Atmospheric Chemistry and Physics最新文献

{"title":"Global estimates of ambient reactive nitrogen components during 2000–2100 based on the multi-stage model","authors":"Rui Li, Yining Gao, Lijia Zhang, Yubing Shen, Tianzhao Xu, Wenwen Sun, Gehui Wang","doi":"10.5194/acp-24-7623-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7623-2024","url":null,"abstract":"Abstract. High contents of reactive nitrogen components aggravate air pollution and could also impact ecosystem structures and functioning across the terrestrial–aquatic–marine continuum. However, the long-term historical trends and future predictions of reactive nitrogen components at the global scale still remain highly uncertain. In our study, field observations, satellite products, model outputs, and many other covariates were integrated into the multi-stage machine-learning model to capture the global patterns of reactive nitrogen components during 2000–2019. In order to decrease the estimate uncertainties in the future scenarios, the constructed reactive nitrogen component dataset for the historical period was utilised as the constraint to calibrate the CMIP6 dataset in four scenarios. The results suggested that the cross-validation (CV) R2 values of four species showed satisfying performance (R2>0.55). The concentrations of estimated reactive nitrogen components in China experienced persistent increases during 2000–2013, while they suffered drastic decreases from 2013, except for NH3. This might be associated with the impact of clean-air policies. However, in Europe and the United States, these compounds have remained relatively stable since 2000. In the future scenarios, SSP3-7.0 (traditional-energy scenario) and SSP1-2.6 (carbon neutrality scenario) showed the highest and lowest reactive nitrogen component concentrations, respectively. Although the reactive nitrogen concentrations in some heavy-pollution scenarios (SSP3-7.0) also experienced decreases during 2020–2100, SSP1-2.6 and SSP2-4.5 (middle-emission scenario) still showed more rapidly decreasing trends. Our results emphasise the need for carbon neutrality pathways to reduce global atmospheric N pollution.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"25 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553311","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":"The marinada fall wind in the eastern Ebro sub-basin: physical mechanisms and role of the sea, orography and irrigation","authors":"Tanguy Lunel, Maria Antonia Jimenez, Joan Cuxart, Daniel Martinez-Villagrasa, Aaron Boone, Patrick Le Moigne","doi":"10.5194/acp-24-7637-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7637-2024","url":null,"abstract":"Abstract. During the warm months of the year in Catalonia, the marine air overcomes the coastal mountain range and reaches the eastern Ebro sub-basin. This phenomenon is called marinada and has recently been thoroughly characterized for the first time by Jiménez et al. (2023), based on surface climatological data. However, the main physical mechanisms involved in its arrival and propagation remain to be discovered. This study aims to understand how the marinada is formed and how it interacts with the already developed atmospheric boundary layer. Surface and atmospheric observations are used in combination with the coupled surface–atmosphere model Meso-NH to reveal the mechanisms at play. It is shown that the marinada is generated by the advection of a cool marine air mass over the Catalan Pre-coastal Range by the action of the sea breeze and the upslope wind. This marine air mass then flows into the Ebro basin, creating what is known as the marinada. The characteristics and dynamics of the marinada allow it to be classified as a fall wind. It is also shown that the arrival, propagation and decay of the marinada is strongly dependent on the larger-scale weather situation: westerlies or thermal low. The current study provides a consistent framework for understanding the marinada, paving the way for better modeling and prediction of the phenomenon.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"40 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553348","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":"How atmospheric CO2 can inform us on annual and decadal shifts in the biospheric carbon uptake period","authors":"Theertha Kariyathan, Ana Bastos, Markus Reichstein, Wouter Peters, Julia Marshall","doi":"10.5194/egusphere-2024-1382","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1382","url":null,"abstract":"<strong>Abstract.</strong> The carbon uptake period (CUP) refers to the time of each year during which the rate of photosynthetic uptake surpasses that of respiration in the terrestrial biosphere, resulting in a net absorption of CO₂ from the atmosphere to the land. Since climate drivers influence both photosynthesis and respiration, the CUP offers valuable insights into how the terrestrial biosphere responds to climate variations and affects the carbon budget. Several studies have assessed large-scale changes in CUP based on seasonal metrics from CO₂ mole fraction measurements. However, an in-depth understanding of the sensitivity of the CUP as derived from the CO₂ mole fraction data (CUP_MR) to actual changes in the CUP of the net ecosystem exchange (CUP_NEE) is missing. In this study, we specifically assess the impact of (i) atmospheric transport (ii) inter-annual variability in CUP_NEE (iii) regional contribution to the signals that integrate at different background sites where CO₂ dry air mole fraction measurements are made. We conducted idealized simulations where we imposed known changes (∆) to the CUP_NEE in the Northern Hemisphere to test the effect of the aforementioned factors in CUP_MR metrics at ten Northern Hemisphere sites. Our analysis indicates a significant damping of changes in the simulated ∆CUP_MR due to the integration of signals with varying CUP_NEE timing across regions. CUP_MR at well-studied sites such as Mauna Loa, Barrow, and Alert showed only 50 % of the applied ∆CUP_NEE under non interannually-varying atmospheric transport conditions. Further, our synthetic analyses conclude that interannual variability (IAV) in atmospheric transport accounts for a significant part of the changes in the observed signals. However, even after separating the contribution of transport IAV, the estimates of surface changes in CUP by previous studies are not likely to provide an accurate magnitude of the actual changes occurring over the surface. The observed signal experiences significant damping as the atmosphere averages out non-synchronous signals from various regions.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"55 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553349","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":"Measurement Report: Changes of ammonia emissions since the 18th century in south-eastern Europe inferred from an Elbrus (Caucasus, Russia) ice core record","authors":"Michel Legrand, Mstislav Vorobyev, Daria Bokuchava, Stanislav Kutuzov, Andreas Plach, Andreas Stohl, Alexandra Khairedinova, Vladimir Mikhalenko, Maria Vinogradova, Sabine Eckhardt, Susanne Preunkert","doi":"10.5194/egusphere-2024-1381","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1381","url":null,"abstract":"<strong>Abstract.</strong> To investigate the historical levels of atmospheric ammonia (NH₃) pollution in south-eastern Europe, a 182 m long ice core was extracted from Mount Elbrus in the Caucasus, Russia. This ice core contains a record of ammonium (NH₄⁺) levels from ~1750 CE (Common Era) to 2009 CE. The NH₄⁺ ice core record indicates a 3.5-fold increase of annual concentrations from 34 ± 7 ng g^-1 (~1750–1830) to 117 ± 23 ng g^-1 over the recent decades (1980–2009). The increase remained moderate until 1950 CE (mean concentration of 49 ± 14 ng g^-1 over the 1830–1950 period), and then accelerated to reach a maximum close to 120 ng g^-1in 1989. This ice core trend is compared to estimated past anthropogenic NH₃ emissions in Europe by using state-of-the-art atmospheric transport modeling of submicron aerosols (FLEXPART model driven with 0.5° x 0.5° ERA5 reanalysis data). It is shown that in summer, when both vertical atmospheric mixing and agricultural NH₃ emissions are strengthened, the NH₄⁺ ice core trend is in good agreement with the course of estimated NH₃ emissions from south-eastern Europe since ~1750 with a main contribution from south European Russia, Turkey, Georgia, and Ukraine. Examination of Mount Elbrus ice deposited over the second half of the 18^th century when agricultural activities were less than 10% of those during the 1990s, suggest a pre-1750 annual NH₄⁺ice concentration related to natural emissions of 25 ng g^-1. This pre-1750 natural level mainly related to natural soil emissions represents ~20% of the 1980–2009 NH₄⁺level, a level mainly related to current agricultural emissions that almost completely outweigh biogenic emissions from natural soils.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"25 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553429","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":"Measurement report: Size-resolved secondary organic aerosol formation modulated by aerosol water uptake in wintertime haze","authors":"Jing Duan, Ru-Jin Huang, Ying Wang, Wei Xu, Haobin Zhong, Chunshui Lin, Wei Huang, Yifang Gu, Jurgita Ovadnevaite, Darius Ceburnis, Colin O'Dowd","doi":"10.5194/acp-24-7687-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7687-2024","url":null,"abstract":"Abstract. This study investigated the potential effects of changes in inorganics on aerosol water uptake and, thus, on secondary organic aerosol (SOA) formation in wintertime haze based on the size-resolved measurements of non-refractory fine particulate matter (NR-PM2.5) in Xi'an, northwestern China. The composition of inorganic aerosol showed significant changes in winter 2018–2019 compared to winter 2013–2014, shifting from a sulfate-rich profile to a nitrate-rich profile. In particular, the fraction of sulfate and chloride decreased, but that of nitrate increased in the entire size range, while ammonium mainly increased at larger particle sizes. These changes thus resulted in a size-dependent evolution in water uptake. Increased water uptake was observed in most cases, mainly associated with enhanced contributions of both nitrate and ammonium, with the highest increase ratio reaching 5 %–35 % at larger particle sizes and higher relative humidity (RH>70 %). The non-negligible influence of chloride on aerosol water uptake was also emphasized. The random forest analysis coupled with a Shapley additive explanation algorithm (SHAP) further showed an enhanced relative importance of aerosol water in impacting SOA formation. Aerosol water exhibited a significant contribution to SOA formation during winter 2018–2019, particularly at larger particle sizes. The SHAP value of aerosol water increased alongside higher levels of aerosol water, indicating an enhanced contribution of aerosol water to SOA formation. This implies that the majority of enhanced aerosol water uptake at larger particle sizes and high RH might facilitate the efficient aqueous-phase SOA formation. This study highlights the key role of aerosol water as a medium to link inorganics and organics in their multiphase processes. As challenges to further improve China's air quality remain and because SOA plays an increasing role in haze pollution, these results provide insight into the size-resolved evolution characteristics and offer guidance for future controls.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"29 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553346","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":"Impact of wildfire smoke on Arctic cirrus formation, part 1: analysis of MOSAiC 2019–2020 observations","authors":"Albert Ansmann, Cristofer Jimenez, Johanna Roschke, Johannes Bühl, Kevin Ohneiser, Ronny Engelmann, Martin Radenz, Hannes Griesche, Julian Hofer, Dietrich Althausen, Daniel A. Knopf, Sandro Dahlke, Tom Gaudek, Patric Seifert, Ulla Wandinger","doi":"10.5194/egusphere-2024-2008","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2008","url":null,"abstract":"&lt;strong&gt;Abstract.&lt;/strong&gt; The number of wildfire smoke layers in the upper troposphere per fire season increased at mid and high northern latitudes during the last years. To consider smoke in weather and climate models appropriately, the influence of smoke on a variety of atmospheric processes needs to be explored in detail. In this study, we focus on the potential impact of wildfire smoke on cirrus formation. For the first time, state-of-the-art aerosol and cirrus observations with lidar and radar, presented in part 1 of a series of two articles, are closely linked to comprehensive modeling of gravity-wave-induced ice nucleation in cirrus evolution processes, presented in part 2. The complex study is based on aerosol and ice cloud observations in the central Arctic during the one-year MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition. For almost a year (from the summer of 2019 to the spring of 2020), aged Siberian wildfire smoke polluted the tropopause region over the central Arctic and many cirrus systems developed in the polluted upper troposphere. Goal of the data analysis (part 1) is to provide observational evidence for a dominating impact of aged wildfire smoke (organic aerosol particles) on cirrus formation in the central Arctic (over the MOSAiC research icebreaker Polarstern) during the winter half year of 2019–2020. Aim of the simulations in part 2 is to gain a deeper and more detailed insight into the potential smoke impact on ice nucleation as a function of observed aerosol and meteorological conditions (temperature, relative humidity) and by considering realistic gravity wave characteristics (updraft speed, wave amplitude). Vertical movements of air parcels are essential to initiate cloud formation. The measurements presented in part 1 were conducted during the winter half year (October to March), aboard the ice breaker Polarstern. The research vessel Polarstern drifted with the pack ice in the central Arctic mainly at latitudes &gt;85 °N during the winter half year. The cirrus statistics show typical properties of ice clouds of the synoptic cirrus category (top-down generation of cirrus structures). The ice clouds mostly started to evolve at heights close to the tropopause. Cirrus top temperatures accumulated between −60 and −75 °C. The cirrus optical thickness (COT at 532 nm) of the ice clouds covered a wide range of values from &lt; 0.03 (subvisible cirrus fraction, 25 % out of all cases) over 0.03–0.3 (visible thin cirrus, 40 %) to &gt; 0.3 (opaque cirrus fraction, 35 %). In about 30 % out of all high altitude lidar observations, cirrus signatures were detected, much more than expected (10 %). This fact may be taken as a first hint that wildfire smoke was significantly involved in Arctic cirrus formation. The smoke particle surface area concentration around the tropopause was of the order of 5–15 µm&lt;sup&gt;2&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt; and indicated considerably enhanced levels of aerosol pollutio","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"17 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553351","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":"Towards a sector-specific CO∕CO2 emission ratio: satellite-based observations of CO release from steel production in Germany","authors":"Oliver Schneising, Michael Buchwitz, Maximilian Reuter, Michael Weimer, Heinrich Bovensmann, John P. Burrows, Hartmut Bösch","doi":"10.5194/acp-24-7609-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7609-2024","url":null,"abstract":"Abstract. Global crude steel production is expected to continue to increase in the coming decades to meet the demands of the growing world population. Currently, the dominant steelmaking technology worldwide is the conventional highly CO2-intensive blast furnace–basic oxygen furnace production route (also known as the Linz–Donawitz process), which uses iron ore as raw material and coke as a reducing agent. As a result, large quantities of special gases that are rich in carbon monoxide (CO) are by-products of the various stages of the steelmaking process. Given the challenges associated with satellite-based estimates of carbon dioxide (CO2) emissions at the scale of emitting installations due to significant background levels, co-emitted CO may serve as a valuable indicator of the carbon footprint of steel plants. We show that regional CO release from steel production sites can be monitored from space using 5 years of measurements (2018–2022) from the TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinel-5 Precursor satellite, benefiting from its relatively high spatial resolution and daily global coverage. We analyse all German steel plants with blast furnaces and basic oxygen furnaces and obtain associated CO emissions in the range of 50–400 kt yr−1 per site. A comparison with the respective CO2 emissions on the level of emitting installations available from emissions trading data of the European Union Emissions Trading System yields a linear relationship with a sector-specific CO/CO2 emission ratio for the analysed steelworks of 3.24 % [2.73–3.89; 1σ], suggesting the feasibility of using CO as a proxy for CO2 emissions from comparable steel production sites. An evaluation at other steel production sites indicates that the derived CO/CO2 emission ratio is also representative of other highly optimised state-of-the-art Linz–Donawitz steelworks outside Germany and that the emission ratio is potentially valuable for estimating sector-specific CO2 emissions from remotely sensed CO emissions, provided that the underlying CO emission estimate is not affected by other sources.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"31 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553347","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":"Airborne observations of upper troposphere and lower stratosphere composition change in active convection producing above-anvil cirrus plumes","authors":"Andrea E. Gordon, Cameron R. Homeyer, Jessica B. Smith, Rei Ueyama, Jonathan M. Dean-Day, Elliot L. Atlas, Kate Smith, Jasna V. Pittman, David S. Sayres, David M. Wilmouth, Apoorva Pandey, Jason M. St. Clair, Thomas F. Hanisco, Jennifer Hare, Reem A. Hannun, Steven Wofsy, Bruce C. Daube, Stephen Donnelly","doi":"10.5194/acp-24-7591-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7591-2024","url":null,"abstract":"Abstract. Tropopause-overshooting convection in the midlatitudes provides a rapid transport pathway for air from the lower troposphere to reach the upper troposphere and lower stratosphere (UTLS) and can result in the formation of above-anvil cirrus plumes (AACPs) that significantly hydrate the stratosphere. Such UTLS composition changes alter the radiation budget and impact climate. Novel in situ observations from the NASA Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field campaign are used in this study to examine UTLS impacts from AACP-generating overshooting convection. Namely, a research flight on 31 May 2022 sampled active convection over the state of Oklahoma for more than 3 h with the NASA ER-2 high-altitude research aircraft. An AACP was bisected during this flight, providing the first such extensive in situ sampling of this phenomenon. The convective observations reveal pronounced changes in air mass composition and stratospheric hydration up to altitudes of 2.3 km above the tropopause and concentrations more than double background levels. Unique dynamic and trace gas signatures were found within the AACP, including enhanced vertical mixing near the AACP edge and a positive correlation between water vapor and ozone. Moreover, the water vapor enhancement within the AACP was found to be limited to the saturation mixing ratio of the low temperature overshoot and AACP air. Comparison with all remaining DCOTSS flights demonstrates that the 31 May 2022 flight had some of the largest tropospheric tracer and water vapor perturbations in the stratosphere and within the AACP.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"32 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141546209","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":"Measurement report: TURBAN observation campaign combining street-level low-cost air quality sensors and meteorological profile measurements in Prague","authors":"Petra Bauerová, Josef Keder, Adriana Šindelářová, Ondřej Vlček, William Patiño, Jaroslav Resler, Pavel Krč, Jan Geletič, Hynek Řezníček, Martin Bureš, Kryštof Eben, Michal Belda, Jelena Radović, Vladimír Fuka, Radek Jareš, Igor Ezau","doi":"10.5194/egusphere-2024-1222","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1222","url":null,"abstract":"<strong>Abstract.</strong> Within the TURBAN project, a \"Legerova campaign\" focusing on air quality and meteorology in the traffic-loaded part of the Prague city (Czech Republic) was carried out from 30 May 2022 to 28 March 2023. The network comprised of 20 combined low-cost sensor (LCS) stations for NO₂, O₃, PM₁₀ and PM_2.5concentrations, along with a mobile meteorological mast, a single-channel microwave radiometer and Doppler LIDAR for measurement of vertical temperature and wind profiles. Significant individual deviations of LCSs were detected during the 165 day initial field test of all units at the urban background Prague 4-Libuš reference station (coefficient of variation 17–28 %). Implementing the Multivariate Adaptive Regression Splines method for correction reduced the LCS inter-individual variability and improved correlation with reference monitors in all pollutants (R² 0.88–0.97). The LCSs' data drifts and ageing were checked by the double mass curve method for the entire measurement period. During the Legerova campaign, the highest NO₂ concentrations were in traffic-loaded street canyons with continuous building blocks and several traffic lights. Aerosol pollution showed very little variation between the monitored streets. The highest PM₁₀ and PM_2.5 concentrations were recorded during temperature inversions and an episode involving pollution transported from a large forest fire in northern Czech Republic in July 2022. This report provides valuable data to support the validation of various predictive models dealing with complex urban environment, such as microscale LES model PALM tested in the TURBAN project.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"67 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141546212","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":"Technical note: Retrieval of the supercooled liquid fraction in mixed-phase clouds from Himawari-8 observations","authors":"Ziming Wang, Husi Letu, Huazhe Shang, Luca Bugliaro","doi":"10.5194/acp-24-7559-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7559-2024","url":null,"abstract":"Abstract. The supercooled liquid fraction (SLF) in mixed-phase clouds (MPCs) is an essential variable of cloud microphysical processes and climate sensitivity. However, the SLF is currently calculated in spaceborne remote sensing only as the cloud phase–frequency ratio of adjacent pixels, which results in a loss of the original resolution in observations of cloud liquid or ice content within MPCs. Here, we present a novel method for retrieving the SLF in MPCs based on the differences in radiative properties of supercooled liquid droplets and ice particles at visible (VIS) and shortwave infrared (SWI) channels of the geostationary Himawari-8. Liquid and ice water paths are inferred by assuming that clouds are composed of only liquid or ice, with the real cloud water path (CWP) expressed as a combination of these two water paths (SLF and 1-SLF as coefficients), and the SLF is determined by referring to the CWP from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). The statistically relatively small cloud phase spatial inhomogeneity at a Himawari-8 pixel level indicates an optimal scene for cloud retrieval. The SLF results are comparable to global SLF distributions observed by active instruments, particularly for single-layered cloud systems. While accessing the method's feasibility, SLF averages are estimated between 74 % and 78 % in Southern Ocean (SO) stratocumulus across seasons, contrasting with a range of 29 % to 32 % in northeastern Asia. The former exhibits a minimum SLF around midday in summer and a maximum in winter, while the latter trend differs. This novel algorithm will be valuable for research to track the evolution of MPCs and constrain the related climate impact.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"16 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141546211","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}