Science Inventory

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Secondary organic aerosol (SOA) from acid-driven reactive uptake of isoprene epoxydiols (IEPOX) contributes up to 40% of organic aerosol (OA) mass in fine particulate matter. Previous work showed substantial conversions of particulate inorganic sulfates to surface-active organosu...

Atmospheric nitrate is a key atmosphere component with implications for air quality, nutrient deposition, and climate.  However, accurately representing atmospheric nitrate concentrations within atmospheric chemistry models is a persistent challenge.  A contributing fac...

The US EPA has developed a set of annual North American anthropogenic and fire emissions data for criteria air pollutants across 18 broad source catagories for 2002 through 2017.  The sixteen new annual emissions inventories were developed using consistent input data and met...

Halogens (chlorine, bromine, and iodine) are known to profoundly influence atmospheric oxidants (hydroxyl radical (OH), hydroperoxyl radical (HO¿), ozone (O¿), and nitrate radical (NO¿)) in the troposphere and sub- sequently affecting air quality. H...

Past work has shown that traffic patterns in the USA and resulting NOx emissions vary by day of week, with NOx emissions typically being higher on weekdays than weekends. This pattern of emissions leads to different levels of ozone on weekends versus weekdays and can be...

We use the Community Multiscale Air Quality (CMAQv5.4) model to examine the potential impact of particulate nitrate (pNO3−) photolysis on air quality over the Northern Hemisphere. We estimate the photolysis frequency of pNO3− by scaling the photolysis frequency o...

Air pollution remains an important contributor to adverse health outcomes in the U.S. Currently, 121 million people, or one third of the U.S. population, live where National Ambient Air Quality Standards are violated.<span style='mso-element:field-begin'> ADDIN EN.CITE <...

Future estimates of atmospheric pollutant concentrations serve as critical information for policy makers to formulate current policy indicators to achieve future targets. Tropospheric burden of O3 is modulated not only by anthropogenic and natural precursor emissions, but also ...

Mobile sources are responsible for a substantial controllable portion of the reactive organic carbon (ROC) emitted to the atmosphere, especially in urban environments of the United States. We update existing methods for calculating mobile source organic particle and vapor emissio...

The design of emission abatement measures to effectivly reduce high ground-level ozone (O3) concentrations in urban areas is very complex. In addition to the strongly non-linear chemistry of this secondary pollutant, precursors can be released by a variety of sources in different...

We analyze hourly PM2.5 (particles with an aerodynamic diameter of ≤2.5 μm) concentrations measured at the U.S. Embassy in Dhaka over the 2016–2021 time period and find that concentrations are seasonally dependent with the highest occurring in wint...

The fourth phase of the Air Quality Model Evaluation International Initiative (AQMEII4) is conducting a diagnostic intercomparison and evaluation of deposition simulated by regional-scale air quality models over North America and Europe. In this study, we analyze annual AQMEII4 s...

Emissions of SO2 resulting from volcanic degassing is one of the important sources that should be considered in the modeling system as it regulates tropospheric SO42- levels not only in the vicinity of the volcano but also through long-range transport that modulates background le...

The air quality of any given location is the result of complex interactions between meteorology and emissions through dynamical, physical, chemical, and photochemical processes. Of the many sources of air pollution, naturally produced emissions such as nitric oxide (NO) from soil...

Wildland fire smoke contains hazardous levels of fine particulate matter (PM2.5), a pollutant shown to adversely effect health. Estimating fire attributable PM2.5 concentrations is key to quantifying the impact on air quality and subsequent health burden. This is a challenging pr...

We examined the impact of dimethylsulfide (DMS) emissions on sulfate concentrations over the continental U.S. by using the Community Multiscale Air Quality (CMAQ) model version 5.4 and performing annual simulations without and with DMS emissions for 2018. DMS emissions enhance su...

This work serves as the second of a two-part study to improve surface PM2.5 forecasts in the continental U.S. through the integrated use of multisatellite aerosol optical depth (AOD) products (MODIS Terra/Aqua and VIIRS DT/DB), multichemical transport model (CTM) (GEOS-Chem,...

Radiological release incidents can potentially contaminate wide areas with radiological materials and decontamination efforts are typically focused on populated areas leaving radionuclides in forested areas for long periods of time. Large wildfires in contaminated forested areas ...

Several locations across the United States in noncompliance with the national standard for ground-level ozone (O3) are thought to have sizable influences from distant extra-regional emission sources or natural stratospheric O3, which complicate the design of local emission contro...

Airborne aerosols reduce surface solar radiation through light scattering and absorption (aerosol direct effects, ADEs), influence regional meteorology, and further affect atmospheric chemical reactions and aerosol concentrations. The inhibition of turbulence and the strengthened...

Volatile chemical products (VCPs) are a significant source of reactive organic carbon emissions in the United States with a substantial fraction (>20% by mass) serving as secondary organic aerosol (SOA) precursors. Here, we incorporate a new nationwide VCP inventory into the C...

Optimal use of Hierarchical Bayesian Model (HBM)-assembled aerosol optical depth (AOD)-PM2.5 fused surfaces in epidemiologic studies requires homogeneous temporal and spatial fused surfaces. No analytical method is available to evaluate spatial heterogeneity. The temporal ca...

A new dynamical core, known as the Finite-Volume Cubed-Sphere (FV3) and developed at both NASA and NOAA, is used in NOAA's Global Forecast System (GFS) and in limited-area models for regional weather and air quality applications. NOAA has also upgraded the operational FV3GFS to v...

Landsat-based land cover database for the conterminous United States. These data are foundational for ORD projects EnviroAtlas and StreamCat/LakeCat and several other EPA projects include annual GHG emissions reported to UNFCCC, Recovery Potential (OW), Healthy watersheds (OW), w...

3D-grid-based chemical transport models, such as the Community Multiscale Air Quality (CMAQ) modeling system, have been widely used for predicting concentrations of ambient air pollutants. However, typical horizontal resolutions of nationwide CMAQ simulations (12 × 12 km2) ...