ACP - recent papers

1. Western Arctic wintertime mixed-phase clouds: Observed modulation by sea ice conditions, long-term variabilities and trends
   Western Arctic wintertime mixed-phase clouds: Observed modulation by sea ice conditions, long-term variabilities and trends Pablo Saavedra Garfias and Heike Kalesse-Los Atmos. Chem. Phys., 26, 14843–14865, https://doi.org/10.5194/acp-26-14843-2026, 2026 Arctic low level mixed-phase clouds were analysed from 14 years of wintertime observations from the North Slope of Alaska. We found that Arctic cloud physical properties are in correlation with changes in upwind sea ice. The cloud liquid and ice water content increases as sea ice decreases, although not at the same magnitude. Moreover, we uncovered that cloud properties have oscillation properties along the years that resemble climate indicators like El Niño Southern Oscillation among others.
2. From direct emission factors to inverse and indirect impact factors of road traffic: influence of emerging and unregulated pollutants
   From direct emission factors to inverse and indirect impact factors of road traffic: influence of emerging and unregulated pollutants Lauri K. Savolainen, Teemu Lepistö, Heidi Hellén, Henna Lintusaari, Milja Jäppi, Jarkko V. Niemi, Kimmo Teinilä, Minna Aurela, Markus Lampimäki, Anu Kousa, Janne Lampilahti, Katrianne Lehtipalo, Tuukka Petäjä, Miikka Dal Maso, Hanna E. Manninen, Hilkka Timonen, and Topi Rönkkö Atmos. Chem. Phys., 26, 14823–14841, https://doi.org/10.5194/acp-26-14823-2026, 2026 The study investigates vehicle fleet emissions of road traffic. Despite technological advances, road traffic is still an important pollution source in urban areas, especially when considering unregulated, but health-relevant, emerging pollutants. We report fuel consumption normalized vehicle fleet emission factors for various regulated and unregulated air pollutants. Also, we show that road traffic has inverse and indirect effects on urban aerosol which are not generally well understood.
3. Assessing the consistency of XCO2 products from DQ-1 ACDL and passive satellites using a unified comparison framework
   Assessing the consistency of XCO2 products from DQ-1 ACDL and passive satellites using a unified comparison framework Yike Wang, Ge Han, Hongyuan Zhang, Yiyang Huang, Kangjie Zhou, and Wei Gong Atmos. Chem. Phys., 26, 14793–14822, https://doi.org/10.5194/acp-26-14793-2026, 2026 This study establishes a unified framework to assess the consistency of DQ-1 (Da Qi-1) ACDL (Aerosol and Carbon Dioxide Lidar) XCO2 with passive satellite products while considering sampling and column-definition differences. DQ-1 agrees well with TCCON (Total Carbon Column Observing Network) and shows consistent spatial patterns with OCO-2, OCO-3 (Orbiting Carbon Observatory), GOSAT, and GOSAT-2 (Greenhouse gases Observing SATellite) over selected regions. It provides complementary XCO2 observations where passive measurements are limited, including nighttime and high latitudes, supporting future joint carbon monitoring and inversion studies.
4. From prototypical regimes to observed complex dynamics and CO2 transport in the Amazonian nocturnal boundary layer
   From prototypical regimes to observed complex dynamics and CO2 transport in the Amazonian nocturnal boundary layer Anna C. Huitema, Vincent S. de Feiter, Raquel González-Armas, Oscar K. Hartogensis, Hella van Asperen, Cleo Q. Dias-Júnior, and Jordi Vilà-Guerau de Arellano Atmos. Chem. Phys., 26, 14725–14747, https://doi.org/10.5194/acp-26-14725-2026, 2026 We studied how well idealised models of the nighttime boundary layer capture observed variability above the Amazon rainforest, using observations from the CloudRoots-Amazon22 campaign. The observations indicate large nocturnal variability, caused by non-stationary processes and interactions between the within- and above-canopy atmosphere. Common weather and climate models often miss this variability, highlighting the need to represent the complex forest-atmosphere interactions better.   
5. Can radon help to improve methane emission estimates? Results from a dual-tracer inversion
   Can radon help to improve methane emission estimates? Results from a dual-tracer inversion Fabian Maier, Christian Rödenbeck, Ute Karstens, Frank-Thomas Koch, Maksym Gachkivskyi, Andrew Smerald, and Christoph Gerbig Atmos. Chem. Phys., 26, 14699–14723, https://doi.org/10.5194/acp-26-14699-2026, 2026 Transport model errors represent a major source of uncertainty in greenhouse gas flux estimates derived from inverse modelling, yet they remain challenging to quantify. In our study, we leverage the similarities in the atmospheric transport of methane (CH4) and radon (222Rn) by performing a dual-tracer CH4-222Rn inversion over Europe, with the goal of enhancing the reliability of CH4 flux estimates. We discuss the benefits and limitations of this dual-tracer approach.