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The Fire Modeling Intercomparison Project (FireMIP) for CMIP7
Fire is a global phenomenon and a key Earth system process. Extreme fire events have increased in recent years, and fire frequency and intensity are projected to rise across most regions and biomes, posing substantial challenges for ecosystems, the carbon cycle, and society. The Fire Model Intercomparison Project (FireMIP), launched in 2014, has advanced global fire modeling in Dynamic Global Vegetation Models (DGVMs) and improved understanding of fire's local and direct drivers and its local impacts on vegetation and land carbon budgets through land offline simulations (i.e., uncoupled from the atmosphere). We now bring FireMIP into Coupled Model Intercomparison Project Phase 7 (CMIP7) to: (1) evaluate fire simulations in state-of-the-art fully coupled Earth system models (ESMs); (2) assess fire regime changes in the past, present, and future, and identify their primary natural and anthropogenic forcings and causal pathways within the Earth system, including the associated uncertainties; and (3) quantify the impacts of fires and fire changes on climate, ecosystems, and society across Earth system components, regions, and timescales, and elucidate the underlying mechanisms. FireMIP in CMIP7 will advance the fire and fire-related modeling in fully coupled ESMs, and provide a quantitative, comprehensive, and process-based understanding of fire's role in the Earth system by using models that incorporate critical climate feedbacks and CMIP7 multi-model, multi-initial-condition, and multi-scenario ensemble. This protocol paper presents the motivation, scientific questions, experimental design and rationale, model inputs and outputs, and recommended analysis framework for FireMIP in CMIP7, providing guidance to Earth system modeling teams conducting simulations and informing communities studying fire, climate change, and climate solutions.
2026
2026
This study provides a short-term, dry-weather multi-compartment assessment of microplastic (MP) contamination in the Choghakhor Wetland, a vital freshwater ecosystem in western Iran. We quantified MPs in air, subsurface water, the surface water microlayer (SML), and sediments and developed a first-order mass-balance framework to clarify transport and fate. The SML showed much higher MP concentrations than the subsurface water when converted to volumetric units, while method-specific SML estimates varied among approaches (4.4–13.8 MP m⁻² using a glass tube; 196–982 MP m⁻² using a sieve; and 130–1754 MP m⁻² using filter paper). Subsurface water contained 0.083–1.5 MP L⁻¹, and the two sediment samples contained 60–400 MP kg⁻¹. Atmospheric deposition during the monitored intervals reached 2363 MP m⁻² h⁻¹. Flux analysis indicated that dry-weather influx exceeded observed outflux by more than three orders of magnitude. Using the conservative combined-outlet scenario, the wetland residence time was at least 168 days, whereas a water-only outlet scenario yielded ∼344 days. FLEXPART suggested that road dust dominated modeled source contributions, with smaller agricultural and soil-related contributions, although site-specific attribution remains model-based. These findings identify wetlands as important sinks and reservoirs of MPs, while emphasizing that the present results represent a dry-weather baseline rather than seasonal or annual conditions.
2026
Global mapping of city-level economic growth decoupling from fossil fuels
Cities seek to generate economic prosperity while reducing their dependence on fossil fuel combustion, yet tracking such progress at the city level remains challenging because of the limited and inconsistent emissions and economic data. Here we introduce an objective, globally consistent framework to measure decoupling between fossil fuel use and economic growth, either through reduced fuel use or shifts toward cleaner/more efficient combustion, proxied by tropospheric nitrogen dioxide columns combined with second-level administrative gross domestic product per capita based on purchasing power parity data. Analysing 5,435 cities globally over 2019–2024, we identify significant trends for 2,475 cities and classify them into 4 decoupling states. We find that 80% of these cities, mainly located in China, Europe and North America, enjoy relative decoupling, whereas 16%, mainly located in India and the Middle East, experience fossil fuel-dependent growth. Beyond these patterns, the described scalable satellite-based methodology can be revisited regularly to monitor city-level green growth and support urban policy effectiveness.
2026
Plastic pellet spills are a major source of microplastic pollution, and pellets are found on beaches worldwide. However, the potential environmental impacts of these spills remain poorly understood. In December 2023, approximately 25,000 kg of polyethylene pellets containing high concentrations of the additive Tinuvin UV-622 were spilled during a shipping accident off the northern coast of Portugal. Pellets collected from an affected beach located in Galicia, Spain, along with solvent extracts and aqueous leachates, were subjected to both target and nontarget chemical analyses and tested in a battery of toxicity assays including a green microalga (Raphidocelis subcapitata), a marine copepod (Apocyclops royi), a fish model (Danio rerio), and a human cell line. Chemical screening identified on the order of 50 chemical substances in addition to Tinuvin UV-622, including a range of known plastic additives and nonintentionally added substances (NIAS). Toxicity assays revealed significant growth inhibition and stress-induced cell aggregation in R. subcapitata and acute toxicity causing immobilization in copepods, which could have potential implications in the environment via the disruption of primary producers and food web dynamics. In contrast, zebrafish embryos showed no significant developmental effects, while human cells exhibited modest, time-dependent reductions in viability. Our findings underscore the complex chemical burden associated with pellet spills and stress the need for policies and regulations to prevent them, reinforcing the importance of applying the precautionary principle in managing the environmental risks linked to plastic pellet production, transport, and accidental release.
2026
Understanding new particle formation (NPF) and the fate of nanoparticles is crucial because of their close links to air quality, cloud formation, and climate. These effects vary spatially and temporally owing to diverse aerosol sources and their relatively short atmospheric lifetime. Here, we present a comprehensive analysis of long-term trends in NPF-associated nucleation-mode particles and cloud condensation nuclei (CCN) concentrations across diverse observation environments using quality-controlled particle number size distribution (PNSD) and CCN data from 37 sites, primarily from Global Atmosphere Watch (GAW) stations. We identify declining decadal trends in both NPF occurrences and nucleated particle concentrations across most site types, with the strongest declines in urban areas. We observe simultaneous reductions in both CCN concentrations and nucleation-mode particles, suggesting that newly formed particles are a potential source of CCN. This, in turn, suggests that cloud microphysical properties and radiative effects can be indirectly influenced through aerosol–cloud interactions that modify cloud droplet formation. These findings indicate that decreasing anthropogenic emissions could influence the climate forcing potential of aerosol–cloud interactions, with important implications for future climate projections.
2026
Aerosol-Cloud Interactions: Overcoming a Barrier to Projecting Near-Term Climate Evolution and Risk
Aerosol-cloud interactions (ACI) are a major source of uncertainty in climate science, critically affecting our ability to project near-term climate evolution and assess societal risks. These interactions influence effective radiative forcing, cloud dynamics, and precipitation patterns, yet remain insufficiently constrained due to limitations in observations, modeling, and process understanding. This uncertainty hampers robust policy advice across multiple domains—from estimating remaining carbon budgets and climate sensitivity, to anticipating regional extreme events and evaluating climate interventions such as solar radiation modification. In many cases, the influence of ACI is either underappreciated or excluded from decision-making frameworks due to its complexity and lack of quantification. This perspective outlines a path forward to overcome these barriers by leveraging emerging opportunities in satellite remote sensing, ground-based and airborne observations, high-resolution climate modeling, and machine learning. We identify key areas where rapid progress is feasible, including improved retrievals of cloud microphysical properties, better representation of natural aerosols in a warming world, and enhanced integration of observational and modeling communities. Even as anthropogenic aerosol and its impacts on clouds is reducing owing to emissions controls, addressing ACI uncertainties remains essential for refining climate projections, supporting effective mitigation and adaptation strategies, and delivering actionable science to policymakers in a rapidly changing climate system.
2026
Indoor environments have shown to be a major source of human exposure of polychlorinated alkanes (PCAs), yet information on their distribution across indoor matrices and associated exposure pathways remains limited. PCAs, the main components in chlorinated paraffin mixtures, are widely used as flame retardants and plastic additives in numerous indoor consumer products and materials. This study quantified PCAs in paired indoor dust and indoor organic films (IOFs) from homes, offices, schools and gym sports halls (n = 41) in Sweden and assess their contribution to human exposure. Mean PCA concentrations in indoor dust were 7.3, 43.2, and 14.6 μg g−1 for ∑PCAs-C10–13, ∑PCAs-C14–17, and ∑PCAs-C18–30, respectively, while corresponding concentrations in IOFs were 38.2, 312, and 123 ng m−2. PCAs-C14–17 dominated both matrices, but IOFs showed an enrichment tendency towards longer-chain, higher-KOA PCAs, reflecting the less frequent cleaning and longer-term PCA accumulation in IOFs. IOF concentrations were particularly elevated in schools, and PCA variation across sites was influenced by differences in ventilation practices and building age. Dermal uptake was the dominant exposure pathway for children, with substantially estimated doses from IOFs, while adults show comparable dust dermal and dust ingestion exposures. PCA transformation products formed through hydroxylation, hydrolysis, and sulfation were also tentatively detected in both matrices. These findings highlight the importance of jointly assessing dust and IOFs to better characterize multipathway exposure to the diverse PCA mixture in indoor environments.
2026
Tracking the Path to Cleaner Cities using Global Urban NO₂ Monitoring from Space
Tracking air pollution is essential for evaluating the effectiveness of urban air-quality and emission-control policies and their impact on public health. Unlike previous satellite-based urban NO₂ studies that typically rely on linear trends, aggregated data, and limited meteorological correction, we use high-resolution TROPOMI observations with an AirGAM framework to estimate meteorology-adjusted, non-linear NO₂ TVCD trends across 5,435 cities worldwide (2019–2024). Daily satellite observations, together with ERA5 meteorology, are used to remove weather and seasonal effects so that trends primarily reflect changes in emissions. 1,400 cities had significant trends, with 79% showing declines, indicating an overall global drop in urban NO₂ TVCD. East Asia, particularly China (99% of cities with significant trend), and Europe (95%) led the global reductions. Cities in the USA with significant trends (n = 14) also experienced a decline. NO₂ TVCD levels increased most sharply in the cities of the Middle East, Central, and South Asia. The most populated examples are Tehran (3.1% yr-1 [95% CI: 0.7–5.5]) and Cairo (1.4% yr-1 [0.1–2.6]).
2026
A pan-European spatial inventory of agricultural land degradation
Agricultural land degradation is a contemporary reality that increasingly threatens food security and socio-economic stability in Europe and worldwide. Monitoring and controlling this environmental problem are complicated missions, considering that land degradation generally occurs as multiple processes in agricultural environments, which have not yet been thoroughly investigated as an integrated multi-process and multi-scale inventory in Europe. Here we developed a detailed multi-scale (continental to sub-regional) inventory of 12 key agricultural land degradation pathways in Europe, including water erosion, wind erosion, soil organic carbon loss, soil salinization, soil acidification, soil compaction, soil nutrient imbalances, soil pollution via pesticides, soil pollution via heavy metals, vegetation degradation, groundwater decline, and aridity. Using various and (generally) high-resolution geospatial datasets of land degradative pathways, which were mapped at critical levels and statistically explored as a spatial footprint at various territorial levels, we highlighted a complex geographical pattern of agricultural degradation across Europe. Our findings revealed that continental agricultural environments are between 1 and 52 % affected by critical levels of individual degradative processes. Essentially, our results highlighted that soil pollution via pesticides (which impacts 52 % of Europe's evaluated agricultural area), soil nutrient imbalances (39 %), soil pollution via heavy metals (31 %), aridity (25 %), water erosion (15 %), and soil compaction (15 %) are the largest threats to European agriculture. Furthermore, using a Land Multi-degradation Index that integrates the critical conditions of all degradative processes, we emphasized that 31 % of pan-European agricultural landscapes are impacted by significant multi-degradation (lands simultaneously affected by at least three co-occurring processes). This general picture of agricultural degradation becomes however increasingly heterogeneous towards the more detailed (national to sub-regional) territorial levels, according to the multiple maps (52) and statistics provided in this unprecedented integrated inventory, which has the potential to support various land degradation-related policies in Europe.
2026
Safeguarding drinking water in north-western europe by modelling the fate of amines from CO2capture
The European Union (EU) net-zero emission target for 2050 requires large-scale deployment of carbon capture and storage (CCS). Amine-based CO2 capture (CC) is the most mature CC technology but may lead to the spread of nitrosamines (NSAs) and nitramines (NAs) in the nearby surroundings. These are carcinogenic compounds that can persist in water resources. Hence, EU's ambition towards carbon neutrality might pose risk of drinking water contamination as well as ecosystem and agricultural crops pollution. We compiled a dataset of planned CCS projects in the Franco-Danish corridor, Europe's future CCS hub, where most capacity will be located by 2030, with at least 40% based on amine technology. Spatial analysis indicates that up to 10.2 million inhabitants, large Natura 2000 reserves, and extensive crop areas may be impacted by NA and NSA deposition, often in regions already under severe water stress. Biogeochemical modelling shows that surface waters with short residence times are highly sensitive to deposition rates, whereas groundwater concentrations depend strongly on the interplay between NA and NSA half-lives and travel times, creating greater uncertainty in aquifers, especially small systems with limited dilution. In both cases, MEA is the most environmentally friendly when emission abatement measures are limited to water wash, compared to piperazine and other emerging solvents. Main findings highlight the need for regional-scale modelling and harmonized regulation to safeguard drinking water, ecosystems, and food security as CCS deployment expands.
2026
Fluoropolymers are widely used across sectors, but their production is associated with emissions of perfluoroalkyl and polyfluoroalkyl substances (PFASs), which are mobile, persistent, and toxic. In this work, we compiled a global inventory of fluoropolymer production plants (FPPs) and assembled PFAS concentration measurements for various media in their vicinity. We identified 52 currently operating FPPs across 11 countries and 41 cities. For 12 FPPs, in 12 different cities, there are peer-reviewed site-specific PFAS measurements specifically attributed to the FPP. At these 12 sites, at least 236 individual PFASs have been detected across multiple environmental media, including surface water, groundwater, air, dust, soils, sediments, plants, animals, and humans, with reported detections at distances of up to approximately 150 km from FPPs. Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl ether carboxylic acids (PFECAs) were most frequently measured, often at concentrations two to three orders of magnitude higher than those measured in regions without nearby FPPs. Using high-resolution population data, we estimate that approximately 14 ± 2 million people (uncertainty reflecting ± 10 km uncertainty in facility locations) live within 10 km of an FPP. These people are potentially affected by FPP-associated contamination, with the largest population shares in China (≈52%), Japan (≈24%), Europe (≈13%), and the United States (≈9%). These regional proportions largely mirror differences in population density and the number of identified production facilities. This inventory reveals the large and complex global scale of PFAS contamination from fluoropolymer production, underscoring the need for expanded systematic monitoring and risk management efforts, including regulation.
2026
Tracing the air–sea exchange of microplastics over the Caspian Sea
The global proliferation of microplastics (MPs) is increasingly recognized as a transboundary environmental issue. At the air–ocean interface, MPs can be emitted via sea spray and transported back to land, while terrestrial MPs can likewise be advected and deposited over the oceans. However, the long-term net exchange of MPs between land and ocean via the atmosphere remains poorly constrained. Here, we investigate coastal atmospheric MPs and their near-surface landward and seaward transport over the southern Caspian Sea. Using a combination of passive air sampling (at seven heights with MWAC collectors) and active sampling (vacuum pump) over periods of 3 days and 2 months, respectively, together with coastal surface sediment samples, we quantified MP concentrations and assessed the influence of meteorological and environmental factors on their distribution. Fibrous MPs dominated all compartments, with airborne concentrations averaging 3.85 MP m−3 and sediment concentrations ranging from 507 to 1476 MP kg−1 (dry weight). Estimated near-surface horizontal fluxes were comparable in magnitude, with a landward influx of ~6566 MP m−2 h−1 and a seaward outflux of ~8039 MP m−2 h−1, indicating broadly balanced coastal transport during the 72 h campaign. To support source attribution, we evaluated co-trapped particulate proxies (sea salt and ash) and combined them with FLEXPART modelling. Trajectory modelling and proxy evidence indicate that most airborne MPs originated from inland sources (e.g., road dust and textile-related fibres), while marine sea-spray contributions were minor during the sampling period. These findings highlight the importance of long-range atmospheric transport in coastal MP pollution and demonstrate how integrating proxy observations with dispersion modelling can help constrain likely source regimes.
2026
Precise estimation of atmospheric pollutant releases is crucial for assessing the impact of environmental accidents. Atmospheric inversion typically relies on a linear model with a source–receptor sensitivity (SRS) matrix, which may contain significant errors or even completely fail to capture the real magnitude of the event. We propose a correction of the SRS matrix formulated as slight shifts in the observation locations, effectively warping the sensitivity field. To constrain these shifts and ensure data-driven corrections, we model them using a Gaussian process prior. This prior not only enforces smoothness and sparsity, but also enables posterior prediction of shifts at previously unseen locations. This key feature provides a mechanism for hyper-parameter tuning: the predicted shift field can be visualized on a map and assessed by an expert. We present a user-friendly framework that combines a Bayesian inversion model with correction and a tuning algorithm based on L-curve-like plots and the maps of predicted shifts. The proposed method is demonstrated on three case studies: the ETEX-I experiment, the 137Cs emissions during the 2020 Chernobyl wildfires, and the 106Ru release in 2017.
2026
Accumulation patterns of polychlorinated alkanes in an Arctic marine food web
Polychlorinated alkanes (PCAs), otherwise known as chlorinated paraffins, are contaminants of emerging Arctic concern where our understanding of their occurrence and trophic transfer in Arctic food webs remains limited. To investigate biomagnification potential of PCAs, we analyzed short-chain PCAs: C10-C13 and medium-chain PCAs-C14-17 in three Arctic species: polar cod (Boreogadus saida), ringed seal (Pusa hispida), and polar bear (Ursus maritimus) and Subarctic capelin (Mallotus villosus) samples collected from the northern Barents Sea in 2017 and 2021. PCAs-C10-13 concentrations were low, but detectable in all species, while PCAs-C14-17 concentrations were mainly below detection limits in the mammals. PCAs did not biomagnify, as the lowest concentrations were found in polar bear (0.7 ng g−1 lw) and the highest in capelin (56.9 ng g−1 lw). The PCA homologue profiles were similar among Arctic species, with PCAs-C10-13 dominating in polar cod and marine mammals, which may suggest a contribution from long-range atmospheric transport.
In contrast, PCAs-C14-17 were most abundant in the Subarctic capelin, likely reflecting a different exposure. Despite differing PCAs-C14-17 concentrations among the two fish species, their PCAs-C14-17 homologue profile was similar, indicating uniform global production trends. Subarctic capelin is increasingly being preyed upon by Arctic predators and may facilitate the biological transport of PCAs-C14-17 into Arctic ecosystems.
These findings suggest that climate-driven shifts in species distribution may have the potential to alter contaminant exposure pathways in Arctic marine food webs.
2026
The ISLAS2020 field campaign during February and March 2020 set out to obtain a unique dataset describing the Arctic water cycle using stable water isotope (SWI) observations. Our observation strategy focused on measuring evaporation, deposition, and precipitation, all of which are commonly sub-grid scale processes in numerical weather and climate models. Uncertain parameterizations for these processes can lead to compensating errors, which can go unnoticed; however, evaporation and precipitation can also be investigated with SWIs, as they are an integrated tracer for processes that atmospheric moisture has undergone. The campaign can be divided into two efforts: a localised field experiment in Ny-Ålesund focused on evaporation and deposition, and a larger precipitation collection network distributed around the Nordic Seas. The Ny-Ålesund field experiment lasted three weeks, from 23 February to 15 March 2020, with temperatures reaching below −30 °C. During these weeks, we obtained near-surface, high-resolution (approx. 20 cm) SWI profiles at two deployment sites. Using a newly developed profiling system, we measured SWI gradients in the lowermost 5 and 2 m over fjord water and snow-covered tundra, respectively. These profiles are complemented by fiber-optic distributed sensing (FODS) columns and ambient conditions from nearby meteorological stations. The FODS columns supply continuous, high-resolution (2 cm or finer) temperature profiles above both locations, whereas the meteorological stations provide information on wind speed and direction. We also made a short deployment to the Zeppelin mountain observatory (472 ma.s.l.) for measurements of the isotopic signal in the free-troposphere. Additionally, numerous water samples from the snowpack in and around Ny-Ålesund were taken, in addition to daily fjord water samples from Kongsfjorden. These samples provide the context for the surface conditions under which profiles were collected. Isotopic connections on the synoptic scale are achieved by linking Ny-Ålesund observations with precipitation sampling at locations across the European Arctic, namely Longyearbyen, Tromsø, Andenes, Ålesund, and Bergen. The resulting dataset provides comprehensive insight into the Arctic hydrological cycle and can facilitate the study of phase change processes and transport of water vapour into and out of the Svalbard region. Datasets from the field campaign are publicly available at the PANGAEA data repository (https://doi.org/10.1594/PANGAEA.971241, Seidl et al., 2024).
2026
Soil degradation in Europe is projected to accelerate under changing land use and climate
Soil degradation threatens food security and environmental sustainability, yet future projections of it are rare. Using projections from 18 global climate models under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) and land-use projections from the Land Use and Climate Across Scales Land Use Change (LUCAS LUC) dataset, we assess future soil vulnerability to degradation by linking a Soil Degradation Proxy (SDP) to climate, land-use, soil characteristics, and socio-economic factors at 7433 observation sites across Europe. We project that by 2071–2100, ~59% of sites may become more vulnerable under the high-emission scenario. Cold forest regions in northern Europe are projected to face increased degradation pressure by ~+0.04SDP. However, some European croplands may improve locally through conversion to secondary lands, reduced human pressures, and natural recovery processes. These regionally specific trends highlight that, while soil degradation remains a major threat, proactive land management can mitigate soil vulnerability under future climate trajectories.
2026
2026
Abstract The International Cooperative Programme on Integrated Monitoring of Air Pollution Effects on Ecosystems (ICP IM) presents a comprehensive long-term dataset of ongoing integrated ecosystem monitoring from European forested catchments. The dataset encompasses measurements from 46 monitoring stations across 14 European countries, with temporal coverage mostly extending from the early 1990s to 2020 (48 sites are currently active). The integrated monitoring approach applies over 20 monitoring subprogrammes to simultaneously measure physical, chemical, and biological properties across multiple ecosystem compartments including atmosphere, precipitation, throughfall, soil water, groundwater, runoff water, soil, vegetation, and biota. All measurements follow standardised protocols detailed in the ICP IM Manual, ensuring data quality and comparability across sites and time periods. The dataset supports research on ecosystem responses to air pollution, climate change impacts, and biogeochemical cycling. Data are available under a Creative Commons By Attribution (CC BY) licence, providing valuable long-term environmental monitoring data for the scientific community.
2026
Circular Economy (CE) principles seek to eliminate hazardous substances and promote the reuse and recycling of plastic products. However, implementing these principles is challenging due to the wide variety of substances used in plastics, their potential health and environmental risks, the complexities of global supply chains, and concerns regarding reappearance of Chemicals of concern (CoCs) in post-recycled plastics (PRP). This study presents a novel approach for identifying CoCs in the waste stream by assessing the potential presence of chemicals in polymers across different industrial sectors and their hazard categories. With the objective of identifying CoCs that are most problematic regarding their reappearance in new products, selected CoCs are classified into four priority groups based on their physicochemical properties and molecular structures, for further risk and regulatory assessment. The first group includes 88 CoCs, that must be avoided in a circular economy, of which 70% are metalloids and 30% are organic additives. The second group comprises 167 CoCs, mainly additives, whose risks depend heavily on their concentration and specific use in products. The third and fourth groups consist of CoCs that are less frequently found in plastic waste and thus associated with relatively lower risks. Overall, this study offers a practical and adaptable tool to support the identification of hazardous substances in plastic waste, helping stakeholders make informed decisions by removing CoCs and promoting the development of safer alternatives for substitutions.
2026
Coastal aerosols are formed through the complex mixing between marine air masses and continental emissions, which originate from both natural and anthropogenic sources. The properties of coastal aerosols are decisive for their interaction with sunlight and their influence on clouds, as well as the potential health implications for the population in these areas. In this study, the aerosol properties and sources at Aarhus Bay, Denmark, were investigated by combining in situ aerosol light scattering and absorption with size distribution measurements and footprint analysis by FLEXPART. Our analysis demonstrates a considerable contribution of anthropogenic aerosols from both fossil fuel combustion and biomass burning, as well as periods with highly scattering aerosols. Furthermore, good agreement was found between in situ and modelled black-carbon data. Combining in situ measurements and FLEXPART analysis further evidenced a major impact of local emissions, as well as a few long-range transport intrusions.
2026
During summer 2023, Greece experienced one of its most severe wildfire seasons in recent decades, with widespread fires across Evros, Rodopi, Attica, the Peloponnese, and several islands. This study investigates the aerosol optical and microphysical properties, as well as the impact on ground-level ultraviolet-B (UVB) radiation over Athens, focusing on two major wildfire episodes (18–21 July and 22–25 August). A synergistic approach was deployed, combining satellite imagery (MODIS), FLEXPART simulations, ground-based remoter sensing, in situ aerosol and radiation measurements. Elevated aerosol optical depths (AOD) up to 1.2, high fine-mode fractions (FMF) (> 0.85), and Ångström exponents (AE) above 1.5 indicated a strong dominance of fine biomass burning aerosols. The Single scattering albedo (SSA) ranged from 0.85 to 0.98, showing enhanced absorption during biomass burning periods and weaker absorption when smoke was mixed with dust. At 320 nm, dust presence resulted in stronger absorption, with SSA below 0.8 for pure dust cases compared to smoke mixtures. Particle linear depolarization ratios (PLDR), varied between 0.03 and 0.20, with higher values (∼ 0.10–0.20) reflecting the presence of non-spherical dust particles, and lower values (∼ 0.03–0.08) indicating spherical smoke particles. Ground-level UVB irradiance decreased by up to 50 % during peak smoke episodes, highlighting strong aerosol radiative impacts. Concurrently, PM10 and PM2.5 concentrations increased to 94 and 49 µg m−3, respectively, while organic aerosols peaked at 22.77 µg m−3, consistent with intense fire activity. FLEXPART simulations confirmed long-range transport of smoke from active fire regions, with additional contributions from regional pollution and Saharan dust.
2026
Physics-Informed Deep Learning for Wind Downscaling over Oslo
Running a numerical weather model such as WRF at kilometre or sub-kilometre grid spacing over a regional domain is computationally expensive. We present physics-informed deeplearning models that ingest a single 9km WRF wind field and simultaneously predict two finer-scale wind fields at 3 km and 1 km resolution via dual decoder heads. Four representative architectures are benchmarked-Deep Residual U-Net (DeepRU), DEVINE, a bespoke 3-D Transformer, and a Fourier Neural Operator (FNO)-each trained with divergence-free, vorticity, and Navier-Stokes residual constraints plus Charbonnier and gradient perceptual losses. We train and validate our models on the city of Oslo for the year 2018. DeepRU achieves R2=0.94 (RMSE =0.050) at 3km and R2=0.89(RMSE=0.065) at 1 km. DEVINE, Transformer 3-D, and FNO yield 3 km scores of 0.91−0.93, with 1km scores lower by 0.02−0.08, illustrating the increased difficulty of finer-scale reconstruction. Physicsinformed losses improve all models compared to MSE-only baselines, and the residual architecture (DeepRU) remains most effective for this dual-scale task.
2025
Abstract Trifluoroacetic acid (TFA) is a persistent pollutant with potential long‐term effects on the environment and on health. Recent studies using ice core records report large increases (up to tenfold) in Arctic TFA deposition since the 1970s, and trends suggest long‐lived chlorofluorocarbon (CFC) replacements may be a major source. Here, we use a chemical transport model to examine the global TFA budget arising from CFC replacements–hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs)–and inhalation anesthetics. Global TFA deposition from these sources increased ∼3.5‐fold from 6.8 (5.9–7.6) Gg/yr in 2000 to 21.8 (18.6–25.0) Gg/yr in 2022, with cumulative deposition reaching 335.5 Gg. We find HCFC‐123, HCFC‐124, and HFC‐134a account for most modeled TFA production and that long‐lived CFC replacements account for virtually all of the observed Arctic deposition trend. At lower latitudes, our analysis supports the recent emergence of hydrofluoroolefins (HFOs) as a TFA source. We conclude that increased TFA monitoring is required.
2026