Atmospheric Chemistry and Physics最新文献

{"title":"The role of the QBO for tropical high-cloud variability in CMIP6 models and observations","authors":"Aleena M. Jaison,Paulo Ceppi,Sarah Wilson Kemsley","doi":"10.5194/acp-26-14403-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14403-2026","url":null,"abstract":"The Quasi-Biennial Oscillation (QBO) is a dominant mode of stratospheric zonal wind variability. Observations indicate that the QBO influences tropical phenomena such as convection, precipitation, and the Madden–Julian Oscillation, yet climate models often fail to capture these relationships. This study examines the QBO's impact on high clouds, in particular tropical tropopause layer clouds, in CMIP6 historical simulations and CALIPSO observations. Building on recent findings that identified relevant cloud-controlling factors (CCFs) for high clouds, we apply CCF analysis to assess QBO-driven changes in high-cloud amount and interpret these changes in terms of contributions from controlling factors. Our results confirm that the QBO westerly (QBOW) phase is associated with reduced tropical mean high-cloud cover. CMIP6 models successfully capture the reduction in tropical high clouds associated with QBOW, but with a weaker magnitude and strong inter-model spread. Among the analysed CCFs, upper-tropospheric temperature, static stability at 150 hPa and relative humidity contribute most to this reduction in observations, and to the model bias. The substantial model bias and spread suggest that better constraints on high-cloud sensitivity to upper-tropospheric thermodynamics are needed to improve simulated QBO-related cloud responses. This framework may also help assess cloud responses to climate change, including the role of greenhouse gas–driven stratospheric cooling.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"11 1","pages":"14403-14416"},"PeriodicalIF":6.3,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrostatics and Collision dynamics of ice and anthropogenic smoke particles in the mesosphere/lower thermosphere","authors":"Trinesh Sana,Sanjay K. Mishra,Ingrid Mann","doi":"10.5194/acp-26-14385-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14385-2026","url":null,"abstract":"The increase in satellite launches raises the anthropogenic influx of various elements into the Mesosphere and Lower Thermosphere (MLT), comparable to the natural influx caused by meteoric ablation. This study investigates the electrostatic interactions between nano-meter-sized ice particles and remnants of space debris using a classical electrostatic framework. Aside from the Coulomb interaction, the attractive force between two particles at short distances, arising from polarization, is taken into account. Collision outcomes, the effective velocity regime for collisions, and the subsequent aggregation probability are estimated. Aggregation is limited to a specific range of collision velocities between minimum and maximum values. This range varies depending on factors such as particle size, mass density, and dielectric constant. For most particles, the velocity range of aggregation is from a few m s −1 to several tens of m s −1 , where smaller particles may need significantly higher velocities to form stable aggregates. When considering the collisions of particles in thermal motion, it is found that Al 2 O 3 (due to its greater abundance) and TiO 2 (due to its higher dielectric constant), both originating from anthropogenic sources, may dominate in the formation of ice-anthropogenic particle aggregates. In the MLT region, the formation of stable aggregates from the collision of ice with particles from space debris, which one may denote as anthropogenic smoke particles (ASPs), is similar to that from collisions with meteoric smoke particles (MSPs).","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"12 1","pages":"14385-14401"},"PeriodicalIF":6.3,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of the summertime diurnal precipitation cycle over three representative regions of China to convective trigger and closure treatments in a single-column model","authors":"Xiaocong Wang,Yanjie Liu,Yimin Liu","doi":"10.5194/acp-26-14471-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14471-2026","url":null,"abstract":"Using a single-column model, we investigate how trigger and closure treatments in ZM, TDK, and UNICON convection schemes affect the diurnal cycle of precipitation over China. For late-afternoon rainfall, TDK and ZM schemes with standard CAPE closure simulate precipitation peaks around noon, substantially earlier than observed. The UNICON scheme, with cold-pool feedback deactivated, also produces a noontime peak. For nocturnal rainfall, all schemes spuriously produce a noontime peak, in stark contrast to the observed nocturnal maximum. These behaviors are closely related to closure assumptions and the resulting cloud-base mass flux, which is primarily governed by CAPE in ZM and TDK, and responds more directly to surface fluxes in UNICON. By accounting for the imbalance between deep convection and boundary-layer production through specific modifications: adopting the dCAPE trigger in ZM, activating cold-pool feedback in UNICON, and applying the non-equilibrium closure in TDK, the simulated afternoon precipitation is delayed and in better agreement with observations. In addition, allowing elevated convection in ZM and UNICON improves nocturnal rainfall. The improved diurnal cycle is also evident in the diabatic heating fields. All modifications lead to a delayed and more pronounced upward-tilting heating structure as a result of the suppression of early-afternoon convection, with ZM and TDK extending to higher altitudes, while both intensified and extended in UNICON. These changes alleviate the upper-level cold bias in TDK and ZM. In UNICON, however, the overly strong convection reverses the upper-tropospheric bias from cold to warm with stronger magnitude, thereby worsening the bias.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"13 1","pages":"14471-14485"},"PeriodicalIF":6.3,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simultaneous measurements of gas- and aerosol-phase water-soluble organic nitrogen in the winter urban atmosphere of Chengdu, China","authors":"Kaitao Chen,Zheng Li,Rui Li,Luyao Chen,Rongjie Li,Binyu Xiao,Shaojun Lv,Can Wu,Rui Li,Junke Zhang,Gehui Wang","doi":"10.5194/acp-26-14329-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14329-2026","url":null,"abstract":"Partitioning gaseous water-soluble organic nitrogen (WSON) to the aerosol phase is a major formation pathway of atmospheric secondary organic aerosols (SOA). However, the factors influencing this WSON partitioning process remain unclear. We conducted simultaneous wintertime measurements of WSON in both gas and aerosol phases at an urban site in Chengdu (CD), located in the Sichuan Basin (SCB), China, to investigate the concentration, gas-particle partitioning processes, and driven factors of WSON. The average concentration of particulate WSON (2.3±1.4µgNm-3) was about twice that of gaseous WSON (1.2±0.9µgNm-3) and increased significantly as PM 2.5 increased. In winter, WSON readily partitions into the particle phase (FWSON=0.70±0.14), partitioning into the organic phase under warm, dry conditions and into aerosol liquid water under cold, humid conditions, with higher F WSON in the latter. Amines (methylamine, MA; dimethylamine, DMA) were predominantly present in the gas phase but exhibited enhanced partitioning into the particle phase during the PM 2.5 polluted periods. Amines preferentially partitioned into aerosol liquid water throughout the entire campaign, stably existing as amine-sulfate or amine-nitrate salts in PM 2.5 . The influence of aerosol liquid water content (ALWC) on the partitioning behavior of both WSON and amines was substantially greater than that of temperature ( T ), relative humidity (RH), and aerosol acidity (pH), as further confirmed by thermodynamic modeling with S-curve analysis. Furthermore, NH 4 NO 3 was identified as the primary contributor to ALWC, suggesting that controlling NO x and NH 3 emissions is crucial for reducing ALWC and subsequent WSON formation.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"27 1","pages":"14329-14343"},"PeriodicalIF":6.3,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cloud vertical structure across China from a national Ka-band cloud radar network: thermodynamic, dynamical, and land-surface controls","authors":"Hui Xu,Jianping Guo,Jianbo Deng,Rongfang Yang,Deli Meng,Zhen Zhang,Ning Li,Yuping Sun,Shuairu Jiang,Tianmeng Chen,Juan Chen,Liping Zeng,Yongshui Zhou,Bing Tong","doi":"10.5194/acp-26-14303-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14303-2026","url":null,"abstract":"Cloud vertical structure (CVS) plays a fundamental role in regulating the Earth's radiation budget and hydrological cycle, yet its representation in numerical weather prediction and climate models remains highly uncertain, largely due to limited high-resolution regional observations. Using a newly established national network of 80 Ka-band millimeter-wave cloud radars (MMCRs), here we present a high-spatiotemporal-resolution (vertical resolution of 30 m, temporal resolution of 1 min) characterization of CVS across China based on one year (2024) of observations, and quantify its thermodynamic, dynamical, and land-surface controls. Cloud boundaries are retrieved using an improved algorithm that integrates height-dependent radar sensitivity with variance-based clutter suppression. Results show that the national annual mean cloud occurrence frequency is 56.7 ± 7.2 %, dominated by single-layer clouds (34.7 ± 4.0 %), followed by two-layer (14.7 ± 3.2 %) and multi-layer clouds (7.1 ± 2.4 %). Spatially, single-layer clouds prevail over arid northwestern China, whereas multi-layer clouds are more frequent in humid southeastern region. Cloud base height (CBH) exhibits strong seasonality (summer > spring > autumn > winter), with notably low CBH over the Tibetan Plateau. Diurnally, summer clouds show a pronounced afternoon peak between 3 and 9 km, while winter clouds remain largely below 3 km and peak near sunrise. Thermodynamic conditions exert the primary control on CVS. Higher 2 m specific humidity promotes deeper cloud development and raises cloud top height (CTH), whereas enhanced lower-tropospheric stability suppresses vertical cloud growth and lowers both CBH and CTH. Dynamical forcing further modulates cloud structure: stronger vertical wind shear (VWS) generally inhibits vertical cloud development, reducing CBH, CTH and cloud thickness, while moderate VWS can enhance organization under unstable conditions. Joint dependence analyses reveal that moisture, stability, and shear act in a coupled manner, with moisture being the dominant driver and stability and shear serving as strong regulators. In addition, land-surface characteristics significantly influence CBH, especially for afternoon single-layer low clouds, which exhibit a mean CBH is 21.7 % higher than the all-hour low clouds, with the strongest enhancement over evergreen broadleaf forests (+41.7  % ). These findings provide the first observationally constrained, national-scale assessment of CVS based on this radar network, offering quantitative benchmarks for evaluating and improving cloud parameterizations in weather and climate models.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"160 1","pages":"14303-14327"},"PeriodicalIF":6.3,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synoptic and regional-scale meteorological controls of stratus altitude in the Namib Desert","authors":"Viola Hipler,Hendrik Andersen,Robert Spirig,Roland Vogt,Stuart Piketh,Bianca Adler,Jan Cermak","doi":"10.5194/acp-26-14367-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14367-2026","url":null,"abstract":"In the Namib Desert, fog is an essential water source and occurs when and where advected marine stratus clouds intersect with the land surface. However, the meteorological controls of the cloud base height are still insufficiently understood. This study aims to develop a basic understanding of the processes that influence the stratus altitude and, by extension, the spatial occurrence of fog. We combine satellite and in situ observations with large-scale meteorological data from reanalysis data (ERA5) to compare fog events to lifted stratus at the coast (low-cloud events). In fog situations, the marine boundary layer is shallower by up to 130 m along the entire coastline than in low-cloud situations. This is found to be related to the large-scale high-pressure systems. Fog situations exhibit a weaker Atlantic High but elevated continental pressure. The weaker Atlantic High is connected to less pronounced near-surface winds along the coastline, less cold advection, and heat fluxes upstream of the study region, leading to the shallower marine boundary layer. In parallel, higher continental pressures on fog days facilitate the formation of stronger nocturnal katabatic winds which can mix with, undercut or block the advected cloudy marine air. An alternative mechanism is highlighted in a case study of an off-season fog event, where a ridging high produces hot and dry subsiding easterly air masses which lower and intensify the inversion from above. To assess the predictive power of the continental and Atlantic high-pressure systems and the regional pressure pattern, a logistic regression is trained with three corresponding features. The classification outperformed a climatological baseline by ≈10 %, suggesting that the features contain relevant process information. The results improve our understanding of the processes that determine the seasonal and day-to-day variability of fog versus elevated low-cloud occurrence in the Namib.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"237 1","pages":"14367-14384"},"PeriodicalIF":6.3,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing lightning NO\u0000 \u0000 x\u0000 \u0000 production in the Ebro Valley with meteosat 12 LI and LMA observations","authors":"Francisco J. Pérez-Invernón,Francisco J. Gordillo-Vázquez,Oscar van der Velde,Joan Montanyà,Jesús Alberto López Trujillo,Nicolau Pineda,Diego Loyola,Sora Seo,Christoph Knote,Alexandre O. Fierro,Heidi Huntrieser","doi":"10.5194/acp-26-14277-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14277-2026","url":null,"abstract":"Lightning is one of the main sources of NO x in the Earth's atmosphere, yet there is considerable variability in NO x production during thunderstorms. In this study, we combined optical lightning data from the Meteosat Third Generation (MTG) Lightning Imaging (LI) instrument, which provides information on the occurrence rate and physical characteristics of lightning flashes, measurements from an extended Lightning Mapping Array (LMA) consisting of 24 sensors, lightning measurements from the Lightning Location System (LLS) of the Meteorological Service of Catalonia (MSC), and TROPOspheric Monitoring Instrument (TROPOMI) cloud and NO 2 research products to investigate lightning NO x emissions in the Ebro Valley (Spain). WRF-Chem simulations were used to calculate the necessary air mass factors and to subtract the NO x not produced by lightning from the TROPOMI measurements, allowing a more accurate estimation of lightning-induced NO x . We found positive relationships between lightning-produced NO x per flash and several lightning properties, including flash channel length, radiance, footprint, duration and the length of the optical continuous signal detected from space. These results highlight the importance of combining detailed lightning observations with atmospheric modeling to quantify NO x emissions from thunderstorms.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"160 1","pages":"14277-14301"},"PeriodicalIF":6.3,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-monotonic response of net dust deposition kinetics to low wind speeds","authors":"Ruochen Jia,Chaoqun Ba,Chao Zhang,Wennong Kuang,Yuan Liu,Zhigang Wang,Fang Liu,Zhiming Xin,Yuting Liu,Qun Ma,Lu Zong,Wei Liang,Jianqiang Qian,Zhimin Liu","doi":"10.5194/acp-26-14245-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14245-2026","url":null,"abstract":"Dry deposition is a major sink for mineral dust, yet its behavior under weak winds remains poorly constrained and is often parameterized monotonically with wind speed. Here we quantify size-resolved dust net accumulation kinetics in a closed-circuit recirculating wind tunnel using a two-stage protocol (brief high-wind loading followed by low-wind deposition at 0, 2, 4, and 6 m s −1 ). Cumulative retained-mass time series were measured with an array of collection trays, with the initial suspended dust loading recorded by an online concentration monitor. Particle sizes were characterized by laser diffraction and grouped into six diameter-threshold classes (PM 2.5 –PM 63 ). A first-order kinetic model described the temporal accumulation dynamics and yielded a fitted asymptotic retained mass ( a ), effective net-accumulation rate coefficient ( k ), characteristic time scale (τ=1/k), and initial net accumulation flux ( J 0 = a k ). The observed  J 0 was highest at 2 m s −1 for PM 2.5 –PM 30 , and 4 m s −1 for PM 40 and PM 63 , while  J 0 declined markedly at 6 m s −1 for the lower diameter thresholds. Quadratic fits across the four wind-speed levels suggest a potential maximum near 2–3 m s −1 for PM 2.5 –PM 40 . These measurements quantify the size-dependent response of effective surface retention to low wind speeds and provide benchmark behavior for coupled deposition, retention, and re-entrainment parameterizations.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"22 1","pages":"14245-14258"},"PeriodicalIF":6.3,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Warm-sector heavy rainfall over the eastern China plains: identification, characteristics, and precursor dynamic signals","authors":"Weilong Deng,Jianping Guo,Ning Li,Zhen Zhang,Yifei Wang,Yi Yang","doi":"10.5194/acp-26-14259-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14259-2026","url":null,"abstract":"Warm-sector heavy rainfall (WSHR) poses forecasting challenges, while its contribution to regional heavy rainfall and short-term precursors remain poorly quantified. Drawing on 2021–2025 warm-season (June–September) observations from 493 surface rain gauges, ERA5 reanalysis, and a radar wind profiler (RWP) mesonet across the eastern China plains, we build an objective identification framework integrating automated front detection, warm-sector mask, and station-specific 99th-percentile hourly rainfall thresholds to separate WSHR from other heavy rain events. We detect 477 station-based WSHR events alongside 6002 other heavy rainfall events. WSHR is spatially scattered, peaks in July–August, and preferentially begins at 20:00–03:00 Beijing Time (BJT). Accounting for merely 5 %–10 % of annual heavy rainfall occurrences, WSHR has shorter durations yet comparable median rainfall accumulations and heavier extreme rainfall tails. Among the 297 stations recording at least one WSHR event, the mean station-level contribution of WSHR to heavy-rainfall accumulation is 13.8 %, with a maximum of 48.1 %. Composite ERA5 fields show that WSHR initiates within an 850 hPa moist tongue of high pseudo-equivalent potential temperature south of the front, superimposed on strengthening low-level moisture flux convergence. RWP composites of 62 WSHR events show increasing low-level jet (LLJ) occurrence and enhanced low-level ascent shortly before rainfall onset. Comparison with 271 warm-sector non-heavy rainfall events indicates a more pronounced late increase in LLJ occurrence and a stronger upper tail of ascent speeds at 1–2 km in WSHR, although the distributions overlap substantially. These observations identify candidate kinematic indicators whose event-level predictive skill remains to be evaluated.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"22 1","pages":"14259-14275"},"PeriodicalIF":6.3,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertical distribution of pollution trapped by wintertime surface inversions in Fairbanks, Alaska, during the ALPACA experiment","authors":"Jochen Stutz,Jonas Kuhn,Sol Cooperdock,Sarah Johnson,Fangzhou Guo,James H. Flynn,Meeta Cesler-Maloney,William R. Simpson","doi":"10.5194/acp-26-14345-2026","DOIUrl":"https://doi.org/10.5194/acp-26-14345-2026","url":null,"abstract":"Air pollution in cold wintertime urban areas is a ubiquitous problem. Surface temperature inversions under low wind conditions and surface emissions lead to the formation of a shallow polluted surface layer (PSL). The presence of this PSL is well documented, but its height, the rates of exchange with the background atmosphere, and the interplay between vertical mixing and chemistry remain poorly quantified. Here we provide quantitative insights into this coupled chemistry-transport system using observations and modeling of vertical pollutant profiles. Long-path Differential Optical Absorption Spectroscopy of vertical trace gas profiles during the 2022 Alaskan Layered Pollution and Chemical Analysis (ALPACA) experiment in Fairbanks, Alaska, quantitatively track the frequent establishment of PSLs with heights of 20–40 m, which sometimes persist for several days. PSL trace gas mixing ratios often plateau at levels of up to 35 ppb SO 2 , 60 ppb NO 2 , 2.5 ppb HONO, 7 ppb HCHO, and low ozone as a result of surface emissions, gas-phase chemistry, and ineffective mixing with the background atmosphere. Parameterizing vertical mixing with observed surface temperature gradients and wind speed in the PACT-1D chemistry and transport model leads to excellent agreement of modeled and measured trace gas profiles. The PACT-1D transport scheme determines the residence time of pollutants within the PSL to be 1–4 h, confirming the strong influence of atmospheric mixing on the composition of sustained PSL events. Altitude-dependent ozone and NO x chemistry highlight the strong coupling between mixing and chemistry, which must be considered to quantify pollutant concentrations accurately in shallow PSLs.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"55 1","pages":"14345-14365"},"PeriodicalIF":6.3,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}