Atmospheric chemistry and physics

Abstract. Ice cloud microphysical properties, such as phase, shape, size and density, introduce significant uncertainties and biases that affect our understanding of how clouds influence weather and climate. The upcoming spaceborne sub-millimeter radiometers are expected to help in reducing the ice microphysics induced uncertainties in observations. Yet our knowledge about ice microphysics in thi…

Abstract. During the passage of tropical cyclone (TC) Batsirai (2022), the mountainous regions of Réunion Island and the eastern part of Madagascar experienced devastating floods. TC Batsirai passed north of Réunion Island (minimum distance of ~210 km) before making landfall along the eastern coast of Madagascar. Using the Meso-NH model at 2 km resolution, we conducted a control simulation with r…

Abstract. On the night of 13 June 2013, the University of Science and Technology of China (USTC) sodium lidar observed multiple sporadic sodium layers (SSLs) and enhanced sodium patterns (ESPs) over Hefei, China (31.8°N, 117.3°E). These structures appeared at different times, collectively spanning nearly the entire night, and exhibited distinct vertical motions and horizontal propagation behavior…

Abstract. Anthropogenic sulphate aerosol is a primary forcing agent in the historical period, and its exact impact on North Atlantic SST variability remains an open question. A set of novel, idealised, single-forcing experiments was performed to isolate the physical processes. The medium-resolution (60 km atmosphere, 0.25° ocean) and low-resolution (135 km atmosphere, 1° ocean) of the HadGEM3-GC3…

Abstract. Accurately modeling the cloud condensation nuclei (CCN) budget is a key factor in reducing uncertainty in aerosol–cloud interactions in Earth system models. Wet deposition – the removal of particles by precipitation – is a major CCN sink, but rainfall can also trigger a replenishment phase via the formation and growth of new particles, partially offsetting losses. However, the ability o…

Abstract. The 2022 Hunga eruption injected unprecedented quantities of water vapor into the stratosphere, alongside modest amounts of aerosol precursors. There remain uncertainties regarding the extent to which it influenced the stratospheric ozone layer. We address this using a multi-model ensemble of chemistry-climate model simulations, assessing the impacts of Hunga-induced perturbations in bo…

Abstract. Realistic cloud droplet number concentrations (Nd) are critical for simulating the Earth's radiative budget, yet remain challenging to represent in global models. One reason is that aerosol optical depth (AOD), commonly used for aerosol validation and assimilation, only weakly constrains aerosol number concentrations relevant for cloud formation. We introduce a representation of aerosol…

Abstract. Ice supersaturated regions (ISSRs) are air masses in the upper troposphere and lower stratosphere (UTLS) where saturation ratio over ice (Si) exceeds one, i.e. regions with enhanced water vapor concentrations. These are potential formation regions of cirrus clouds and contrails. While the impact of cloud free regions of enhanced water vapor on the planetary radiation balance is small to…

Abstract. Organosulfur compounds (OrgSs), especially organosulfates (OSs), are ubiquitous aerosol components. However, the spatial, seasonal, and day-night variations of OrgS formation in polluted atmospheres remain poorly understood. Here, we monitored particulate OrgSs at an urban site and a suburban site in Shanghai and investigated their molecular composition and potential formation pathways …

Abstract. Reactive nitrogen (Nr) species such as particulate ammonium (pNH4+) and nitrate (pNO3-) are critical drivers of air pollution and ecosystem health, yet their transformation in mountain forests remains poorly characterized. We performed a one-week field campaign in a subtropical mountain forest at Xitou, Taiwan, using size-segregated aerosol sampling, stable isotopic techniques, and Baye…

Abstract. A large discrepancy of at least 10 Gg yr−1 exists between reported emissions of the potent greenhouse gas HFC-23 (CHF3, trifluoromethane) and emissions derived from atmospheric measurements. In-atmosphere production of HFC-23 from the breakdown of fluorinated source gases such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs) contributes to this gap, but only a conservative upp…

Abstract. Aerosol mixing state strongly influences how particles interact with clouds, radiation, and atmospheric chemistry, but it remains difficult to quantify from routine observations. The aerosol mixing state index (χ) typically requires detailed single-particle composition data, available only from particle-resolved models or advanced measurements. Yuan and Zhao (2023) proposed estimating χ…

Abstract. Tropospheric NO2 over the Tibetan Plateau (TP) reflects the combined influence of local emissions and long-range transport. We characterize the spatiotemporal variability of tropospheric NO2 columns, surface concentrations, and transport boundary fluxes during 2005–2024 by integrating OMI and TROPOMI satellite data, ground-based observations, and flux diagnostics based on a closed-loop …

Abstract. Some major volcanic eruptions, such as the one of Mt. Pinatubo in 1991, can inject large amounts of sulfur dioxide (SO2) into the stratosphere, leading to a volcanic aerosol cloud. This dense aerosol cloud induces a radiative heating of the stratosphere, causing ozone and water vapour changes, thereby altering middle atmospheric dynamics and chemistry. The scale of these impacts for var…

Abstract. Marine Cloud Brightening (MCB) is a proposed method of Solar Radiation Modification (SRM). MCB proposes the injection of sea salt aerosols into marine clouds to enhance their reflectivity aiming to counteract greenhouse gas (GHG) driven warming. Modelling suggests that the climate effect of MCB depends on the location of deployments, with some regional MCB resulting in potentially undes…

Abstract. Persistent contrails are a major contributor to aviation-induced non-CO2 climate forcing, yet the extent to which their development depends on background cloud properties remains unclear. In this study, we aim to investigate persistent contrail development in various cloudy backgrounds. We use the high-resolution ICON-LEM model with a horizontal resolution of 156 m. Eight distinct ice-c…

Abstract. Triple oxygen isotopes are powerful tracers of hydrological processes, yet their variability in atmospheric water vapor and the underlying controls remain poorly understood. We present a one-year record of triple oxygen and hydrogen isotopes of atmospheric water vapor (δ18OV, d-excessV, 17O-excessV) measured below, within and above a downy oak forest canopy at the AnaEE platform O3HP in…

Abstract. The aroma compound ethyl butyrate (EB) and its methylated derivatives ethyl 2-methylbutyrate (EM), ethyl isovalerate (EI), and isopropyl butyrate (IB) are present in many consumer products. To evaluate the environmental and health impacts of these volatile organic compounds, a detailed understanding of their gas-phase photochemical reactivity is required. Here, we performed pulsed laser…

Abstract. Tropospheric ozone (O3) is a significant anthropogenic climate forcer with uncertain distribution in the Southern Hemisphere due to sparse observations. This study analyzes 28 years of in situ ozone, methane, carbon monoxide, and meteorological data at Tololo (30.17° S, 70.80° W, 2154 m a.s.l.), Chile, integrating reanalysis and atmospheric chemistry modeling. Here we identify a rising …

Abstract. Acute short-term exposure to extremely high PM2.5 levels posed serious health risks. Human culture-based festival activities can significantly alter emission patterns, often leading to sharp yet understudied fluctuations in air quality. The Chinese Spring Festival (CSF), marked by large-scale family reunions and widespread use of fireworks, raises air pollution concerns. Commonly, this …