The data includes (1) one zip file of CMAQ code used for simulations in the manuscript and (2) a link to field data (total alkyl nitrates) used for evaluation. See S-T13-TNO2ANsPNsTDLIF_CTR_20130601_RE.ict at the link for measurement information. For other information, please contact the corresponding authors Havala Pye (pye.havala@epa.gov) and Ron Cohen. This dataset is associated with the following publication: Zare, A., K. Fahey, G. Sarwar, R. Cohen, and H. Pye. Vapor-Pressure Pathways Initiate but Hydrolysis Products Dominate the Aerosol Estimated from Organic Nitrates. ACS Earth and Space Chemistry. American Chemical Society, Washington, DC, USA, 3(8): 1426-1437, (2019).

This data documents the results of chamber modeling and chemical transport modeling of the contribution of Intermediate Volatility Organic Compounds to mobile-source organic aerosol formation in California. The data show that IVOCs make up a significant fraction of the total source of secondary organic aerosol in urban environments and that mobile sources make up only about one third to half of the total IVOC emissions. Other urban sources of IVOCs were explored. These data are visualized and presented in the figures published in a peer-reviewed manuscript (with corresponding title) in Atmospheric Chemistry and Physics. The raw CMAQ output data are backed up and preserved on the ATMOS supercomputing system at the National Computing Center in Durham, North Carolina. The file location on the ASM server is: /asm/MOD3DEV/bmurphy/Models/cmaq/CMAQ_Ben/Projects/quanyang_181212/data. This dataset is associated with the following publication: Lu, Q., B. Murphy, M. Qin, P.J. Adams, Y. Zhao, H. Pye, C. Efstathiou, C. Allen, and A. Robinson. Simulation of organic aerosol formation during the CalNex study: updated mobile emissions and secondary organic aerosol parameterization for intermediate-volatility organic compounds. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 20(7): 4313–4332, (2020).

This data documents the results of chamber modeling and chemical transport modeling of the contribution of Intermediate Volatility Organic Compounds to mobile-source organic aerosol formation in California. The data show that IVOCs make up a significant fraction of the total source of secondary organic aerosol in urban environments and that mobile sources make up only about one third to half of the total IVOC emissions. Other urban sources of IVOCs were explored. These data are visualized and presented in the figures published in a peer-reviewed manuscript (with corresponding title) in Atmospheric Chemistry and Physics. The raw CMAQ output data are backed up and preserved on the ATMOS supercomputing system at the National Computing Center in Durham, North Carolina. The file location on the ASM server is: /asm/MOD3DEV/bmurphy/Models/cmaq/CMAQ_Ben/Projects/quanyang_181212/data. This dataset is associated with the following publication: Lu, Q., B. Murphy, M. Qin, P.J. Adams, Y. Zhao, H. Pye, C. Efstathiou, C. Allen, and A. Robinson. Simulation of organic aerosol formation during the CalNex study: updated mobile emissions and secondary organic aerosol parameterization for intermediate-volatility organic compounds. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 20(7): 4313–4332, (2020).

Data contains CMAQ code, VCPy code, CMAQ input files, and output files used in the work of Pennington et al.

Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes and sesquiterpenes are important precursors of secondary organic aerosol (SOA), but the amounts and pathways of SOA generation from these precursors are not well constrained by observations. We propose that the less-oxidized oxygenated organic aerosol (LO-OOA) factor resolved from positive matrix factorization (PMF) analysis on aerosol mass spectrometry (AMS) data can be used as a surrogate for fresh SOA from monoterpenes and sesquiterpenes in the southeastern US. This hypothesis is supported by multiple lines of evidence, including lab-in-the-field perturbation experiments, extensive ambient ground-level measurements, and state-of-the-art modeling. We performed lab-in-the-field experiments in which the ambient air is perturbed by the injection of selected monoterpenes and sesquiterpenes, and the subsequent SOA formation is investigated. PMF analysis on the perturbation experiments provides an objective link between LO-OOA and fresh SOA from monoterpenes and sesquiterpenes as well as insights into the sources of other OA factors. Further, we use an upgraded atmospheric model and show that modeled SOA concentrations from monoterpenes and sesquiterpenes could reproduce both the magnitude and diurnal variation of LO-OOA at multiple sites in the southeastern US, building confidence in our hypothesis. We estimate the annual average concentration of SOA from monoterpenes and sesquiterpenes in the southeastern US to be roughly 2µgm−3. Dataset (csv file) contains CMAQ model predictions for locations in the southeastern US during 2012 and 2013. The species definition file (txt) defines how quantities were obtained from the model. Data in the csv files follows the writesite utility output format (https://github.com/USEPA/CMAQ/tree/5.2.1/POST/writesite). Links to additional datasets are provided. This dataset is associated with the following publication: Xu, L., H. Pye, J. He, Y. Chen, B. Murphy, and N. Ng. Experimental and model estimates of the contributions from biogenic monoterpenes and sesquiterpenes to secondary organic aerosol in the southeastern United States. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 18(17): 12613-12637, (2018).

Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes and sesquiterpenes are important precursors of secondary organic aerosol (SOA), but the amounts and pathways of SOA generation from these precursors are not well constrained by observations. We propose that the less-oxidized oxygenated organic aerosol (LO-OOA) factor resolved from positive matrix factorization (PMF) analysis on aerosol mass spectrometry (AMS) data can be used as a surrogate for fresh SOA from monoterpenes and sesquiterpenes in the southeastern US. This hypothesis is supported by multiple lines of evidence, including lab-in-the-field perturbation experiments, extensive ambient ground-level measurements, and state-of-the-art modeling. We performed lab-in-the-field experiments in which the ambient air is perturbed by the injection of selected monoterpenes and sesquiterpenes, and the subsequent SOA formation is investigated. PMF analysis on the perturbation experiments provides an objective link between LO-OOA and fresh SOA from monoterpenes and sesquiterpenes as well as insights into the sources of other OA factors. Further, we use an upgraded atmospheric model and show that modeled SOA concentrations from monoterpenes and sesquiterpenes could reproduce both the magnitude and diurnal variation of LO-OOA at multiple sites in the southeastern US, building confidence in our hypothesis. We estimate the annual average concentration of SOA from monoterpenes and sesquiterpenes in the southeastern US to be roughly 2µgm−3. Dataset (csv file) contains CMAQ model predictions for locations in the southeastern US during 2012 and 2013. The species definition file (txt) defines how quantities were obtained from the model. Data in the csv files follows the writesite utility output format (https://github.com/USEPA/CMAQ/tree/5.2.1/POST/writesite). Links to additional datasets are provided. This dataset is associated with the following publication: Xu, L., H. Pye, J. He, Y. Chen, B. Murphy, and N. Ng. Experimental and model estimates of the contributions from biogenic monoterpenes and sesquiterpenes to secondary organic aerosol in the southeastern United States. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 18(17): 12613-12637, (2018).

EPA did not generate data as part of this work. This dataset is not publicly accessible because: I personally did not generate any new data in this study. It can be accessed through the following means: Via contact with corresponding author. Format: This study was led by the University of North Carolina at Chapel Hill and they plan to distribute through Mendeley Data. Data is not yet posted. This dataset is associated with the following publication: Schmedding, R., M. Ma, Y. Zhang, S. Farrell, H. Pye, Y. Chen, C. Wang, Q. Rasool, S.H. Budisulistiorini, A. Ault, J. Surratt, and W. Vizuete. α-Pinene-Derived organic coatings on acidic sulfate aerosol impacts secondary organic aerosol formation from isoprene in a box model. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, USA, 213: 456-462, (2019).

EPA did not generate data as part of this work. This dataset is not publicly accessible because: I personally did not generate any new data in this study. It can be accessed through the following means: Via contact with corresponding author. Format: This study was led by the University of North Carolina at Chapel Hill and they plan to distribute through Mendeley Data. Data is not yet posted. This dataset is associated with the following publication: Schmedding, R., M. Ma, Y. Zhang, S. Farrell, H. Pye, Y. Chen, C. Wang, Q. Rasool, S.H. Budisulistiorini, A. Ault, J. Surratt, and W. Vizuete. α-Pinene-Derived organic coatings on acidic sulfate aerosol impacts secondary organic aerosol formation from isoprene in a box model. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, USA, 213: 456-462, (2019).

Indoor chamber and filter extraction experimental details, E-AIM II model results, RPLC(−) and HILIC/(−)ESI-HR-QTOF instrument conditions and oxidation product spectra, SOA yield comparison at varying acidity, HR-TOF-CIMS instrument conditions and oxidation product spectra, proposed MS fragmentation of selected oxidation tracers, SOA yield calculations. This dataset is associated with the following publication: Fruenheim, M., J. Offenberg, Z. Zhang, J.D. Surratt, and A. Gold. Chemical Composition of Secondary Organic Aerosol Formed from the Oxidation of Semivolatile Isoprene Epoxydiol Isomerization Products. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 58(51): 22571-22582, (2024).

Oxidation of the monoterpene Δ3-carene (C10H16) is a potentially important and under-studied source of atmospheric secondary organic aerosol (SOA). We present chamber-based measurements of the speciated gas and particle phases during photochemical oxidation of Δ3-carene. We find evidence of highly oxidized organic molecules (HOM) in the gas phase and relatively low volatility SOA dominated by C7-C10 species. We then use computational methods to develop the first stages of a Δ3-carene photochemical oxidation mechanism and explain some of our measured compositions. We find that alkoxy bond scission of the cyclohexyl ring likely leads to efficient HOM formation, in line with previous studies. We also find a surprising role for the abstraction of primary hydrogens from methyl groups, which has been calculated to be rapid in the α-pinene system, and suggest more research is required to determine if this is more general to other systems and a feature of autoxidation. This work develops a more comprehensive view of Δ3-carene photochemical oxidation products via measurements and lays out a suggested mechanism of oxidation via computationally derived rate coefficients. This dataset is not publicly accessible because: Non-EPA data. It can be accessed through the following means: Please contact Joel Thornton at: thornton@atmos.uw.edu. Format: text files. This dataset is associated with the following publication: D'Ambro, E., N. Hyttinen, K. Møller, S. Iyer, R. Otkjær, D. Bell, J. Liu, F. Lopez-Hilfiker, S. Schobesberger, J. Shilling, A. Zelenyuk, H. Kjaergaard, J. Thornton, and T. Kurten. Pathways to highly oxidized products in the Δ3-Carene + OH system. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 56(4): 2213-2224, (2022).