Journal of Geophysical Research: Atmospheres最新文献

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Local and Remote Effects of the Sub-Grid Turbulent Orographic Form Drag on the Summer Monsoon Precipitation Over Eastern China 华东地区夏季季风降水受亚栅格湍流貌阻力的局地和远程影响
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-18 DOI: 10.1029/2024JD041173
Yuchen Zhou, Anning Huang, Xin Li, Chunlei Gu, Yang Wu
{"title":"Local and Remote Effects of the Sub-Grid Turbulent Orographic Form Drag on the Summer Monsoon Precipitation Over Eastern China","authors":"Yuchen Zhou,&nbsp;Anning Huang,&nbsp;Xin Li,&nbsp;Chunlei Gu,&nbsp;Yang Wu","doi":"10.1029/2024JD041173","DOIUrl":"https://doi.org/10.1029/2024JD041173","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>The sub-grid turbulent orographic form drag (STOFD) significantly affects the regional circulation and precipitation. This study explores the local and remote effects of the STOFD on the summer monsoon precipitation across Eastern China using the Regional Climate Model Version 4 adopting a STOFD scheme. Results indicate that the local and remote effects of the STOFD primarily influence the improvement of summer precipitation simulation in the Southeastern and Northern China, respectively. The local effects of the STOFD can lead to 37.1% and 10.7% reduction of the absolute error and the root mean square error (RMSE) of simulated summer precipitation in the Southeastern China with complex sub-grid terrains. The remote effects of the STOFD within the Indochina Peninsula and Yunnan-Guizhou Plateau result in the absolute error and RMSE of simulated summer precipitation in the Northern China with mild sub-grid terrain decreased by 90.1% and 32.9%, respectively. Moreover, the remote effects of the STOFD within the Tianshan Mountains and Tibetan Plateau can clearly improve the simulated precipitation in both the Southeastern and Northern China. The disturbances generated by the local effects of the STOFD are more locally concentrated than those produced by the STOFD remote effects, leading to a more significant improvement of precipitation simulation in the Southeastern China. While the disturbances resulted from the remote effects of the STOFD affect the summer precipitation in both the Southeastern and Northern China obviously. This study highlights the significance of the remote effects of the STOFD in improving the summer precipitation simulation in Eastern China.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142449060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Atmospheric Microplastics Emission Source Potentials and Deposition Patterns in Semi-Arid Croplands of Northern China 中国北方半干旱农田的大气微塑料排放源潜力和沉积模式
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-18 DOI: 10.1029/2024JD041546
Xin Long, Shuang Zhang, Dasheng Huang, Chunping Chang, Chao Peng, Kai Liu, Kai Wang, Xuejun Liu, Tzung-May Fu, Yan Han, Pengcheng Li, Yongming Han, Junji Cao, Xueke Li, Zhongling Guo, Yang Chen
{"title":"Atmospheric Microplastics Emission Source Potentials and Deposition Patterns in Semi-Arid Croplands of Northern China","authors":"Xin Long,&nbsp;Shuang Zhang,&nbsp;Dasheng Huang,&nbsp;Chunping Chang,&nbsp;Chao Peng,&nbsp;Kai Liu,&nbsp;Kai Wang,&nbsp;Xuejun Liu,&nbsp;Tzung-May Fu,&nbsp;Yan Han,&nbsp;Pengcheng Li,&nbsp;Yongming Han,&nbsp;Junji Cao,&nbsp;Xueke Li,&nbsp;Zhongling Guo,&nbsp;Yang Chen","doi":"10.1029/2024JD041546","DOIUrl":"https://doi.org/10.1029/2024JD041546","url":null,"abstract":"<p>Frequent wind erosion events in semi-arid regions can lead to significant atmospheric microplastic (MP) emissions from croplands. We examine observed and predicted characteristics of atmospheric MPs over cropland in Northern China. Measurements showed that fibers were the predominant morphology, accounting for 69% of the 198 observed MPs. The observed atmospheric MP abundance varied widely, averaging 0.088 # m<sup>−3</sup> in the absence of air masses passing through near-surface croplands and increasing significantly to 0.26 # m<sup>−3</sup> when such air masses were present. The predictions of deposition flux for atmospheric MPs over croplands indicated a spatial variation ranging from less than 0.5 g km<sup>−2</sup> day<sup>−1</sup> in the north to over 15 g km<sup>−2</sup> day<sup>−1</sup> in the south, corresponding to an average of approximately 13.3 g km<sup>−2</sup> day<sup>−1</sup>. Our findings highlight the dual role of surface soil as both a potential source and sink of atmospheric MPs, underscoring the need for further research on the regional dynamics of wind-driven MP emissions and their associated ecosystem health risks in semi-arid croplands.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142449219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Evaluation of the Representation of Raindrop Self-Collection and Breakup in Two-Moment Bulk Models Using a Multifrequency Radar Retrieval 利用多频雷达检索评估两时刻体积模型中雨滴自聚和破裂的表现形式
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-17 DOI: 10.1029/2024JD041269
L. Niquet, F. Tridon, P. Grzegorczyk, A. Causse, B. Bordet, W. Wobrock, C. Planche
{"title":"Evaluation of the Representation of Raindrop Self-Collection and Breakup in Two-Moment Bulk Models Using a Multifrequency Radar Retrieval","authors":"L. Niquet,&nbsp;F. Tridon,&nbsp;P. Grzegorczyk,&nbsp;A. Causse,&nbsp;B. Bordet,&nbsp;W. Wobrock,&nbsp;C. Planche","doi":"10.1029/2024JD041269","DOIUrl":"https://doi.org/10.1029/2024JD041269","url":null,"abstract":"<p>Using multifrequency radar observations providing raindrop size distribution evolution with high spatial and temporal resolution, this study aims to assess the ability of different parameterizations of raindrop self-collection and breakup processes applied in mesoscale models, to reproduce the statistics derived from observations. The stratiform zones of two types of precipitating systems are studied, a frontal situation that occurred over Finland in June 2014 and a squall line system observed over Oklahoma in June 2011. An analysis method for determining raindrop trajectories was used to obtain the temporal variation of the total raindrop concentration from the observations. The resulting raindrop concentration rate as a function of the mean volume diameter reveals significant differences with the parameterizations currently used in two-moment bulk microphysics schemes. These results show that even if they produce variations in raindrop concentration of the same order of magnitude as the observations, the current parameterizations diverge from the median of the observations, resulting in an overestimation of either the self-collection or the breakup process. From the median of radar observations, new parameterizations of the self-collection and breakup processes and of rain self-collection efficiency are developed and can be implemented in two-moment bulk microphysics schemes.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Distinct Radiative and Chemical Impacts Between the Equatorial and Northern Extratropical Volcanic Injections 赤道和北热带外火山喷入物之间不同的辐射和化学影响
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-16 DOI: 10.1029/2024JD041690
Yifeng Peng, Wenshou Tian, Chenwei Li, Haiyang Xue, Pengfei Yu
{"title":"Distinct Radiative and Chemical Impacts Between the Equatorial and Northern Extratropical Volcanic Injections","authors":"Yifeng Peng,&nbsp;Wenshou Tian,&nbsp;Chenwei Li,&nbsp;Haiyang Xue,&nbsp;Pengfei Yu","doi":"10.1029/2024JD041690","DOIUrl":"https://doi.org/10.1029/2024JD041690","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Stratospheric volcanic aerosols can affect the global radiative balance and stratospheric composition. In this study, we analyze ensemble experiments with an interactive stratospheric aerosol microphysical general circulation model, designed to assess the climate forcing from large-magnitude explosive eruptions in the tropics and northern extratropics. Previous studies have generally identified a lower radiative forcing from extratropical eruptions from the shorter stratospheric lifetime of volcanic sulfate aerosols. However, our study finds that both the shorter lifetime and lower effective radiative forcing (ERF) efficacy contribute to the lower ERF in the northern extratropical eruptions. The simulated 2-year averaged ERF efficacy in northern extratropical eruptions is 22% lower than that in the equatorial eruptions due to the seasonal mismatch of peak stratospheric aerosol optical depth and solar radiation in the first year after a northern extratropical volcanic eruption. Additionally, equatorial eruptions accelerate the Brewer-Dobson circulation (BDC), while northern hemispheric (NH) extratropical eruptions decelerate the BDC branch in NH and accelerate the BDC branch in southern hemisphere (SH), leading to different spatio-temporal pattern of ozone anomalies. Consequently, dominated by the dynamical processes, equatorial eruption leads to ozone loss in tropics and increase in midlatitudes, while both northern extratropical summer and winter eruptions trigger ozone decrease in NH and increase in SH.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Vertical Profile Analysis of Cloud Feedbacks 云反馈的垂直概况分析
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-16 DOI: 10.1029/2023JD040530
Hideaki Kawai, Tsuyoshi Koshiro, Seiji Yukimoto
{"title":"Vertical Profile Analysis of Cloud Feedbacks","authors":"Hideaki Kawai,&nbsp;Tsuyoshi Koshiro,&nbsp;Seiji Yukimoto","doi":"10.1029/2023JD040530","DOIUrl":"https://doi.org/10.1029/2023JD040530","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Cloud feedback is the largest source of uncertainty in climate sensitivity. This feedback is generally discussed in terms of radiative flux at the top of the atmosphere, but the vertical distribution of the contribution of cloud changes to the top-of-atmosphere cloud feedback should be discussed to understand the feedback in greater detail. We have developed a simple analysis method called “vertical profile analysis of cloud feedback,” which simply uses radiative flux data from each level of the model. The analysis is applied for typical cloud regimes and the results are discussed together with cloud fraction change profiles. The advantages and disadvantages of the vertical profile analysis, compared with the commonly used International Satellite Cloud Climatology Project (ISCCP) histogram kernel method, are discussed. Our analysis has the advantage of resolving the detailed vertical profiles of the contribution to the top-of-atmosphere cloud feedback from the changes in cloud regimes associated with warming, such as reduced cloud cover and upward shifts of the cloud layer in subtropical low-cloud regions as well as the increased height of the melting layer in tropical deep convection. The main disadvantage is that the vertical profile analysis cannot represent the feedback components sorted by cloud optical thickness as in the ISCCP histogram kernel method.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Calculating Radio Emissions of Positive Streamer Phenomena Using 3D Simulations 利用三维模拟计算正流线现象的无线电发射
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-16 DOI: 10.1029/2024JD041385
Hemaditya Malla, Yihao Guo, Brian M. Hare, Steven Cummer, Alejandro Malagón-Romero, Ute Ebert, Sander Nijdam, Jannis Teunissen
{"title":"Calculating Radio Emissions of Positive Streamer Phenomena Using 3D Simulations","authors":"Hemaditya Malla,&nbsp;Yihao Guo,&nbsp;Brian M. Hare,&nbsp;Steven Cummer,&nbsp;Alejandro Malagón-Romero,&nbsp;Ute Ebert,&nbsp;Sander Nijdam,&nbsp;Jannis Teunissen","doi":"10.1029/2024JD041385","DOIUrl":"https://doi.org/10.1029/2024JD041385","url":null,"abstract":"<p>We study radio emissions from positive streamers in air using 3D simulations, from which the radiated electric field is computed by solving Jefimenko’s equations. The simulations are performed at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>0.5</mn>\u0000 <mspace></mspace>\u0000 <mi>b</mi>\u0000 <mi>a</mi>\u0000 <mi>r</mi>\u0000 </mrow>\u0000 <annotation> $0.5,mathrm{b}mathrm{a}mathrm{r}$</annotation>\u0000 </semantics></math> using two photoionization methods: the Helmholtz approximation for a photon density and a Monte Carlo method using discrete photons, with the latter being the most realistic. We consider cases with single streamers, streamer branching, streamers interacting with preionization and streamer-streamer encounters. We do not observe a strong VHF radio signal during or after branching, which is confirmed by lab experiments. This indicates that the current inside a streamer discharge evolves approximately continuously during branching. On the other hand, stochastic fluctuations in streamer propagation due to Monte Carlo photoionization lead to more radio emission being emitted at frequencies of 100 MHz and above. Another process that leads to such high-frequency emission is the interaction of a streamer with a weakly preionized region, which can be present due to a previous discharge. In agreement with previous work, we observe the strongest and highest-frequency emission from streamer encounters. The amount of total energy that is radiated seems to depend primarily on the background electric field, and less on the particular streamer evolution. Finally, we present approximations for the maximal current along a streamer channel and a fit formula for a streamer's current moment.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041385","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Diagnosing Atmospheric Heating Rate Changes Using Radiative Kernels 利用辐射核诊断大气加热率变化
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-16 DOI: 10.1029/2024JD041594
Han Huang, Yi Huang
{"title":"Diagnosing Atmospheric Heating Rate Changes Using Radiative Kernels","authors":"Han Huang,&nbsp;Yi Huang","doi":"10.1029/2024JD041594","DOIUrl":"https://doi.org/10.1029/2024JD041594","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Atmospheric radiative heating rate, which manifests radiative energy convergence in the atmosphere, is a fundamental factor shaping the Earth's climate and driving climate change. Compared to the radiative energy budget at the top of atmosphere or surface, the atmospheric energy budget and heating rate are less studied due to a lack of observational constraints and diagnostic tools. Motivated by growing interest in atmospheric energy budget and to facilitate the heating rate analysis, we innovate a set of radiative kernels, which quantitatively measure the sensitivity of atmospheric heating rate to different geophysical variables. When multiplied with the changes in these geophysical variables, these kernels quantify their contributions to the heating rate change. A climate change experiment of Global Climate Models (GCMs) is used to test the application of heating rate kernels. The results indicate the radiative heating rate change simulated by GCMs can be well reproduced by the kernels, validating the kernel method. The decomposition of the heating rate changes reveals the contributing mechanisms. For example, in the tropical upper troposphere, the negative heating anomaly in a warmer climate is dominated by atmospheric temperature and water vapor. Increases in both variables intensify atmospheric thermal radiation to space, partially offset by a positive heating anomaly caused by the lifting high-cloud tops. Moreover, compared to the results corrected using the kernels, the cloud effect inferred from the radiative heating difference between clear- and all-skies (“cloud radiative heating”) has a non-negligible bias, necessitating the use of kernels to quantify the cloud-induced heating rate changes.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041594","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Machine Learning-Driven Spatiotemporal Analysis of Ozone Exposure and Health Risks in China 机器学习驱动的中国臭氧暴露与健康风险时空分析
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-16 DOI: 10.1029/2024JD041593
Chendong Ma, Jun Song, Maohao Ran, Zhenglin Wan, Yike Guo, Meng Gao
{"title":"Machine Learning-Driven Spatiotemporal Analysis of Ozone Exposure and Health Risks in China","authors":"Chendong Ma,&nbsp;Jun Song,&nbsp;Maohao Ran,&nbsp;Zhenglin Wan,&nbsp;Yike Guo,&nbsp;Meng Gao","doi":"10.1029/2024JD041593","DOIUrl":"https://doi.org/10.1029/2024JD041593","url":null,"abstract":"<p>Accurate and fine-scaled prediction of ozone concentrations across space and time, as well as the assessment of associated human risks, is crucial for protecting public health and promoting environmental conservation. This paper introduces NetGBM, an innovative machine-learning model designed to comprehensively model ozone levels across China's diverse topography and analyze the spatiotemporal distribution of ozone and exposure. Our model focuses on daily, weekly, and monthly predictions, achieving commendable <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{R}}^{2}$</annotation>\u0000 </semantics></math> coefficients of 0.83, 0.77, and 0.79, respectively. By constructing a gridded map of ozone and incorporating both land use and meteorological features into each grid, we achieved ozone prediction at a high spatiotemporal resolution, outperforming previous research in terms of performance and scale, particularly in regions with limited monitoring stations. The results can be further improved when applied to regional research using meteorological and ozone data from regional stations. Additionally, our research revealed that temperature is the most significant factor affecting ozone concentrations across China. In health risk assessment, we retrieved a high-resolution spatial distribution of ozone-attributed mortality for 5-COD and daily ozone inhalation distributions during our study period. We concluded that ozone-attributed mortality is predominantly caused by stroke and IHD, accounting for more than 70% of the total deaths in 2021, with the highest mortality rates in developed urban areas such as the NCP and the YRD. Our experiment demonstrated the potential of NetGBM in robustly modeling ozone across China with high spatiotemporal resolution and its applicability in measuring associated health risks.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041593","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Electromagnetic Model of K-Changes K 型变化的电磁模型
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-15 DOI: 10.1029/2023JD040503
Petr Kašpar, Thomas Marshall, Maribeth Stolzenburg, Ivana Kolmašová, Ondřej Santolík
{"title":"Electromagnetic Model of K-Changes","authors":"Petr Kašpar,&nbsp;Thomas Marshall,&nbsp;Maribeth Stolzenburg,&nbsp;Ivana Kolmašová,&nbsp;Ondřej Santolík","doi":"10.1029/2023JD040503","DOIUrl":"https://doi.org/10.1029/2023JD040503","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>K-changes are observed as step-like increases in the thundercloud electric fields. The K-changes occur in the late part of intra-cloud lightning or during negative cloud-to-ground lightning between return strokes. It has been shown that the processes leading to K-changes initiate in the decayed part of a positive leader channel and propagate toward the flash origin. They are often accompanied by microsecond-scale electric field pulses. We introduce a new model to simulate processes leading to the K-changes in cloud-to-ground lightning. Our method is based on the full solution of Maxwell's equations coupled to Poisson's equation for the thundercloud charge structure. To model the K-changes, we gradually increase the decayed channel conductivity. The modeled current wavefront propagates due to the K-processes downward along a vertical channel and completely attenuates before reaching the ground. We derive the evolution of the linear charge densities and the scalar electric potential along the channel leading to K-changes. We model electrostatic step-like changes in the measured electric field together with the approximate rates and amplitudes of the microsecond scale pulses. Step-like changes increase their amplitudes with the length of the simulated channel and with a higher conductivity of the channel. The microsecond-scale pulse waveshapes depend mainly on the propagation velocity of the current wave, and the time scale of the conductivity increase. We show that our modeled waveforms are in a good agreement with observations conducted in Florida.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142435715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Inferring Surface NO2 Over Western Europe: A Machine Learning Approach With Uncertainty Quantification 推断西欧地表 NO2:带有不确定性量化的机器学习方法
IF 3.8 2区 地球科学
Journal of Geophysical Research: Atmospheres Pub Date : 2024-10-15 DOI: 10.1029/2023JD040676
Wenfu Sun, Frederik Tack, Lieven Clarisse, Rochelle Schneider, Trissevgeni Stavrakou, Michel Van Roozendael
{"title":"Inferring Surface NO2 Over Western Europe: A Machine Learning Approach With Uncertainty Quantification","authors":"Wenfu Sun,&nbsp;Frederik Tack,&nbsp;Lieven Clarisse,&nbsp;Rochelle Schneider,&nbsp;Trissevgeni Stavrakou,&nbsp;Michel Van Roozendael","doi":"10.1029/2023JD040676","DOIUrl":"https://doi.org/10.1029/2023JD040676","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Nitrogen oxides (NO<sub>x</sub> = NO + NO<sub>2</sub>) are of great concern due to their impact on human health and the environment. In recent years, machine learning (ML) techniques have been widely used for surface NO<sub>2</sub> estimation with rapid developments in computational power and big data. However, the uncertainties inherent to such retrievals are rarely studied. In this study, a novel ML framework has been developed, enhanced with uncertainty quantification techniques, to estimate surface NO<sub>2</sub> and provide corresponding data-induced uncertainty. We apply the Boosting Ensemble Conformal Quantile Estimator (BEnCQE) model to infer surface NO<sub>2</sub> concentrations over Western Europe at the daily scale and 1 km spatial resolution from May 2018 to December 2021. High NO<sub>2</sub> mainly appears in urban areas, industrial areas, and roads. The space-based cross-validation shows that our model achieves accurate point estimates (<i>r</i> = 0.8, <i>R</i><sup>2</sup> = 0.64, root mean square error = 8.08 μg/m<sup>3</sup>) and reliable prediction intervals (coverage probability, PI-50%: 51.0%, PI-90%: 90.5%). Also, the model result agrees with the Copernicus Atmosphere Monitoring Service (CAMS) model. The quantile regression in our model enables us to understand the importance of predictors for different NO<sub>2</sub> level estimations. Additionally, the uncertainty information reveals the extra potential exceedance of the World Health Organization (WHO) 2021 limit in some locations, which is undetectable by only point estimates. Meanwhile, the uncertainty quantification allows assessment of the model's robustness outside existing in-situ station measurements. It reveals challenges of NO<sub>2</sub> estimation over urban and mountainous areas where NO<sub>2</sub> is highly variable and heterogeneously distributed.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"129 20","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JD040676","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142435354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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