Gasoline- and diesel-fueled engines are ubiquitous sources of air pollution in urban environments. They emit both primary particulate matter and precursor gases that react to form secondary particulate matter in the atmosphere. In this work, we use experimentally derived inputs and parameterizations to predict concentrations and properties of organic aerosol (OA) from mobile sources in southern California using a three-dimensional chemical transport model, the Community Multiscale Air Quality Model (CMAQ). The updated model includes secondary organic aerosol (SOA) formation from unspeciated intermediate volatility organic compounds (IVOC). Compared to the treatment of OA in the traditional version of CMAQ, which is commonly used for regulatory applications, the updated model did not significantly alter the predicted OA mass concentrations but it did substantially improve predictions of OA sources and composition (e.g., POA-SOA split), and ambient IVOC concentrations. The updated model, despite substantial differences in emissions and chemistry, performs similar to a recently released research version of CMAQ. Mobile sources are predicted to contribute about 30–40 % of the OA in southern California (half of which is SOA), making mobile sources the single largest source contributor to OA in southern California. The remainder of the OA is attributed to non-mobile anthropogenic sources (e.g., cooking, biomass burning) with biogenic sources contributing less than 5 % to the total OA. Gasoline sources are predicted to contribute about thirteen times more OA than diesel sources; this difference is driven by differences in SOA production. Model predictions highlight the need to better constrain multi-generational oxidation reactions in chemical transport models. This dataset is associated with the following publication: Jathar, S., M. Woody, H. Pye, K. Baker, and A. Robinson. Chemical transport model simulations of organic aerosol in southern California: model evaluation and gasoline and diesel source contributions. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 17: 4305-4318, (2017).

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).

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).

Dataset contains information displayed in figures 1-4 and abstract/table of contents figure. This dataset is associated with the following publication: Budisulistiorini, S., A. Nenes, A. Carlton, J. Surratt, V.F. McNeill, and H. Pye. Simulating Aqueous-Phase Isoprene-Epoxydiol (IEPOX) Secondary Organic Aerosol Production During the 2013 Southern Oxidant and Aerosol Study (SOAS). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 51(9): 5026-5034, (2017).

Dataset contains information displayed in figures 1-4 and abstract/table of contents figure. This dataset is associated with the following publication: Budisulistiorini, S., A. Nenes, A. Carlton, J. Surratt, V.F. McNeill, and H. Pye. Simulating Aqueous-Phase Isoprene-Epoxydiol (IEPOX) Secondary Organic Aerosol Production During the 2013 Southern Oxidant and Aerosol Study (SOAS). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 51(9): 5026-5034, (2017).

Links point to the NOAA data archive of observational data and the supplement of the article which this data supports. No model data was uploaded due to its size. All updates to CMAQ used in this work are available in the public release of CMAQv5.1 (available through github or the CMAS Center). This dataset is associated with the following publication: Pye , H., D. Luecken , L. Xu, C.M. Boyd, N.L. Ng, K. Baker , B.R. Ayres, J. Bash , K. Baumann, W.P.L. Carter, E. Edgerton, J.L. Fry, B. Hutzell , D. Schwede , and P.B. Shepson. Modeling the current and future role of particulate organic nitrates in the southeastern United States. Environmental Science & Technology Letters. American Chemical Society, Washington, DC, USA, 49(24): 14195-14203, (2015).

Several models were used to describe the partitioning of ammonia, water, and organic compounds between the gas and particle phases for conditions in the southeastern US during summer 2013. Existing equilibrium models and frameworks were found to be sufficient, although additional improvements in terms of estimating pure-species vapor pressures are needed. Thermodynamic model predictions were consistent, to first order, with a molar ratio of ammonium to sulfate of approximately 1.6 to 1.8 (ratio of ammonium to 2  ×  sulfate, RN∕2S  ≈  0.8 to 0.9) with approximately 70 % of total ammonia and ammonium (NHx) in the particle. Southeastern Aerosol Research and Characterization Network (SEARCH) gas and aerosol and Southern Oxidant and Aerosol Study (SOAS) Monitor for AeRosols and Gases in Ambient air (MARGA) aerosol measurements were consistent with these conditions. CMAQv5.2 regional chemical transport model predictions did not reflect these conditions due to a factor of 3 overestimate of the nonvolatile cations. In addition, gas-phase ammonia was overestimated in the CMAQ model leading to an even lower fraction of total ammonia in the particle. Chemical Speciation Network (CSN) and aerosol mass spectrometer (AMS) measurements indicated less ammonium per sulfate than SEARCH and MARGA measurements and were inconsistent with thermodynamic model predictions. Organic compounds were predicted to be present to some extent in the same phase as inorganic constituents, modifying their activity and resulting in a decrease in [H+]air (H+ in µg m−3 air), increase in ammonia partitioning to the gas phase, and increase in pH compared to complete organic vs. inorganic liquid–liquid phase separation. In addition, accounting for nonideal mixing modified the pH such that a fully interactive inorganic–organic system had a pH roughly 0.7 units higher than predicted using traditional methods (pH  =  1.5 vs. 0.7). Particle-phase interactions of organic and inorganic compounds were found to increase partitioning towards the particle phase (vs. gas phase) for highly oxygenated (O : C  ≥  0.6) compounds including several isoprene-derived tracers as well as levoglucosan but decrease particle-phase partitioning for low O : C, monoterpene-derived species. This dataset is associated with the following publication: Pye, H., W. Appel, H. Foroutan, A. Zuend, J. Fry, G. Isaacman-VanWertz , N.L. Ng, A. Goldstein, S. Capps, and L. Xu. Coupling of organic and inorganic aerosol systems and the effect on gas–particle partitioning in the southeastern US. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 18: 357-370, (2018).

The volatile nature of biomass burning organics may complicate the evolution of organics in laboratory smog-chamber experiments and in ambient plumes. We simulate the evolution of organic mass (including gas and particles) in the chamber experiments using the TwO-Moment Aerosol Sectional (TOMAS) microphysics model combined with a secondary organic aerosol (SOA) production matrix. We estimate the effect of vapor wall loss by turning off the vapor wall loss, and also added Gaussian dispersion to our aerosol-microphysical model to SOA formation under different ambient-plume conditions. A detailed description of model setup and results can be found in Bian et al. 2017. The data publication here contains simulation datasets generated using the TOMAS microphysics model combined with a secondary organic aerosol (SOA) production matrix. Datasets are organized according to the figures in Bian et al. 2017 and include 1) chemistry-only simulation data; 2) data generated using the TOMAS model combined with particle and vapor wall-loss algorithms and a SOA production matrix with varying parameters; and 3) simulation data generated using the TOMAS model assuming the plume volume follows the Gaussian dispersion. Each ASCII dataset contains the time series of individual vapors and particles that were distributed in 36 size bins from 3 nanometers to 10 micrometers.

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

Data set contains CMAQ model output for Look Rock, Tennessee and Centreville, Alabama during summer 2013. This dataset is associated with the following publication: Liu, J., L. Russell, G. Ruggeri, S. Takahama, M. Claflin, P. Ziemann, H. Pye, B. Murphy, L. Xu, N. Ng, K. McKinney, S. Hapsari Budisulistiorini, T. Bertram, A. Nenes, and J. Surratt. Regional Similarities and NOx‐Related Increases in Biogenic Secondary Organic Aerosol in Summertime Southeastern United States. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. American Geophysical Union, Washington, DC, USA, 123(18): 10,620-10,636, (2018).