Atmospheric Chemistry and Physics最新文献

{"title":"The Impact of Aerosol on Cloud Water: A Heuristic Perspective","authors":"Fabian Hoffmann, Franziska Glassmeier, Graham Feingold","doi":"10.5194/egusphere-2024-1725","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1725","url":null,"abstract":"<strong>Abstract.</strong> Aerosol-cloud interactions modulate the role of clouds in Earth's climate. We derive, evaluate, and apply a simple model to understand aerosol-mediated cloud water adjustments in stratocumulus based on only two prognostic equations for the integrated cloud water <em>L</em> and droplet number concentration <em>N</em>. The model is solved numerically and analytically, and agrees well with documented large-eddy simulation data and satellite retrievals. A tight relationship between adjustments at low and high <em>N</em> is found, revealing the influence of non-precipitation processes (primarily entrainment) on adjustments in precipitating clouds. Furthermore, it is shown that adjustments in non-precipitating clouds tend to be positively biased by external <em>L</em> or <em>N</em> perturbations, while adjustments in precipitating clouds are barely susceptible. By deliberately reducing the complexity of the underlying system, this study constitutes a way forward to facilitate process-level understanding of cloud water adjustments.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"43 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435794","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":"AERO-MAP: A data compilation and modelling approach to understand spatial variability in fine and coarse mode aerosol composition","authors":"Natalie M. Mahowald, Longlei Li, Julius Vira, Marje Prank, Douglas S. Hamilton, Hitoshi Matsui, Ron L. Miller, Louis Lu, Ezgi Akyuz, Daphne Meidan, Peter G. Hess, Heikki Lihavainen, Christine Wiedinmyer, Jenny Hand, Maria Grazia Alaimo, Célia Alves, Andres Alastuey, Paulo Artaxo, Africa Barreto, Francisco Barraza, Silvia Becagli, Giulia Calzolai, Shankararaman Chellam, Ying Chen, Patrick Chuang, David D. Cohen, Cristina Colombi, Evangelia Diapouli, Gaetano Dongarra, Konstantinos Eleftheriadis, Johann Engelbrecht, Corinne Galy-Lacaux, Cassandra Gaston, Dario Gomez, Yenny González Ramos, Roy M. Harrison, Chris Heyes, Barak Herut, Philip Hopke, Christoph Hüglin, Maria Kanakidou, Zsofia Kertesz, Zbigniew Klimont, Katriina Kyllönen, Fabrice Lambert, Xiaohong Liu, Remi Losno, Franco Lucarelli, Willy Maenhaut, Beatrice Marticorena, Randall V. Martin, Nikolaos Mihalopoulos, Yasser Morera-Gomez, Adina Paytan, Joseph Prospero, Sergio Rodríguez, Patricia Smichowski, Daniela Varrica, Brenna Walsh, Crystal Weagle, Xi Zhao","doi":"10.5194/egusphere-2024-1617","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1617","url":null,"abstract":"<strong>Abstract.</strong> Aerosol particles are an important part of the Earth system, but their concentrations are spatially and temporally heterogeneous, as well as variable in size and composition. Particles can interact with incoming solar radiation and outgoing long wave radiation, change cloud properties, affect photochemistry, impact surface air quality, change the surface albedo of snow and ice, and modulate carbon dioxide uptake by the land and ocean. High particulate matter concentrations at the surface represent an important public health hazard. There are substantial datasets describing aerosol particles in the literature or in public health databases, but they have not been compiled for easy use by the climate and air quality modelling community. Here we present a new compilation of PM_2.5and PM₁₀ aerosol observations, focusing on the spatial variability across different observational stations, including composition, and demonstrate a method for comparing the datasets to model output. Overall, most of the planet or even the land fraction does not have sufficient observations of surface concentrations, and especially particle composition to understand the current distribution of particles. Most climate models exclude 10–30 % of the aerosol particles in both PM_2.5and PM₁₀ size fractions across large swaths of the globe in their current configurations, with ammonium nitrate and agricultural dust aerosol being the most important omitted aerosol types.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"18 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435842","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":"Microphysical characteristics of precipitation within convective overshooting over East China observed by GPM DPR and ERA5","authors":"Nan Sun, Gaopeng Lu, Yunfei Fu","doi":"10.5194/acp-24-7123-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7123-2024","url":null,"abstract":"Abstract. We examine the geographical distribution and microphysical three-dimensional structure of convective overshooting over East China by matching the Global Precipitation Measurement Dual-frequency Precipitation Radar (GPM DPR) instrument with the European Centre for Medium-Range Weather Forecasts Fifth-Generation Reanalysis (ERA5). Convective overshooting mainly occurs over Northeast China (NC) and northern Middle and East China (MEC), and its frequency varies from 4×10-4 to 5.4×10-3. Radar reflectivity of convective overshooting over NC accounts for a higher proportion below the freezing level, while MEC and South China (SC) account for a higher proportion above the freezing level, indicating stronger upward motion and more ice crystal particles. The microphysical processes within convective overshooting are unique, leading to various properties of the droplets in precipitation. Droplets of convective overshooting are large but sparse, with an effective droplet radius of nearly 2.5 mm below 10 km, which is about twice that of non-overshooting precipitation. The findings of this study may have important implications for the microphysical evolution associated with convective overshooting and provide more accurate precipitation microphysical parameters as input for model simulations.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"75 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435834","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":"On the dynamics of ozone depletion events at Villum Research Station in the High Arctic","authors":"Jakob Boyd Pernov, Jens Liengaard Hjorth, Lise Lotte Sørensen, Henrik Skov","doi":"10.5194/egusphere-2024-1676","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1676","url":null,"abstract":"<strong>Abstract.</strong> Ozone depletion events (ODEs) occur every spring in the Arctic and have implications for the atmospheric oxidizing capacity, radiative balance, and mercury oxidation. Here we comprehensively analyze ozone, ODEs, and their connection to meteorological and air mass history variables through statistical analyses, back-trajectories, and machine learning (ML) from observations at Villum Research Station, Station Nord, Greenland. We show that the ODE frequency and duration peak in May followed by April and March, which is likely related to air masses spending more time over sea ice and increases in radiation from March to May. Back-trajectories indicate that, as spring progresses, ODE air masses spend more time within the mixed layer and the geographic origins move closer to Villum. ODE frequency and duration are increasing during May (low confidence) and April (high confidence), respectively. Our analysis revealed that ODEs are favorable under sunny, calm conditions with air masses arriving from northerly wind directions with sea ice contact. The ML model was able to reproduce the ODE occurrence and illuminated that radiation, time over sea ice, and temperature were the most important variables for modeling ODEs during March, April, and May, respectively. Several variables displayed threshold ranges for contributing to the positive prediction of ODEs vs Non-ODEs, notably temperature, radiation, wind direction, time spent over sea ice, and snow. Our ML methodology provides a framework for investigating and comparing the environmental drivers of ODEs between different Arctic sites and can be applied to other atmospheric phenomena (e.g., atmospheric mercury depletion events).","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"74 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141435728","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":"Emission characteristics of reactive organic gases (ROGs) from industrial volatile chemical products (VCPs) in the Pearl River Delta (PRD), China","authors":"Sihang Wang, Bin Yuan, Xianjun He, Ru Cui, Xin Song, Yubin Chen, Caihong Wu, Chaomin Wang, Yibo Huangfu, Xiao-Bing Li, Boguang Wang, Min Shao","doi":"10.5194/acp-24-7101-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7101-2024","url":null,"abstract":"Abstract. Volatile chemical products (VCPs) have become an important source of reactive organic gases (ROGs) in urban areas worldwide. Industrial activities can also utilize a large number of VCPs and emit many organic gases into the atmosphere. Due to multiple sampling and measurement challenges, only a subset of ROG species is usually measured for many industrial VCP sources. This study aims to investigate the emissions of ROGs from five industrial VCP sources in the Pearl River Delta (PRD) region of China, including the shoemaking, plastic surface coating, furniture coating, printing, and ship coating industries. A more comprehensive speciation of ROG emissions from these industrial VCP sources was developed by the combination of proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) and the gas chromatography–mass spectrometer/flame ionization detector (GC–MS/FID). Our study identified oxygenated ROG species (OVOCs) as representative ROGs emitted from these sources, which are highly related to specific chemicals used during industrial activities. Moreover, mass spectra similarity analysis revealed significant dissimilarities among the ROG emissions from industrial activities, indicating substantial variations between different industrial VCP sources. Except for the ship coating industry utilizing solvent-borne coatings, the proportions of OVOCs range from 67 % to 96 % in total ROG emissions and 72 % to 97 % in total OH reactivity (OHR) for different industrial sources, while the corresponding contributions of OVOCs in the ship coating industry are only 16 ± 3.5 % and 15 ± 3.6 %. The industrial VCP sources associated with solvent-borne coatings exhibited a higher ozone formation potential (OFP), reaching as high as 5.5 and 2.7 g O3 g−1 ROGs for the ship coating and furniture coating industries, primarily due to contributions from aromatics. We find that a few species can contribute the majority of the ROG emissions and also their OHR and OFP from various industrial VCP sources. Our results suggest that ROG treatment devices may have limited effectiveness for all ROGs, with treatment efficiencies ranging from −12 % to 68 %. Furthermore, we found that ambient measurements in industrial areas have been significantly impacted by industrial VCP sources, and ROG pairs (e.g., methyl ethyl ketone (MEK) / C8 aromatics ratio) can be utilized as reliable evidence by using high-time-resolution ROG measurements from PTR-ToF-MS. Our study demonstrated the importance of measuring a large number of ROGs using PTR-ToF-MS for characterizing ROG emissions from industrial VCP sources.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"35 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141430348","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":"Deciphering anthropogenic and biogenic contributions to selected non-methane volatile organic compound emissions in an urban area","authors":"Arianna Peron, Martin Graus, Marcus Striednig, Christian Lamprecht, Georg Wohlfahrt, Thomas Karl","doi":"10.5194/acp-24-7063-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7063-2024","url":null,"abstract":"Abstract. The anthropogenic and biogenic contributions of isoprene, monoterpenes, sesquiterpenes and methanol in an urban area were estimated based on direct eddy covariance flux observations during four campaigns between 2018 and 2021. While these compounds are typically thought to be dominated by biogenic sources on regional and global scales, the role of potentially significant anthropogenic emissions in urban areas has been recently debated. Typical fluxes of isoprene, monoterpenes and sesquiterpenes were on the order of 0.07 ± 0.02, 0.09 and 0.003 nmol m−2 s−1 during spring. During summer, emission fluxes of isoprene, monoterpenes and sesquiterpenes were higher on the order of 0.85 ± 0.09, 0.11 and 0.004 nmol m−2 s−1. It was found that the contribution of the anthropogenic part is strongly seasonally dependent. For isoprene, the anthropogenic fraction can be as high as 64 % in spring but is typically very low < 18 % during the summer season. For monoterpenes, the anthropogenic fraction was estimated to be between 43 % in spring and less than 20 % in summer. With values of 2.8 nmol m−2 s−1 in spring and 3.2 nmol m−2 s−1 in summer, methanol did not exhibit a significant seasonal variation of observed surface fluxes. However, there was a difference in emissions between weekdays and weekends (about 2.3 times higher on weekdays in spring). This suggests that methanol emissions are likely influenced by anthropogenic activities during all seasons.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"48 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141430347","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":"In situ measurement of organic aerosol molecular markers in urban Hong Kong during a summer period: temporal variations and source apportionment","authors":"Hongyong Li, Xiaopu Lyu, Likun Xue, Yunxi Huo, Dawen Yao, Haoxian Lu, Hai Guo","doi":"10.5194/acp-24-7085-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7085-2024","url":null,"abstract":"Abstract. Organic aerosol (OA) is a significant constituent of urban particulate matter (PM), and molecular markers therein provide information on the sources and formation mechanisms. With the in situ measurement of over 70 OA molecular markers in a summer month at a bihourly resolution, this study focused on the temporal variations in representative markers and dynamic source contributions to OA at an urban site in Hong Kong SAR (HK). The levels of secondary OA (SOA) markers were markedly elevated (p < 0.05) in the short-duration cases with continental and coastal air relative to those in the most common marine air, and the primary markers primarily contained local characteristics. The troughs showed the enhancements of many SOA markers (p < 0.05), which appeared to be related to the high relative humidity. The diurnal patterns of 2-methyltetrols varied in differed cases, and their aqueous formation at night seemed plausible, particularly in the presence of troughs. Eight sources were identified for the organic matter in submicron PM (PM1-OM). Despite being an urban site, the mean SOA contribution (66.1 ± 10.5 %), primarily anthropogenic, was significant. Anthropogenic SOA dominated in the cases with continental and coastal air and in the early afternoon. Local cooking and vehicle emissions became predominant in the case of marine air without troughs. Even averaged over the study period in this summer month with the prevalence of marine air, primary cooking emissions contributed up to 44.2 % to PM1-OM in the early evening. The study highlighted the need to control regional anthropogenic SOA and local cooking emissions to mitigate PM pollution in HK.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"25 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141430367","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":"Upper tropospheric pollutants observed by MIPAS: geographic and seasonal variations","authors":"Norbert Glatthor, Gabriele P. Stiller, Thomas von Clarmann, Bernd Funke, Sylvia Kellmann, Andrea Linden","doi":"10.5194/egusphere-2024-1793","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1793","url":null,"abstract":"<strong>Abstract.</strong> We present a global climatology of upper tropospheric hydrogen cyanide (HCN), carbon monoxide (CO), acetylene (C₂H₂), ethane (C₂H₆), peroxyacetyl nitrate (PAN) and formic acid (HCOOH), obtained from MIPAS/Envisat observations between 2002 and 2012. At northern mid- and high latitudes the biomass burning tracer HCN as well as CO, PAN and HCOOH exhibit maxima during spring and/or summer and minima during winter. On the contrary, maximum northern extra-tropical C₂H₂ and C₂H₆ amounts were measured during winter and spring and minimum values during summer and fall. In the tropics and subtropics, enhanced amounts of all pollutants were observed during all seasons, especially widespread and up to southern mid-latitudes during austral spring. Other characteristic features are eastward transport of anthropogenic C₂H₆ and of biogenic HCOOH from Central and North America in boreal summer, accumulation of pollutants in the Asian Monsoon Anticyclone and enhanced C₂H₂ over South-East Asia in boreal winter. Clear indication of biogenic release of HCOOH was also found above tropical South America and Africa. A global correlation analysis of the other pollutants with HCN corroborates common release by biomass burning as source of the widespread southern hemispheric pollution during austral spring. Further, high correlation with HCN points to biomass burning as major source of tropical and subtropical C₂H₂ and PAN during most of the year. In the northern extra-tropics there are generally low correlations with HCN during spring and early summer, indicating the influence of anthropogenic and biogenic sources. However, in August there are stronger correlations above Siberia and boreal North America, which points to common release by boreal fires. This is confirmed by the respective enhancement ratios (ERs). The ERs measured above North-East Africa fit well to the emission ratios of the dominant local fire type (savanna burning) for C₂H₂, while those for CO, C₂H₆ and HCOOH rather indicate tropical forest fires or additional anthropogenic or biogenic sources. The southern hemispheric ΔC₂H₆/ΔHCN ERs obtained during August to October are in good agreement with the emission ratio for savanna fires. The same applies for ΔC₂H₂/ΔHCN in August and for ΔHCN/ΔCO as well as for ΔHCOOH/ΔHCN in October.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"12 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141430556","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":"Role of chemical production and depositional losses on formaldehyde in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM)","authors":"T. Nash Skipper, Emma L. D'Ambro, Forwood C. Wiser, V. Faye McNeill, Rebecca H. Schwantes, Barron H. Henderson, Ivan R. Piletic, Colleen B. Baublitz, Jesse O. Bash, Andrew R. Whitehill, Lukas C. Valin, Asher P. Mouat, Jennifer Kaiser, Glenn M. Wolfe, Jason M. St. Clair, Thomas F. Hanisco, Alan Fried, Bryan K. Place, Havala O. T. Pye","doi":"10.5194/egusphere-2024-1680","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1680","url":null,"abstract":"<strong>Abstract.</strong> Formaldehyde (HCHO) is an important air pollutant due to its direct health effects as an air toxic that contributes to elevated cancer risk, its role in ozone formation, and its role as a product from oxidation of most gas phase reactive organic carbon. We make several updates affecting secondary production of HCHO in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) in the Community Multiscale Air Quality (CMAQ) model. Secondary HCHO from isoprene and monoterpenes is increased, correcting an underestimate in the current version. Simulated 2019 June–August surface HCHO during peak photochemical production (11 am–3 pm) increased by 0.6 ppb (32 %) over the southeastern US and by 0.2 ppb (13 %) over the entire contiguous US. The increased HCHO compares more favorably with satellite-based observations from TROPOMI and observations from an aircraft campaign. Evaluation against hourly surface observations indicates a missing nighttime sink for HCHO which can be ameliorated by adding bidirectional exchange of HCHO and a leaf wetness dependent deposition process which increases nighttime deposition, decreasing 2019 June–August nocturnal (8 pm–4 am) surface HCHO by 1.1 ppb (36 %) over the southeastern US and 0.5 ppb (29 %) over the entire contiguous US. The ability of CRACMM to capture peak levels of HCHO at midday is improved, particularly at sites in the northeastern US, while peak levels at southeastern US sites are improved though still lower than observed. Using established risk assessment methods, lifetime exposure of the contiguous U.S. population (~320 million) to ambient HCHO levels predicted here may result in 6200 lifetime cancer cases, 40 % of which are from controllable anthropogenic emissions of nitrogen oxides and reactive organic compounds. Chemistry updates will be available in CRACMM version 2 (CRACMM2) in CMAQv5.5.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"11 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425475","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":"Signs of climate variability in double tropopause global distribution from radio occultation data","authors":"Alejandro de la Torre, Peter Alexander, Torsten Schmidt, Andrea K. Steiner, Florian Ladstädter, Rodrigo Hierro, Pablo Llamedo","doi":"10.5194/egusphere-2024-1654","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1654","url":null,"abstract":"<strong>Abstract.</strong> In a standard atmosphere, there is a single lapse rate tropopause (in what follows, tropopause) that separates the troposphere below from the stratosphere above. However, in certain situations, such as in regions of strong vertical wind shear or associated with certain weather phenomena, a second tropopause layer may form above the standard tropopause. The presence of a double tropopause (DT) can have implications for atmospheric and climate studies, as it may be associated with dynamic and complex weather patterns. Based on 14 years of temperature profiles retrieved by GNSS radio occultation and the resulting DT, a possible relationship between the spatio-temporal distribution of the relative number of DT to simple tropopauses (NDT) (<em>or dependent variable</em>) and a set of monthly climate indices (<em>or features</em>) is explored with a focus on the methodological approach. A cluster analysis is applied to geographically associate the DT occurrences with the climate indices. Then a multivariate linear regression is constructed using a progression of different models to identify the relevant features for the occurrence of DTs. On a global scale, from a hierarchical cluster analysis six sub-regions with different location and spread characteristics are identified. In addition to the condition of linearity in the residuals, the performance of each model in the train and test populations is evaluated to discard possible overfitting. The required conditions of non-collinearity, stationarity and cross-correlation between the features and the relative number of NDT after the removal of the climatological mean for each month (NDT’) are checked. Mean squared errors, adjusted coefficient of determination (adjusted R²) and number of degrees of freedom (F-statistic) parameters are evaluated for each model obtained. Taking into account the constraints of the present analysis, the most relevant climatic indices for the distribution of NDT' are identified.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":"65 1","pages":""},"PeriodicalIF":6.3,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425534","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}