Widespread reduction of ozone extremes in storylines of future climate

By constructing storylines of future climate with fixed anthropogenic emissions, we quantify how temperature and humidity changes affect ozone and associated mortality. Here, we show that locally, vegetation and photochemistry often act in concert to amplify ozone pollution extremes, while increased humidity in the free troposphere tends to suppress background ozone levels.

Influence of nitrogen oxides and volatile organic compounds emission changes on tropospheric ozone variability, trends and radiative effect

Satellites and model simulations show enhancement in tropospheric ozone, which is highly impacted by human-produced nitrous oxides compared to volatile organic compounds. The increased amount of ozone enhances ozone radiative forcing. The ozone enhancement and associated radiative forcing are the highest over South and East Asia. The emissions of nitrous oxides show a higher influence on shifting ozone photochemical regimes than volatile organic compounds.

Optimized step size control within the Rosenbrock solvers for stiff chemical ordinary differential equation systems in KPP version 2.2.3_rs4

Model simulations are essential for understanding the interactions between atmospheric composition and weather. However, models including chemistry are very slow. Hence, any computation speedup of such models is important for understanding the role of atmospheric chemistry within the Earth system. In this study we analyzed and optimized the time step for chemistry calculations. Our results show that atmospheric models could be run notably faster without any loss in accuracy.

Global ground-based tropospheric ozone measurements: reference data and individual site trends (2000–2022) from the TOAR-II/HEGIFTOM project

Tropospheric ozone is an important greenhouse gas and is an air pollutant. The time variability of tropospheric ozone is mainly driven by anthropogenic emissions. In this paper, we study the distribution and time variability of ozone from harmonized ground-based observations from five different measurement techniques. Our findings provide clear standard references for atmospheric models and evolving tropospheric ozone satellite data for the 2000–2022 period.

The legacy of the U.S. Clean Air Act at a crossroads

Chronic and acute exposure to elevated concentrations of ambient fine particulate matter represents a significant health risk. Here, we evaluate the avoided air pollution due to the U.S. Clean Air Act and the potential of the 2016 Paris Agreement to improve air quality in the contiguous U.S. The current weakening of federal agencies in the U.S. will degrade environmental quality, induce sickness and death, and incur costs.

Ozone Production Efficiencies in the Three Largest United States Cities from Airborne Measurements

This study utilizes aircraft-based measurements from a field campaign in summer 2023 to compare the efficiency of ozone production in the three largest US cities.

Semi-volatile oxygenated organics and ammonium chloride increasing sub-micron aerosol hygroscopicity, cloud condensation nuclei and PM1 mass in the Delhi region

Delhi-NCR continues to experience extreme particulate pollution during the winter season, with implications for both health and climate. In this study, we carried out over a month of HR-ToF-AMS-based chemical characterization of sub-micron particles (PM₁) at a background site in Delhi, coupled with CCN measurements, lab experiments, and back-trajectory analysis.

Transported smoke from crop residue burning as the major source of organic aerosol and health risks in northern Indian cities during post-monsoon

As we know, air pollution in India claims nearly 1.5 million lives each year, which has rapidly raised India into the global crosswires of pollution studies. Biomass-burning is a well-known major source, but it is a generic term for several types and thus difficult to implement in policymaking. This study split biomass-burning in Delhi and Kanpur into several contributing source factors - fresh, aged, nitrogen-containing (e.g. wood, cow-dung burning) and agricultural waste-burning. This was achieved by studying the near-molecular-level composition of ambient PM2.5 via offline extractive electrospray ionization (EESI-LTOF) and applying specifically developed data analysis methods to source apportion EESI-TOF data outflows. For Delhi (35%) and Kanpur (66%), biomass-burning was found to be a dominant air pollution source, with crop residue burning accounting for over 50% of PM2.5-attributable mortality in Kanpur and 32% in Delhi.

Gas-Phase Water-Soluble Organic Carbon: CMAQ Model Evaluation in Baltimore County

Prediction of gas-phase water-soluble organic carbon (WSOCg), a precursor for secondary organic aerosol formed through processing in atmospheric waters (aqSOA), has not yet been evaluated in models. We pair the WSOCg predictions from the U.S. EPA’s Community Multiscale Air Quality (CMAQ) model with continuous mist chamber measurements during February–March 2015 and August 2016 in Baltimore County, MD.

Technical note: Water vapour climatologies in the extra-tropical upper troposphere and lower stratosphere derived from a synthesis of passenger and research aircraft measurements

This study introduces a new method to derive adjusted water vapor (H2O) climatologies for the upper tropopshere and lower statosphere (UT/LS) using data from 60 000 flights under the IAGOS program. Biases in the IAGOS water vapour dataset are adjusted, based on the more accurate IAGOS-CARIBIC data. The resulting highly resolved H2O climatologies will contribute to a better understanding of the H2O variability in the UT/LS and its connection to various transport and mixing processes.

Inequality in Hazardous Air Pollutant Emissions and Concentrations Measured Over Los Angeles

Megacity-scale analysis of spatially resolved emissions and concentrations of hazardous air pollutants reveals census tract-scale inequalities, underestimated regulatory emissions, and solvent-related sources impacting low-income and minority communities in urban Los Angeles.

Chemical Composition of Fresh and Aged Asphalt-Related Organic Aerosols: From Ambient Observations to Laboratory Experiments

Asphalt-related emissions are an understudied source of reactive organic compounds with the potential to form organic aerosol (OA). Ambient aerosol mass spectrometry (AMS) measurements of asphalt-related aerosols near a month-long road paving project showed enhanced ambient OA concentrations with a mix of primary and secondary OA signatures.

Kinetics of the reactions of OH with CO, NO, and NO2 and of HO2 with NO2 in air at 1 atm pressure, room temperature, and tropospheric water vapour concentrations

Highly accurate rate coefficients of termolecular reactions between OH and HO2 radicals and reactive nitrogen oxides were measured for conditions in the lower troposphere, providing improved constraints on recommended values. No dependence on water vapour was found except for the HO2+NO2 reaction, which can be explained by an enhanced rate coefficient of the NO2 reaction with the water complex of the HO2 radical.

The impact of photochemical aging on secondary aerosol formation from a marine engine

The emissions from a research ship engine operated with either low sulfur heavy fuel oil (LS-HFO) (FSC = 0.5%) or marine gas oil (MGO) (FSC = 0.01%), were photochemically processed in the oxidation flow reactor “PEAR” to achieve an equivalent photochemical age between 0 and 9 days in the atmosphere.

Machine learning for improvement of upper-tropospheric relative humidity in ERA5 weather model data

Upper-tropospheric relative humidity bias in the ERA5 weather model is corrected by 10 % by an artificial neural network using aircraft in-service humidity data and thermodynamic and dynamical variables. The improved skills of the weather model will advance cirrus research, weather forecasts, and measures for contrail reduction.

2025

2024

2023

2021 - 2022

2015 - 2020

2014 and before