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Liao, Jin, primary, Huey, L. Gregory, additional, Liu, Zhen, additional, Tanner, David J., additional, Cantrell, Chris A., additional, Orlando, John J., additional, Flocke, Frank M., additional, Shepson, Paul B., additional, Weinheimer, Andrew J., additional, Hall, Samuel R., additional, Ullmann, Kirk, additional, Beine, Harry J., additional, Wang, Yuhang, additional, Ingall, Ellery D., additional, Stephens, Chelsea R., additional, Hornbrook, Rebecca S., additional, Apel, Eric C., additional, Riemer, Daniel, additional, Fried, Alan, additional, Mauldin, Roy L., additional, Smith, James N., additional, Staebler, Ralf M., additional, Neuman, J. Andrew, additional, and Nowak, John B., additional
- Published
- 2014
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120. NOxLifetime and NOyPartitioning During WINTER
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Kenagy, Hannah S., Sparks, Tamara L., Ebben, Carlena J., Wooldrige, Paul J., Lopez‐Hilfiker, Felipe D., Lee, Ben H., Thornton, Joel A., McDuffie, Erin E., Fibiger, Dorothy L., Brown, Steven S., Montzka, Denise D., Weinheimer, Andrew J., Schroder, Jason C., Campuzano‐Jost, Pedro, Day, Douglas A., Jimenez, Jose L., Dibb, Jack E., Campos, Teresa, Shah, Viral, Jaeglé, Lyatt, and Cohen, Ronald C.
- Abstract
Although urban NOxlifetimes have been examined extensively during summertime conditions, wintertime NOxchemistry has been comparatively less studied. We use measurements of NOxand its oxidation products from the aircraft‐based WINTER (Wintertime INvestigation of Transport, Emissions, and Reactivity) experiment over the northeastern United States during February–March 2015 to describe the NOxlifetime during conditions when days are shorter, actinic flux is reduced, and temperatures are colder. By analyzing regional outflow from the East Coast, we show that NOxis long lived during the winter, with a longer daytime lifetime (29 hr) than nighttime lifetime (6.3 hr). We demonstrate that wintertime NOxemissions have an overall lifetime controlled by the nighttimeconversion of NOxto nitric acid (HNO3) via N2O5heterogeneous chemistry, and we discuss constraints on the rates of NOxconversion to HNO3. Additionally, analysis of the nighttime Oxbudget suggests that approximately 15% of O3is lost overnight through N2O5production and subsequent reaction with aerosol to form HNO3. The atmospheric lifetime (how long something persists in the atmosphere) and fate of nitrogen oxides in urban areas during the summer has been studied extensively, but relatively few studies have looked at the lifetime of nitrogen oxides in the atmosphere during winter. We use aircraft data from the East Coast of the United States during February–March 2015 to characterize the wintertime lifetime of nitrogen oxides when days are shorter, sunlight is reduced, and temperatures are colder. We are able to measure the wintertime lifetime of nitrogen oxides and assess the relative roles of mixing, deposition, and chemistry on their fate. We determine that nitrogen oxide loss during winter is dominated by nighttime rather than daytime chemistry and that this nighttime chemistry effectively removes ozone from the atmosphere. NOxis long lived during winter, with a longer daytime lifetime (29 hr) than nighttime lifetime (6.3 hr)Wintertime NOxlifetime is controlled by the nighttime conversion of NOxto HNO3via N2O5heterogeneous chemistryFifteen percent of O3is removed at night via the dark reactions of N2O5
- Published
- 2018
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- View/download PDF
121. Modeling NH4NO3Over the San Joaquin Valley During the 2013 DISCOVER‐AQ Campaign
- Author
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Kelly, James T., Parworth, Caroline L., Zhang, Qi, Miller, David J., Sun, Kang, Zondlo, Mark A., Baker, Kirk R., Wisthaler, Armin, Nowak, John B., Pusede, Sally E., Cohen, Ronald C., Weinheimer, Andrew J., Beyersdorf, Andreas J., Tonnesen, Gail S., Bash, Jesse O., Valin, Luke C., Crawford, James H., Fried, Alan, and Walega, James G.
- Abstract
The San Joaquin Valley (SJV) of California experiences high concentrations of particulate matter NH4NO3during episodes of meteorological stagnation in winter. A rich data set of observations related to NH4NO3formation was acquired during multiple periods of elevated NH4NO3during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER‐AQ) field campaign in SJV in January and February 2013. Here NH4NO3is simulated during the SJV DISCOVER‐AQ study period with the Community Multiscale Air Quality (CMAQ) model, diagnostic model evaluation is performed using the DISCOVER‐AQ data set, and integrated reaction rate analysis is used to quantify HNO3production rates. Simulated NO3−generally agrees well with routine monitoring of 24‐hr average NO3−, but comparisons with hourly average NO3−measurements in Fresno revealed differences at higher time resolution. Predictions of gas‐particle partitioning of total nitrate (HNO3+ NO3−) and NHx (NH3+ NH4+) generally agree well with measurements in Fresno, although partitioning of total nitrate to HNO3is sometimes overestimated at low relative humidity in afternoon. Gas‐particle partitioning results indicate that NH4NO3formation is limited by HNO3availability in both the model and ambient. NH3mixing ratios are underestimated, particularly in areas with large agricultural activity, and additional work on the spatial allocation of NH3emissions is warranted. During a period of elevated NH4NO3, the model predicted that the OH + NO2pathway contributed 46% to total HNO3production in SJV and the N2O5heterogeneous hydrolysis pathway contributed 54%. The relative importance of the OH + NO2pathway for HNO3production is predicted to increase as NOx emissions decrease. NH4NO3formation is limited by HNO3availability in both the model and ambient based on gas‐particle partitioning resultsThe OH + NO2pathway contributed 46% to modeled HNO3production in SJV, and the N2O5heterogeneous hydrolysis pathway contributed 54%The relative importance of the OH + NO2pathway for HNO3production is predicted to increase as NOx emissions decrease
- Published
- 2018
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122. Heterogeneous N2O5Uptake During Winter: Aircraft Measurements During the 2015 WINTER Campaign and Critical Evaluation of Current Parameterizations
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McDuffie, Erin E., Fibiger, Dorothy L., Dubé, William P., Lopez‐Hilfiker, Felipe, Lee, Ben H., Thornton, Joel A., Shah, Viral, Jaeglé, Lyatt, Guo, Hongyu, Weber, Rodney J., Michael Reeves, J., Weinheimer, Andrew J., Schroder, Jason C., Campuzano‐Jost, Pedro, Jimenez, Jose L., Dibb, Jack E., Veres, Patrick, Ebben, Carly, Sparks, Tamara L., Wooldridge, Paul J., Cohen, Ronald C., Hornbrook, Rebecca S., Apel, Eric C., Campos, Teresa, Hall, Samuel R., Ullmann, Kirk, and Brown, Steven S.
- Abstract
Nocturnal dinitrogen pentoxide (N2O5) heterogeneous chemistry impacts regional air quality and the distribution and lifetime of tropospheric oxidants. Formed from the oxidation of nitrogen oxides, N2O5is heterogeneously lost to aerosol with a highly variable reaction probability, γ(N2O5), dependent on aerosol composition and ambient conditions. Reaction products include soluble nitrate (HNO3or NO3−) and nitryl chloride (ClNO2). We report the first‐ever derivations of γ(N2O5) from ambient wintertime aircraft measurements in the critically important nocturnal residual boundary layer. Box modeling of the 2015 Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign over the eastern United States derived 2,876 individual γ(N2O5) values with a median value of 0.0143 and range of 2 × 10−5to 0.1751. WINTER γ(N2O5) values exhibited the strongest correlation with aerosol water content, but weak correlations with other variables, such as aerosol nitrate and organics, suggesting a complex, nonlinear dependence on multiple factors, or an additional dependence on a nonobserved factor. This factor may be related to aerosol phase, morphology (i.e., core shell), or mixing state, none of which are commonly measured during aircraft field studies. Despite general agreement with previous laboratory observations, comparison of WINTER data with 14 literature parameterizations (used to predict γ(N2O5) in chemical transport models) confirms that none of the current methods reproduce the full range of γ(N2O5) values. Nine reproduce the WINTER median within a factor of 2. Presented here is the first field‐based, empirical parameterization of γ(N2O5), fit to WINTER data, based on the functional form of previous parameterizations. Aircraft measurements over the eastern United States provide the largest number of N2O5uptake coefficient γ(N2O5) determinations during winterDespite a large range and variability, several γ(N2O5) dependencies are statistically significant, particularly with aerosol liquid waterStandard γ(N2O5) parameterizations do not capture the variability but several, including an empirical form derived here, capture the median
- Published
- 2018
- Full Text
- View/download PDF
123. Wintertime Overnight NOxRemoval in a Southeastern United States Coal‐fired Power Plant Plume: A Model for Understanding Winter NOxProcessing and its Implications
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Fibiger, Dorothy L., McDuffie, Erin E., Dubé, William P., Aikin, Kenneth C., Lopez‐Hilfiker, Felipe D., Lee, Ben H., Green, Jaime R., Fiddler, Marc N., Holloway, John S., Ebben, Carlena, Sparks, Tamara L., Wooldridge, Paul, Weinheimer, Andrew J., Montzka, Denise D., Apel, Eric C., Hornbrook, Rebecca S., Hills, Alan J., Blake, Nicola J., DiGangi, Josh P., Wolfe, Glenn M., Bililign, Solomon, Cohen, Ronald C., Thornton, Joel A., and Brown, Steven S.
- Abstract
Nitric oxide (NO) is emitted in large quantities from coal‐burning power plants. During the day, the plumes from these sources are efficiently mixed into the boundary layer, while at night, they may remain concentrated due to limited vertical mixing during which they undergo horizontal fanning. At night, the degree to which NO is converted to HNO3and therefore unable to participate in next‐day ozone (O3) formation depends on the mixing rate of the plume, the composition of power plant emissions, and the composition of the background atmosphere. In this study, we use observed plume intercepts from the Wintertime INvestigation of Transport, Emissions and Reactivity campaign to test sensitivity of overnight NOxremoval to the N2O5loss rate constant, plume mixing rate, background O3, and background levels of volatile organic compounds using a 2‐D box model of power plant plume transport and chemistry. The factor that exerted the greatest control over NOxremoval was the loss rate constant of N2O5. At the lowest observed N2O5loss rate constant, no other combination of conditions converts more than 10% of the initial NOxto HNO3. The other factors did not influence NOxremoval to the same degree. N2O5loss rate is main factor controlling overnight NOxloss via conversion to HNO3in power plant plumesFate of organic nitrates is important factor in degree of overnight NOxremoval from power plant plumesExtremely low N2O5loss rate constant and uptake coefficients observed in plume are below most prior observations
- Published
- 2018
- Full Text
- View/download PDF
124. Ozone correlations between mid-tropospheric partial columns and the near-surface at two mid-atlantic sites during the DISCOVER-AQ campaign in July 2011
- Author
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Martins, Douglas K., primary, Stauffer, Ryan M., additional, Thompson, Anne M., additional, Halliday, Hannah S., additional, Kollonige, Debra, additional, Joseph, Everette, additional, and Weinheimer, Andrew J., additional
- Published
- 2013
- Full Text
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125. The electric field alignment of ice particles in thunderstorms
- Author
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Weinheimer, Andrew J and Few, Arthur A
- Subjects
Meteorology And Climatology - Abstract
Electrical and aerodynamic torques on atmospheric ice particles are calculaed in order to assess the degree of alignment of these particles with the electric fields in thunderstorms. In such clouds fields of many tens of kilovolts per meter are commonly measured, and values of 100 to 200 kV/m are not rare. For E = 100 kV/m the calculations indicate that electric field alignment occurs for crystals with major dimensions up to maximum values in the range from 200 microns to 1 mm, depending upon crystal type. Columns are aligned more easily than platelike crystals, except for dendrites which, by virtue of their smaller assumed density, have smaller fall velocities thereby experiencing weaker aerodynamic torques. Thus a substantial degree of alignment is expected for E = 100 kV/m. For E = 10 kV/m only much smaller crystals will be aligned, probably only ones with major dimensions of less than 50 microns or so.
- Published
- 1987
126. Chemical Methods: Chemiluminescence, Chemical Amplification, Electrochemistry, and Derivatization
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Weinheimer, Andrew J., primary
- Published
- 2007
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127. Transport in the subtropical lowermost stratosphere during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers–Florida Area Cirrus Experiment
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Pittman, Jasna V., primary, Weinstock, Elliot M., additional, Oglesby, Robert J., additional, Sayres, David S., additional, Smith, Jessica B., additional, Anderson, James G., additional, Cooper, Owen R., additional, Wofsy, Steven C., additional, Xueref, Irene, additional, Gerbig, Cristoph, additional, Daube, Bruce C., additional, Richard, Erik C., additional, Ridley, Brian A., additional, Weinheimer, Andrew J., additional, Loewenstein, Max, additional, Jost, Hans-Jurg, additional, Lopez, Jimena P., additional, Mahoney, Michael J., additional, Thompson, Thomas L., additional, Hargrove, William W., additional, and Hoffman, Forrest M., additional
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- 2007
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- View/download PDF
128. Book review
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Weinheimer, Andrew J.
- Published
- 1987
- Full Text
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129. Deep convection as a source of new particles in the midlatitude upper troposphere
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Twohy, Cynthia H., primary, Clement, Charles F., additional, Gandrud, Bruce W., additional, Weinheimer, Andrew J., additional, Campos, Teresa L., additional, Baumgardner, Darrel, additional, Brune, William H., additional, Faloona, Ian, additional, Sachse, Glen W., additional, Vay, Stephanie A., additional, and Tan, David, additional
- Published
- 2002
- Full Text
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130. A Two-Path, Two-Wavelength Ultraviolet Hygrometer
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Weinheimer, Andrew J., primary and Schwiesow, Ronald L., additional
- Published
- 1992
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- View/download PDF
131. A cautionary note on the use of some mass flow controllers
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Weinheimer, Andrew J., primary and Ridley, Brian A., additional
- Published
- 1990
- Full Text
- View/download PDF
132. The electrostatic energy of a thunderstorm and its rate of change.
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Weinheimer, Andrew J.
- Published
- 1987
- Full Text
- View/download PDF
133. The application of potential flow theory to the rotational dynamics of spheroids, disks, and cylinders.
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Weinheimer, Andrew J. and Few, Arthur A.
- Published
- 1985
- Full Text
- View/download PDF
134. The spokes in Saturn's rings: A critical evaluation of possible electrical processes.
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Weinheimer, Andrew J. and Few, Arthur A.
- Published
- 1982
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135. Letters.
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Weinheimer, Andrew J. and Knight, Charles A.
- Subjects
- *
HALOS (Meteorology) , *METEOROLOGICAL optics , *ATMOSPHERIC physics , *METEOROLOGY - Abstract
Comments on an article which was published in the May 1987 edition of the periodical 'Scientific American,' and focused on the portrayal of the uncertainties connected with the Scheiner's halo.
- Published
- 1987
- Full Text
- View/download PDF
136. Comment [on 'Contributions of cloud and precipitation particles to the electrical conductivity and the relaxation time of the air in thunderstorms' by A. K. Kamra].
- Author
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Weinheimer, Andrew J. and Few, Arthur A.
- Published
- 1981
- Full Text
- View/download PDF
137. Evidence of Nighttime Production of Organic Nitrates During SEAC4RS, FRAPPÉ, and KORUS‐AQ
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Kenagy, Hannah S., Sparks, Tamara L., Wooldridge, Paul J., Weinheimer, Andrew J., Ryerson, Thomas B., Blake, Donald R., Hornbrook, Rebecca S., Apel, Eric C., and Cohen, Ronald C.
- Abstract
Organic nitrates (RONO2) are an important NOxsink. In warm, rural environments dominated by biogenic emissions, nocturnal NO3‐initiated production of RONO2is competitive with daytime OH‐initiated RONO2production. However, in urban areas, OH‐initiated production of RONO2has been assumed dominant and NO3‐initiated production considered negligible. We show evidence for nighttime RONO2production similar in magnitude to daytime production during three aircraft campaigns in chemically distinct summertime environments: Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS) in the rural Southeastern United States, Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) in the Colorado Front Range, and Korea‐United States Air Quality Study (KORUS‐AQ) around the megacity of Seoul. During each campaign, morning observations show RONO2enhancements at constant, near‐background Ox(≡ O3+NO2) concentrations, indicating that the RONO2are from a non‐photochemical source, whereas afternoon observations show a strong correlation between RONO2and Oxresulting from photochemical production. We show that there are sufficient precursors for nighttime RONO2formation during all three campaigns. This evidence impacts our understanding of nighttime NOxchemistry. Nitrogen oxides are pollutants emitted during combustion which are involved in ozone and secondary aerosol production. One way in which nitrogen oxides are removed from the atmosphere is via chemistry that converts them to organic nitrates. This conversion of nitrogen oxides to organic nitrates has been thought to occur primarily during the day when the chemistry is driven by sunlight. Here we show evidence that nighttime processes generate similar quantities of organic nitrates to those produced by sunlight‐driven processes. We show evidence for nocturnal production of organic nitrates similar in magnitude to daytime photochemical productionSignificant nocturnal production of organic nitrates observed from three aircraft campaigns in distinct environmentsNighttime production of organic nitrates impacts our understanding of the nighttime lifetime and fate of NOx
- Published
- 2020
- Full Text
- View/download PDF
138. ClNO2 Yields From Aircraft Measurements During the 2015 WINTER Campaign and Critical Evaluation of the Current Parameterization.
- Author
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McDuffie, Erin E., Fibiger, Dorothy L., Dubé, William P., Lopez Hilfiker, Felipe, Lee, Ben H., Jaeglé, Lyatt, Guo, Hongyu, Weber, Rodney J., Reeves, J. Michael, Weinheimer, Andrew J., Schroder, Jason C., Campuzano‐Jost, Pedro, Jimenez, Jose L., Dibb, Jack E., Veres, Patrick, Ebben, Carlena, Sparks, Tamara L., Wooldridge, Paul J., Cohen, Ronald C., and Campos, Teresa
- Subjects
ATMOSPHERIC aerosols ,HALOGENS ,BOX models (Climatology) ,VOLATILE organic compounds ,TROPOSPHERE - Abstract
Nitryl chloride (ClNO2) plays an important role in the budget and distribution of tropospheric oxidants, halogens, and reactive nitrogen species. ClNO2 is formed from the heterogeneous uptake and reaction of dinitrogen pentoxide (N2O5) on chloride‐containing aerosol, with a production yield, ϕ(ClNO2), defined as the moles of ClNO2 produced relative to N2O5 lost. The ϕ(ClNO2) has been increasingly incorporated into 3‐D chemical models where it is parameterized based on laboratory‐derived kinetics and currently accepted aqueous‐phase formation mechanism. This parameterization models ϕ(ClNO2) as a function of the aerosol chloride to water molar ratio. Box model simulations of night flights during the 2015 Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) aircraft campaign derived 3,425 individual ϕ(ClNO2) values with a median of 0.138 and range of 0.003 to 1. Comparison of the box model median to those predicted by two other field‐based ϕ(ClNO2) derivation methods agreed within a factor of 1.3, within the uncertainties of each method. In contrast, the box model median was 75–84% lower than predictions from the laboratory‐based parameterization (i.e., [parameterization − box model]/parameterization). An evaluation of factors influencing this difference reveals a positive dependence of ϕ(ClNO2) on aerosol water, opposite to the currently parameterized trend. Additional factors may include aqueous‐phase competition reactions for the nitronium ion intermediate and/or direct ClNO2 loss mechanisms. Further laboratory studies of ClNO2 formation and the impacts of aerosol water, sulfate, organics, and ClNO2 aqueous‐phase reactions are required to elucidate and quantify these processes on ambient aerosol, critical for the development of a robust ϕ(ClNO2) parameterization. Key Points: Box modeling of wintertime measurements over the eastern United States provides the first determinations of ClNO2 yields (ϕ(ClNO2)) from aircraftThe median ϕ(ClNO2) value derived from the box model is overpredicted by 75‐84% by the current laboratory‐based ϕ(ClNO2) parameterizationModeled and parameterized ϕ(ClNO2) values show opposite trends with aerosol water, suggesting an incorrectly parameterized dependence [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
139. Effects of aging on organic aerosol from open biomass burning smoke in aircraft & lab studies
- Author
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Jose L Jimenez, Cubison, Michael J., Ortega, Amber M., Hayes, Patrick L., Farmer, Delphine K., Day, Douglas A., Lechner, Michael J., Brune, William H., Apel, Eric, Diskin, Glenn S., Fisher, Jenny A., Fuelberg, Henry A., Hecobian, Arsineh, Knapp, David J., Mikoviny, Tomas, Riemer, Daniel, Sachse, Glen W., Sessions, Walter, Weber, Rodney J., Weinheimer, Andrew J., and Wisthaler, Armin
140. Mathematical note on the Kerr effect
- Author
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Weinheimer, Andrew J., primary
- Published
- 1985
- Full Text
- View/download PDF
141. Scheiner's Halo: Cubic Ice or Polycrystalline Hexagonal Ice?
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Weinheimer, Andrew J., primary and Knight, Charles A., additional
- Published
- 1987
- Full Text
- View/download PDF
142. Application of the Stokes Drag on Spheroids to the Drag on Disks and Cylinders
- Author
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Weinheimer, Andrew J., primary
- Published
- 1987
- Full Text
- View/download PDF
143. The Simple Rectification to Cartesian Space of Folded Radial Velocities from Doppler Radar Sampling
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Jay Miller, L., primary, Mohr, Carl G., additional, and Weinheimer, Andrew J., additional
- Published
- 1986
- Full Text
- View/download PDF
144. The Electro-Optical Kerr Effect in the Atmosphere
- Author
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Weinheimer, Andrew J., primary
- Published
- 1986
- Full Text
- View/download PDF
145. The Charge Induced on a Conducting Cylinder by a Point Charge and Its Application to the Measurement of Charge on Precipitation
- Author
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Weinheimer, Andrew J., primary
- Published
- 1988
- Full Text
- View/download PDF
146. What size of ice crystals causes the halos?: comment
- Author
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Weinheimer, Andrew J., primary
- Published
- 1986
- Full Text
- View/download PDF
147. Sensitivity of the WRF-Chem v4.4 simulations of ozone and formaldehyde and their precursors to multiple bottom-up emission inventories over East Asia during the KORUS-AQ 2016 field campaign.
- Author
-
Kim, Kyoung-Min, Kim, Si-Wan, Seo, Seunghwan, Blake, Donald R., Cho, Seogju, Crawford, James H., Emmons, Louisa K., Fried, Alan, Herman, Jay R., Hong, Jinkyu, Jung, Jinsang, Pfister, Gabriele G., Weinheimer, Andrew J., Woo, Jung-Hun, and Zhang, Qiang
- Subjects
- *
EMISSION inventories , *OZONE , *VOLATILE organic compounds , *FORMALDEHYDE , *METROPOLITAN areas , *AIR quality - Abstract
In this study, the WRF-Chem v4.4 model was utilized to evaluate the sensitivity of O 3 simulations with three bottom-up emission inventories (EDGAR-HTAP v2 and v3 and KORUS v5) using surface and aircraft data in East Asia during the Korea-United States Air Quality (KORUS-AQ) campaign period in 2016. All emission inventories were found to reproduce the diurnal variations of O 3 and its main precursor NO 2 as compared to the surface monitor data. However, the spatial distributions of the daily maximum 8 h average (MDA8) O 3 in the model do not completely align with the observations. The model MDA8 O 3 had a negative (positive) bias north (south) of 30° N over China. All simulations underestimated the observed CO by 50 %–60 % over China and South Korea. In the Seoul Metropolitan Area (SMA), EDGAR-HTAP v2 and v3 and KORUS v5 simulated the vertical shapes and diurnal patterns of O 3 and other precursors effectively, but the model underestimated the observed O 3 , CO, and HCHO concentrations. Notably, the model aromatic volatile organic compounds (VOCs) were significantly underestimated with the three bottom-up emission inventories, although the KORUS v5 shows improvements. The model isoprene estimations had a positive bias relative to the observations, suggesting that the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.04 overestimated isoprene emissions. Additional model simulations were conducted by doubling CO and VOC emissions over China and South Korea to investigate the causes of the model O 3 biases and the effects of the long-range transport on the O 3 over South Korea. The doubled CO and VOC emission simulations improved the model O 3 simulations for the local-emission-dominant case but led to the model O 3 overestimations for the transport-dominant case, which emphasizes the need for accurate representations of the local VOC emissions over South Korea. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
148. ClNO2Yields From Aircraft Measurements During the 2015 WINTER Campaign and Critical Evaluation of the Current Parameterization
- Author
-
McDuffie, Erin E., Fibiger, Dorothy L., Dubé, William P., Lopez Hilfiker, Felipe, Lee, Ben H., Jaeglé, Lyatt, Guo, Hongyu, Weber, Rodney J., Reeves, J. Michael, Weinheimer, Andrew J., Schroder, Jason C., Campuzano‐Jost, Pedro, Jimenez, Jose L., Dibb, Jack E., Veres, Patrick, Ebben, Carlena, Sparks, Tamara L., Wooldridge, Paul J., Cohen, Ronald C., Campos, Teresa, Hall, Samuel R., Ullmann, Kirk, Roberts, James M., Thornton, Joel A., and Brown, Steven S.
- Abstract
Nitryl chloride (ClNO2) plays an important role in the budget and distribution of tropospheric oxidants, halogens, and reactive nitrogen species. ClNO2is formed from the heterogeneous uptake and reaction of dinitrogen pentoxide (N2O5) on chloride‐containing aerosol, with a production yield, ϕ(ClNO2), defined as the moles of ClNO2produced relative to N2O5lost. The ϕ(ClNO2) has been increasingly incorporated into 3‐D chemical models where it is parameterized based on laboratory‐derived kinetics and currently accepted aqueous‐phase formation mechanism. This parameterization models ϕ(ClNO2) as a function of the aerosol chloride to water molar ratio. Box model simulations of night flights during the 2015 Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) aircraft campaign derived 3,425 individual ϕ(ClNO2) values with a median of 0.138 and range of 0.003 to 1. Comparison of the box model median to those predicted by two other field‐based ϕ(ClNO2) derivation methods agreed within a factor of 1.3, within the uncertainties of each method. In contrast, the box model median was 75–84% lower than predictions from the laboratory‐based parameterization (i.e., [parameterization − box model]/parameterization). An evaluation of factors influencing this difference reveals a positive dependence of ϕ(ClNO2) on aerosol water, opposite to the currently parameterized trend. Additional factors may include aqueous‐phase competition reactions for the nitronium ion intermediate and/or direct ClNO2loss mechanisms. Further laboratory studies of ClNO2formation and the impacts of aerosol water, sulfate, organics, and ClNO2aqueous‐phase reactions are required to elucidate and quantify these processes on ambient aerosol, critical for the development of a robust ϕ(ClNO2) parameterization. Box modeling of wintertime measurements over the eastern United States provides the first determinations of ClNO2yields (ϕ(ClNO2)) from aircraftThe median ϕ(ClNO2) value derived from the box model is overpredicted by 75‐84% by the current laboratory‐based ϕ(ClNO2) parameterizationModeled and parameterized ϕ(ClNO2) values show opposite trends with aerosol water, suggesting an incorrectly parameterized dependence
- Published
- 2018
- Full Text
- View/download PDF
149. Sensitivity of the WRF-Chem v4.4 ozone, formaldehyde, and precursor simulations to multiple bottom-up emission inventories over East Asia during the KORUS-AQ 2016 field campaign.
- Author
-
Kyoung-Min Kim, Si-Wan Kim, Seunghwan Seo, Blake, Donald R., Seogju Cho, Crawford, James H., Emmons, Louisa, Fried, Alan, Herman, Jay R., Jinkyu Hong, Jinsang Jung, Pfister, Gabriele, Weinheimer, Andrew J., Jung-Hun Woo, and Qiang Zhang
- Subjects
- *
EMISSION inventories , *OZONE , *FORMALDEHYDE , *METROPOLITAN areas , *AIR quality , *MODEL airplanes - Abstract
In this study, the WRF-Chem v4.4 model was utilized to evaluate three bottom-up emission inventories (EDGAR-HTAP v2, v3, and KORUS v5) using surface and aircraft data in East Asia during the Korea-United States Air Quality (KORUS-AQ) campaign period in 2016. All emission inventories were found to reproduce the diurnal variations of O3 and NO2 as compared to the surface monitor data. However, the spatial distributions of the daily maximum 8-hour average (MDA8) O3 in the model do not completely align with the observations. The model MDA8 O3 had a negative (positive) bias north (south) of 30°N over China. All simulations underestimated the observed CO by 50-60% over China and South Korea. In the Seoul Metropolitan Area (SMA), EDGAR-HTAP v2, v3, and KORUS v5 simulated the vertical shapes and diurnal patterns of O3 and other precursors effectively, but the model underestimated the observed O3, CO and HCHO concentrations. Notably, the model aromatic VOCs were significantly underestimated with the three bottom-up emission inventories, although the KORUS v5 shows improvements. The model isoprene estimations had a positive bias relative to the observations, suggesting that the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.04 overestimated isoprene emissions. Additional model simulations were conducted by doubling CO and VOC emissions over China and South Korea to investigate the causes of the model O3 biases and the effects of the long-range transport on the O3 over South Korea. The doubled CO and VOC emission simulations improved the model O3 simulations for the local emission dominant case, but led to the model O3 overestimations for the transport dominant case, which emphasizes the need for accurate representations of the local VOC emissions over South Korea. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
150. Direct Constraints on Secondary HONO Production in Aged Wildfire Smoke From Airborne Measurements Over the Western US.
- Author
-
Peng, Qiaoyun, Palm, Brett B., Fredrickson, Carley D., Lee, Ben H., Hall, Samuel R., Ullmann, Kirk, Weinheimer, Andrew J., Levin, Ezra, DeMott, Paul, Garofalo, Lauren A., Pothier, Matson A., Farmer, Delphine K., Fischer, Emily V., and Thornton, Joel A.
- Subjects
- *
SMOKE plumes , *PARTICULATE nitrate , *SMOKE , *CHEMICAL processes , *WILDFIRES , *CHEMICAL amplification , *TOBACCO smoke , *WILDFIRE prevention - Abstract
Nitrous acid (HONO) mixing ratios measured in aged wildfire smoke plumes were higher than expected from known homogeneous chemical reactions. In a representative smoke plume, intercepted hours to days downwind of the source, the missing HONO source was highly correlated to particulate nitrate photolysis and NO2 reactive uptake to particles. Using a multilinear regression involving these two sources, we could explain the missing HONO production in this plume (R2 = 0.77). The resulting fit parameters from this plume had good explanatory power (R2 = 0.64) for missing HONO production in other fire plumes. The mean enhancement factor for particulate nitrate photolysis relative to gas‐phase nitric acid photolysis was 63 and the mean NO2 reactive uptake coefficient to submicron aerosol surface area forming HONO was 4.9 × 10−4. Given the likelihood of other neglected secondary HONO sources, these values are upper‐limits, suggesting a need to revisit HONO formation mechanisms in aged wildfire smoke. Plain Language Summary: A river of smoke from multiple wildfires was sampled far downwind and served as a natural laboratory for evaluating sources of nitrous acid (HONO) in aged wildfire smoke. HONO photolysis is an important source of reactive oxidants that initiate chemical transformations of wildfire emissions. We demonstrate that sources of HONO from chemical processes, known as secondary HONO sources, can largely be explained by two processes – the photolysis of particulate nitrate and the reactive uptake of nitrogen dioxide (NO2) to smoke aerosol particles. High time resolution in situ observations of HONO and auxiliary measurements were used to map out variations in the missing HONO source across a wide span of wildfire characteristics. The results place an upper limit on the magnitude of HONO sources from particulate nitrate photolysis, and suggest that the heterogeneous NO2 reactive uptake to smoke particles could be more important than previous field studies have indicated. These findings demonstrate the existence of additional processes other than direct emissions responsible for HONO formation in fire smoke. This secondary HONO source could increase the oxidizing capacity of wildfire smoke plumes significantly downwind of the emission source and therefore affect the formation and lifetime of other secondary wildfire smoke components. Key Points: Secondary multi‐phase processes dominate daytime HONO levels in aged (>3 hr) fire smokeThe inferred strength of secondary HONO production is most correlated to NO2, aerosol surface area, and particulate nitrateWe find significantly weaker HONO formation from particulate nitrate photolysis than previous reports [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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