Journal of Atmospheric and Solar-Terrestrial Physics最新文献

{"title":"On the retrieval of particle size information of noctilucent clouds from optical remote sensing measurements","authors":"Christian von Savigny","doi":"10.1016/j.jastp.2025.106447","DOIUrl":"10.1016/j.jastp.2025.106447","url":null,"abstract":"<div><div>Noctilucent clouds (NLCs) are optically thin ice clouds occurring near the polar mesopause in the summer hemisphere. Our understanding of the particle size of NLCs is to a large extent based on optical measurements in different observation geometries and optical NLC particle size retrievals are always based on a priori assumptions on the shape of the particle size distribution. The actual shape of the particle size distribution is generally not well known and can be assumed to be highly variable. In addition, the scattering cross section of NLC particles depends strongly on particle size. This leads to effects that have until now not been considered properly in the literature, i.e. if the assumed shape of the particle size distribution differs from the actual one, NLC size retrievals based on different measurement techniques will be associated with different biases. These differences can be quite substantial, for the retrieved particle number density in particular. In this study we carry out NLC particle size retrievals based on simplified synthetic forward simulations for the following observation techniques: satellite occultation, satellite limb-scatter, ground-based lidar and satellite nadir measurements. For the forward simulations we assume a bi-modal particle size distribution, while for the size retrieval a mono-modal distribution is assumed — which is typically the case in the literature. We assume both normal and log-normal particle size distributions, but the main results of this study are independent of the specific assumption on the shape of particle size distribution. We find that even for small deviations from the assumed shape of the particle size distribution, relatively large differences in retrieved size estimates occur between the different observation geometries considered. The retrieved median radii can differ by up to a factor of 2, while retrieved particle number densities can differ by more than a factor of 10 between the different observation geometries. These results need to be considered when comparing NLC size retrievals from different optical techniques.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106447"},"PeriodicalIF":1.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ionospheric disturbances over Ukraine through the eyes of standalone GNSS receiver","authors":"Sayak Ray ,&nbsp;Batakrushna Senapati ,&nbsp;Bhaskar Kundu ,&nbsp;M. Santosh","doi":"10.1016/j.jastp.2025.106451","DOIUrl":"10.1016/j.jastp.2025.106451","url":null,"abstract":"<div><div>The atmospheric waves generated from large-scale natural phenomena such as earthquakes, volcanoes, and anthropogenic explosions propagate upward to the upper atmosphere and cause perturbations in the ionosphere. In the present study, we investigate the ionospheric perturbations in terms of total electron content (TEC) signatures induced by the missile/airstrikes over the Ukraine region during the ongoing Russian-Ukrainian conflict, which has been captured through a standalone ground-based Global Navigation Satellite System (GNSS) receiver. We observed an ionospheric electron content change of ∼0.1–0.3 TECU caused by the acoustic wave generated from the missile/air strikes. We also noticed a strong directivity of the ionospheric disturbances over Ukraine, with maximum ionospheric disturbances in the south direction from the epicenter of the events. Further, the ionospheric disturbance's peak-to-peak amplitude was 1.5% of the background electrons, slightly less than the magnitude of volcanic eruptions in the Islands of Japan.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"268 ","pages":"Article 106451"},"PeriodicalIF":1.8,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143270165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is heating of ions by Alfvén waves via nonresonant interactions applicable in the Earth’s magnetosphere?","authors":"I.A. Barghouthi,&nbsp;W.T. Rabai","doi":"10.1016/j.jastp.2024.106413","DOIUrl":"10.1016/j.jastp.2024.106413","url":null,"abstract":"<div><div>Heating of ions in Earth’s magnetosphere by enhanced Alfv<span><math><mover><mrow><mi>e</mi></mrow><mrow><mo>́</mo></mrow></mover></math></span>n waves below resonance frequency (nonresonant heating) has been presented in many studies, among these is the study of Wang et al. (2006) in which they stated that in any region in space with low beta plasma, this heating process, i.e. nonresonant ion heating is applicable and effective. In this paper we stress on the inapplicability of this type of heating in the Earth’s magnetosphere. We present; (1) a data set that provides a strong proof that the theory presented by Wang et al. (2006) is not applicable in this region of space (i.e. Earth’s magnetosphere), (2) in addition, we plot altitude profiles for parallel, perpendicular, and total temperatures for hydrogen ions in cusp and central polar cap regions by evaluating observed magnetic activity and Alfv<span><math><mover><mrow><mi>e</mi></mrow><mrow><mo>́</mo></mrow></mover></math></span>n waves into Wang et al. (2006) theory, we find the changes in the altitude behavior in ion temperature profiles are very small, (3) also, we compare between Monte Carlo simulations results of ion temperatures obtained by using Barghouthi model (this model includes the effects of gravity, polarization electric field, divergence geomagnetic field, centrifugal acceleration, resonant ion heating, and with and without nonresonant ion heating effect) in cusp and central polar cap regions with appropriate boundary conditions (Barghouthi et al., 2008), both simulation results of ion temperatures are almost the same. Therefore, we report on the nonresonant ion heating process in central polar cap and cusp regions is not significant.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106413"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate time series variability analysis of Islamabad Capital Territory using fractal dimension and Hurst exponent methods","authors":"Ali Khan ,&nbsp;Shahid Hussain ,&nbsp;Ahmed Bakhet ,&nbsp;Afshan Anwer ,&nbsp;S.M. Murshid Raza ,&nbsp;Sajjad Ali ,&nbsp;Mohammed Zakarya","doi":"10.1016/j.jastp.2024.106406","DOIUrl":"10.1016/j.jastp.2024.106406","url":null,"abstract":"<div><div>This study is an attempt to examine variability of climatic parameters at local scale, Islamabad Capital Territory (ICT). Climate change can affect temperature trends and precipitation patterns, horticultural activity, agricultural productivity, underground water level, portable water availability, and infrastructure.To assess the impact of climate change of Islamabad Capital Territory, the data of precipitation, minimum and maximum temperatures were obtained for the period from 1983 to 2022 from Pakistan Metrological Department (PMD). Fractal dimension <em>D</em> and Hurt exponent <em>H</em> methods were employed to estimate the monthly maximum and minimum temperatures, and precipitation of the study area. The data was portioned into 4 subsets. Rescaled range analysis method was applied on the datasets to compute values of Hurst exponent and fractal dimension. The results obtained show Brownian random and persistent tendencies, correspondingly. On the other hand, the period from 2013 to 2022 shows anti-persistent trend for H and random trend during (2013–2022) for D, respectively. The time series showing persistent results contain the long-term memory. When a time series shows random Brownian behaviour, thenthere will be no any extended long-term memory. Rescaled range analysis (<em>R/S</em>)method was employed to compute fractal dimensions show consistent outcomes, reveal small fluctuation in the local behaviour of minimum temperatures.Whereas, Hurst exponent values of maximum temperatures show random behavior i.e. there exists no correlation. The Hurst exponents computed confirm persistent results for precipitation pattern. Likewise, the computed values of fractal dimensions also show persistent results. Thus, the precipitation pattern shows cyclic behaviour, i.e. the precipitation time series retain long-run memory. Finally, from the persistent behavior of time series, one would infer that there will bean extended time effect on the local precipitation pattern. Python software was used to perform computations.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106406"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical investigations on the reactions of CH3CH2NCH3 radicals in the presence of NO, NO2 and O2","authors":"Fei Liu ,&nbsp;Chenggang Lu ,&nbsp;Yizhen Tang ,&nbsp;Yaru Pan","doi":"10.1016/j.jastp.2025.106420","DOIUrl":"10.1016/j.jastp.2025.106420","url":null,"abstract":"<div><div>The reactions of CH₃CH₂NCH₃ amino radicals in the presence of NO, NO₂ and O₂ were investigated by quantum chemistry methods. It was found that CH₃CH₂N(CH₃)NO, CH₃CH₂N(CH₃)NO₂ and CH₃CH₂N(CH₃)ONO can be formed dominantly when CH₃CH₂NCH₃ reacts with NO and NO₂, while CH₃CH=NCH₃ and CH₃CH₂N=CH₂ will be feasible when CH₃CH₂NCH₃ is in the presence of oxygen. Time dependent density functional theory (TDDFT) calculation shows that CH₃CH₂N(CH₃)NO and CH₃CH₂N(CH₃)ONO can photolyze under the sunlight, while CH₃CH₂N(CH₃)NO₂ cannot undergo photolysis in the daytime. Comparisons among the reactions of (CH₃)₂N, (CH₃CH₂)₂N and CH₃CH₂NCH₃ with NO, NO₂ and O₂ indicate that the asymmetric substituted alkyl groups will play a notable role in the formation of stable products.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106420"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 vertically time-dependent aerosol effect on marine water clouds","authors":"Hui Lu ,&nbsp;Hui Zhao ,&nbsp;Kanike Raghavendra Kumar ,&nbsp;Honglin Pan","doi":"10.1016/j.jastp.2025.106453","DOIUrl":"10.1016/j.jastp.2025.106453","url":null,"abstract":"<div><div>The aerosol-cloud interactions importantly influence the energy and water cycle of Earth-atmosphere system. The uncertainty of climate models is partly due to the lack of large-scale observational constraints of interaction between aerosol and water cloud. Based on CATS lidar time-resolved observations over the global marine region during 2015–2017, this study investigates the vertical effect of aerosol on marine water clouds, and evaluates the covariate influence of meteorological factors combined with European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis meteorological data. The mutual roles between aerosols as cloud condensation nucleation (CCN) and meteorological variables (temperature and relative humidity) contribute to the non-linear relationship of interactions between aerosol and water clouds. The results provide effective constraints for the parameterizations of aerosol-cloud interactions in current climate models.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"269 ","pages":"Article 106453"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143418888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Total electron content at an equatorial station during low solar activity: Geomagnetic activity effects emphasis","authors":"Sarvesh Kumar ,&nbsp;Sushil Kumar","doi":"10.1016/j.jastp.2024.106415","DOIUrl":"10.1016/j.jastp.2024.106415","url":null,"abstract":"<div><div>The initial results of Total Electron Content (TEC) data from September 2017 to November 2018 recorded over an equatorial station, Tarawa (geographic: 1.33°N, 173.01°E, geomagnetic: 2.68°S, 114.26°W) are presented which showed diurnal TEC maxima between 15:00–14:00 LT. The seasonal and semi-annual variations in the VTEC are clear, along with the less occurring winter anomalies and TEC bite-outs. The VTEC on magnetically disturbed days was higher than on quiet days. VTEC response to seven geomagnetic storms (5 moderate and 2 intense) showed positive ionospheric effect by all storms during their main phase. The VTEC response to two selected geomagnetic storms of 7–8 November 2017 (moderate strength, <em>Dst</em> = −72 nT) and 25–26 August 2018 (intense strength, <em>Dst</em> index = −174 nT) has been presented. During the November storm, TEC decreased by about 25.6% during the first step development of the main phase and increased by approximately 26.2% during the second step of main phase development. A long duration (&gt;24 h) increase in VTEC of about 47.3% was found during the main phase of the August storm. VTEC changes during the main phase of both storms are due to the storm-time auroral prompt penetrating electric field, while the disturbance dynamo electric field produced negative ionospheric effects during their recovery phases as indicated by changes in equatorial electrojet values obtained from SWARM A, B, and C satellites and <em>AE</em> index, respectively. The global O/N₂ gas data from the Global Ultraviolet Imager (GUVI) onboard TIMED spacecraft show that O/N₂ changes, to a lesser extent, were also responsible for the geomagnetic storm effects observed at our station.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106415"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of separation in junction frequency in vertical incidence ionogram traces observed at low-mid latitude Indian station, New Delhi: Ionosonde observations","authors":"Arti Bhardwaj ,&nbsp;Anshul Singh ,&nbsp;Qadeer Ahmed ,&nbsp;Ankit Gupta ,&nbsp;A.K. Upadhayaya","doi":"10.1016/j.jastp.2024.106414","DOIUrl":"10.1016/j.jastp.2024.106414","url":null,"abstract":"<div><div>Ionogram traces split into two modes, ordinary (O) and extraordinary (X), in the F-layer due to magneto-ionic splitting, where a transmitted pulse propagates in two distinct ways under the influence of Earth's magnetic field. The Earth's magnetic field causes ionogram traces to show double hop echoes when an echo is reflected back upward by the ground and then re-reflected by the ionosphere, demonstrating that the ionosphere is a doubly refracting medium. We have investigated the separation in Junction frequencies (JFs) of the O and X modes in vertical incidence ionogram traces observed over a seven-year period (2014–2020) during the declining phase of the solar cycle, from maximum to minimum. This difference in splitting in two modes is expected to be 0.67 MHz at low-mid latitude Indian station, New Delhi (28.6°N, 77.2°E). Anomalous separations of more than 21% in JFs were observed during the analysis. In these cases, we found over 30% anomalous cases of JFs in different seasons, with the highest occurrence in summer, followed by equinox and winter. JFs followed diurnal variation, with heightened variation during the solar cycle maxima and minimal variation during solar cycle minima. Lastly, we observed a concurrency between JFs and ionospheric perturbations caused by phenomena originating in both the lower and upper atmosphere.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106414"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel hybrid solar radiation forecasting algorithm based on discrete wavelet transform and multivariate machine learning models integrated with clearness index clusters","authors":"Burak Arseven,&nbsp;Said Mahmut Çınar","doi":"10.1016/j.jastp.2025.106417","DOIUrl":"10.1016/j.jastp.2025.106417","url":null,"abstract":"<div><div>This study presents an innovative forecasting algorithm that combines multivariate regression (MR) and discrete wavelet transform (DWT) techniques with clearness index (CI)-based clustering methods to enhance short-term (1 h ahead) solar radiation forecasting. The proposed algorithm consists of two main steps: the first involves forecasting processes using DWT and MR methods, while the second includes clustering processes determined based on CI values. In the forecasting process, the data has been decomposed into sub-signals at different levels using DWT first. Multivariate ridge regression (MRR) and lasso regression (MLR) models for the sub-signals have been determined based on input training data sets created from three different combinations of these sub-signals. Sub-forecast signals have been obtained using models that were determined in different formats. The sub-forecast signals obtained have been recombined using the DWT reconstruction to produce the final forecasts. In the clustering process, clusters have been formed based on CI values using the Kernel k-means algorithm, which has been identified as the most effective among three different algorithms. The effectiveness of forecasts generated using DWT-MRR and DWT-MLR models for all input data set versions has been evaluated within the CI-based clusters.</div><div>The study's key findings have revealed that decomposition at the first level of DWT is sufficient to achieve optimal forecasting performance. Furthermore, the input variables yielding the best results have differed across clusters: radiation and relative humidity for the mostly cloudy cluster, radiation, temperature, and relative humidity for the cloudy cluster, and radiation and temperature for the slightly cloudy cluster. The results have demonstrated that the proposed algorithm achieves a 17% improvement in root mean square error (RMSE) compared to the best-performing model developed without CI clustering. The proposed approach significantly contributes to the literature by optimizing DWT decomposition levels, adapting data modeling to cloudiness conditions, and integrating multiple forecasting techniques to improve performance.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106417"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interpretable artificial intelligence models for predicting lightning prone to inducing forest fires","authors":"Sida Song ,&nbsp;Xiao Zhou ,&nbsp;Shangbo Yuan ,&nbsp;Pengle Cheng ,&nbsp;Xiaodong Liu","doi":"10.1016/j.jastp.2024.106408","DOIUrl":"10.1016/j.jastp.2024.106408","url":null,"abstract":"<div><div>Specific types and intensities of lightning are significant causes of forest lightning fires. Analyzing the relationship between these lightning events and the climatic conditions that favor their occurrence is crucial for predicting and preventing forest lightning fires. However, there is a lack of research in this area for the Greater Khingan Range in Northeast China. This study utilized data from three lightning location networks and the ERA5 meteorological dataset to analyze the historical climate and lightning data in the Greater Khingan Mountains region of China from 2021 to 2023, focusing on the impact of various climatic factors on the density of target lightning—lightning that is prone to cause forest lightning fires. Four machine learning models—SVM, RF, XGBoost, and LightGBM—were evaluated, with RF demonstrating the best predictive performance, achieving R² of 0.83, MAE of 1.91, and MSE of 14.90. Additionally, the prediction results of the RF model were evaluated using the Kruskal-Wallis test to determine if the results are statistically significant. Using SHAP values to interpret the model, it was found that the K-index (kx) and Convective Available Potential Energy (CAPE) are the most significant predictors of target lightning density, followed by the leaf area index for high vegetation (lai_kv), surface pressure (sp), cloud base height (cbh), temperature at 2 m (t2m), and coverage of high vegetation (cvh). Approximately 70% of the total average absolute SHAP values are attributed to kx and CAPE, highlighting their crucial role in the prediction process. This study provides insights into the environmental factors influencing lightning frequency and emphasizes the importance of interpretable machine learning models in predicting future lightning occurrences and forest lightning fires. Visualization tools, including SHAP summary plots and force plots, were used to provide a detailed illustration of each feature's contribution to the model predictions.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"267 ","pages":"Article 106408"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}