Northwest China, situated in an arid and semi-arid climate region; air quality issues in this area have received less attention compared to other Chinese metropolitan clusters.  This research identify a significant shift towards the coupling PM_2.5 and O₃ relationships over the past decade in northwest China, highlighting the great importance of urban terpenes and aromatic oxidation in secondary organic aerosol formation. 

Organic aerosols undergo changes when exposed to oxidants like ozone or UV (ultraviolet) light. This study looks at how both aging processes affect particle properties, using trans-aconitic acid as a proxy for secondary organic aerosols. We found that exposure to UV light and ozone causes mass loss and changes viscosity significantly, up to 4 orders of magnitude. This suggests that aged particles may take much longer than untreated particles to equilibrate under dry conditions.

Ice clouds in the Arctic and mid-latitudes were investigated using in situ aircraft observations combining single-particle imaging with simultaneous light-scattering measurements. The joint characterisation of ice particle size, shape, and optical response shows that these clouds reflect substantially more solar radiation than is typically represented in models. The observations provide an empirical basis for improving the physical realism of ice cloud optical properties in climate models.

Climate models rely on uncertain adjustable parameters. We tested millions of combinations of these inputs to see how well the model matches real-world data. We found that no single set of inputs can match several observations at the same time, which suggests that the issue lies in the model itself. We developed a method to detect these conflicts and trace them back trace them to their source. The aim is to help modellers target improvements that reduce uncertainty in climate projections.

Planetary waves are important for driving large scale circulations. We observed planetary waves in a ground-based data set spanning more than 30 years. The waves can be assigned to expected waves due to their periods. The wave activity is strongest in winter for waves with periods longer than 20 days and shows maxima around equinoxes for periods below 20 d. The long-term behaviour shows a quasi-20 year oscillation of the wave activity with respect to the magnitude of the wave amplitudes.

This study examines air pollution in Beijing-Tianjin-Hebei and the Yangtze River Delta from 2015 to 2022. PM_2.5 (particulate matter) decreased by 9.1-31.4 μg/m³ and PM₁₀ by 9.8–42.9 μg/m³. Weather factors like humidity, air pressure, and rainfall influenced pollution, with tailored solutions needed for different regions.

We create a hybrid ecosystem-level carbon flux model using both eddy-covariance observations and observations of the atmospheric mole fraction of CO₂ at three tall-tower observatories. Our study uses an atmospheric transport model (STILT) to connect the atmospheric signal to the ecosystem-level model. We show that this inclusion of atmospheric information meaningfully improves the model's representation of the interannual variability of the global net flux of CO₂.

This study reports multi-year (2022–2024) measurements of 76 volatile organic compounds (VOCs) at a rural site in Cyprus. Oxygenated VOCs were the most abundant and showed strong daytime increases due to sunlight-driven chemistry.  Air-mass analysis showed that transport from Middle East strongly influenced aromatic VOC levels. Climate–chemistry modeling underestimated most VOCs, highlighting gaps in current emission and chemical processes.

Surface ozone pollution in East Asia is among the highest in the world and has risen steadily over the past two decades. Using aircraft observations and a global 3-D chemical transport model, we show that ozone in the lower atmosphere in East Asia has risen in part due to intensified transport from the upper atmosphere. This rising natural background limits the effectiveness of local pollution controls, with major implications for air quality policy.

This study compares two sets of stratospheric aerosol injection (SAI) experiments using the same modeling framework, differing only in their aerosol microphysical schemes. Results show that these two schemes can yield substantially different aerosol burdens, radiative changes, and impacts when simulating the same injection scenarios. These findings suggest that more sophisticated aerosol models may be necessary to accurately assess the efficacy, side effects, and climate impacts of SAI.

Mixed-phase clouds play a key role in Earth’s climate but remain poorly represented in climate models. We improved their representation in the EC-Earth model by introducing an aerosol-sensitive scheme for ice formation and a machine-learning approach for secondary ice production. These advances produce more realistic cloud properties and radiative effects, highlighting that both processes are essential for reliable climate projections.