Journal of Atmospheric and Solar-Terrestrial Physics最新文献

{"title":"Study of ionospheric response to an intense geomagnetic storm of 26 August 2018 over low latitudes and polar regions","authors":"Uma Pandey ,&nbsp;Sanjay Kumar ,&nbsp;Javed N. Malik ,&nbsp;A.K. Singh","doi":"10.1016/j.jastp.2025.106528","DOIUrl":"10.1016/j.jastp.2025.106528","url":null,"abstract":"<div><div>During, the minimum phase of Solar Cycle 24, an intense geomagnetic storm occurred on August 26, 2018. This storm is significant not only because of its extremely high magnetic activity but also due to its great impact on the geo-magnetosphere. The aim of this paper is to distinguish the response of the equatorial/low latitude ionosphere to geomagnetic storms from those observed in the polar ionosphere. The ionospheric response to this storm has been investigated using 14 GPS receivers at the low latitudes and polar regions in the Asian and Antarctic sectors. Analysis of GPS-TEC data during the geomagnetic storm found both positive and negative storm effects over low and polar latitudes. The enhancement in VTEC data before the commencement of the geomagnetic storm is observed over all the stations at low latitude and polar regions, which is attributed to the pre-storm solar-induced events like CMEs, and proton events. Observed geomagnetic storm effects at different longitude sectors, whether it is positive or negative, are discussed using prompt penetration of electric field, disturbance dynamo electric field, neutral wind composition changes, and storm-induced wind lifting effects. During the recovery phase on 27–28, August the positive storm effect is noticed in daytime hours at equatorial/low latitude stations, whereas the negative storm effect as in the polar region.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106528"},"PeriodicalIF":1.8,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144124936","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":"Further evidence on the predictability of long-term solar activity: Tests using new data reconstructions","authors":"Gordon Reikard","doi":"10.1016/j.jastp.2025.106541","DOIUrl":"10.1016/j.jastp.2025.106541","url":null,"abstract":"<div><div>It has been understood for some time that radionuclides can be used to reconstruct long-term solar activity. Recently, new reconstructions have become available, spanning the interval from 6755 BC to the late nineteenth century. This can be spliced together with actual sunspot data to create a continuous series for sunspots at a decadal resolution. While the timing of minima and maxima are comparable to prior estimates, the new reconstruction implies higher overall solar activity and less trending. Forecasting experiments are run over horizons of 10–80 years using regressions, combinations of regressions and neural networks, and support vector machines. Despite the differences between the new and prior reconstructions, the findings are essentially the same as in earlier studies. Long-term solar variations do not exhibit regular periodicities. While cycles can be identified using spectral analysis, these are not confirmed in the time domain. The autocorrelation function and regressions on lags show no evidence of cycles at lower frequencies. In the experiments run here, the models generally predict well up to 30 years. At 40 years, forecast accuracy begins to deteriorate. At horizons of 50–80 years, the models either converge to the mean of the data or replicate recent fluctuations with a lag. Based on the results, solar activity is essentially stochastic and cannot be predicted by time series or artificial intelligence models beyond horizons of a few decades.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106541"},"PeriodicalIF":1.8,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144115336","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":"Analysis of temporal and spatial distribution of CG lightning activity and its relationship with terrain features around Jiuxianshan mountain","authors":"Biao Zhu ,&nbsp;Binbin Lin ,&nbsp;Bing Liu ,&nbsp;Hengyi Liu","doi":"10.1016/j.jastp.2025.106546","DOIUrl":"10.1016/j.jastp.2025.106546","url":null,"abstract":"<div><div>The study analyzes the Cloud-to-Ground (CG) lightning location data of the Lightning Monitoring System in Fujian Province from 2015 to 2021. It focuses on examining the temporal and spatial distribution of CG lightning activity within a 20 km radius surrounding the Jiuxianshan meteorological station in a mountainous area. Additionally, it investigates the influence of altitude, slope, and slope aspect on the distribution of CG flash, as well as the characteristics of the current intensity distribution of return stroke. The results indicate a notable difference in the distribution of ±CG flashes. Negative CG lightning activity in the surrounding areas of the meteorological station predominantly concentrates on the northwest and southeast directions of the station, and is most concentrated during the period from 13:00 to 20:00. The distribution of return stroke current intensity exhibits an unimodal pattern, with the intensity mostly distributed within the range of 10–40 kA, accounting for 76.5 %. Among them, the proportion of cases distributed between 10 and 20 kA is the highest, reaching 35.9 %. The analysis considering terrain information reveals a generally positive correlation between the distribution density of negative CG flashes and the slope. The negative CG density is higher on east-facing and southeast-facing slopes.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106546"},"PeriodicalIF":1.8,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144106387","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":"Investigating the impact of solar flares on the geomagnetic field at Resolute Bay in 2012: A comparative statistical analysis","authors":"V.S. Gopika ,&nbsp;V. Blessy ,&nbsp;V.A. Asha ,&nbsp;N. Ankitha ,&nbsp;P. Syamily ,&nbsp;S. Amrutha ,&nbsp;B.C. Sibi ,&nbsp;S. Lekshmi ,&nbsp;C. Jim ,&nbsp;U. Rekha ,&nbsp;M.J. Tiju ,&nbsp;A. Abraham","doi":"10.1016/j.jastp.2025.106544","DOIUrl":"10.1016/j.jastp.2025.106544","url":null,"abstract":"<div><div>This study examines the solar flares of 2012 and their effects on geomagnetic disturbances at the high-latitude station Resolute Bay (RES). Employing the Vertical Variance (VV) method, the analysis highlights that geomagnetic field perturbations following solar flares are strongly influenced by sharp variations in the X-component of the solar wind speed, along with the solar flare X-ray flux and the Interplanetary Magnetic Field (IMF).</div><div>The characteristic nonlinearity of the solar wind-magnetosphere system makes it difficult to estimate the relative influence of the various interplanetary parameters that impact the geomagnetic activity. This work addresses this challenge by employing line-fit correlation coefficients to assess and compare the effects of the solar wind speed and solar flare flux. The findings demonstrate that fluctuations in the X-component of solar wind speed exert a greater influence on geomagnetic disturbances than variations in solar flare flux. Additionally, the role of the Z-component of the IMF in modulating geomagnetic activity is substantiated. Abrupt changes in the SW speed occurring when the IMF is southward are found to produce strong disturbances in the geomagnetic field. The study provides new insights into the dynamics of solar wind-magnetosphere coupling and advances our understanding of geomagnetic disturbances driven by solar activity.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106544"},"PeriodicalIF":1.8,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144124937","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 global circuit capacitor and two new ways of deriving the time constant of the global atmospheric electric circuit","authors":"Michael J. Rycroft ,&nbsp;Alexander P. Nickolaenko ,&nbsp;R. Giles Harrison ,&nbsp;Anna Odzimek","doi":"10.1016/j.jastp.2025.106545","DOIUrl":"10.1016/j.jastp.2025.106545","url":null,"abstract":"<div><div>Temporal smoothing of the electrical impulses generated by lightning and shower clouds occurs through the global atmospheric electric circuit (GEC); smoothing is quantified by the time constant of the GEC. Two new methods for calculating this time constant are presented. They are based a) on a novel global circuit capacitor model, rather than the Earth-ionosphere capacitor model, and b) on the concept of dielectric relaxation time of near-surface poorly conducting air. The new GEC model considers the contributions of stratus clouds and their changes to the electrical conductivity of the air. Using model a), the time constants for the various regions of the atmosphere, over land and oceans, are obtained and the GEC time constant is found to be ∼10 min. This compares very favourably with the time constant derived from recent observations of the effects of sudden volcanic lightning on the GEC. The upper “pseudo-electrode” of the capacitor, the actual value of whose constant potential varies according to the conditions present, is found to be at an altitude of 1.8 km. For model b), the upper pseudo-electrode is placed at the boundary between dielectric and conducting atmospheres, i.e. where the displacement current equals the conduction current. Its altitude is 2.0 km, in the vicinity of stratiform clouds; the GEC time constant is 7.6 min. The vertical profile of air conductivity which best fits both DC GEC and AC (Schumann resonance) considerations is presented. Smoothing from the GEC's time constant provides steady background conditions for stratiform cloud edge charging which may affect their properties in the climate system; the steady conditions are also exploited biologically, e.g., by spiders and their webs. Other connections between atmospheric electricity and various living species are briefly explored.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106545"},"PeriodicalIF":1.8,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144124935","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":"Spectral observation of the 24 solar terms on the Qinghai–Tibet Plateau: A case study of Lhasa, Tibet","authors":"Yi Zhou,&nbsp;Yanxia Zhou,&nbsp;Linjiang Li,&nbsp;Nuo Sang","doi":"10.1016/j.jastp.2025.106543","DOIUrl":"10.1016/j.jastp.2025.106543","url":null,"abstract":"<div><div>Twenty-four solar terms, which were created by farmers in ancient China, are based on the Earth's orbit around the Sun and reflect the changes in climate, natural phenomena, agricultural production and other aspects of human life. In this study, we conducted observations and analysed the solar spectrum of the 24 solar terms in Lhasa, Qinghai–Tibet Plateau using a high-precision solar irradiance metre. The objective was to investigate the relationship between solar radiation variations and geophysical processes in the Qinghai–Tibet Plateau region. The results showed that during the period from the Autumnal Equinox on September 23, 2022 to the Qingming Festival on April 5, 2023, the lowest environmental humidity was only 4.7 %. The impact of the atmospheric water vapor and clouds on solar radiation was relatively small, and the solar spectrum exhibited good regularity. However, during the remaining solar terms, the solar spectrum exhibited fluctuations caused by temperature, humidity and other factors. Among the 24 solar terms in Lhasa during the Summer Solstice in 2022 and 2023, the peak values of monochromatic light were 2.53 W m⁻²·nm⁻¹ and 2.71 W m⁻²·nm⁻¹, respectively, considering the combined effects of sunlight reflection and scattering caused by discrete clouds. These values exceed the peak value of the AM0 monochromatic light. By comparing the Fraunhofer lines during the ‘Two Equinoxes and Two Solstices’ in Lhasa, the absorption peaks of the Fe, Ca, H, Mg, Na and O elements were observed at wavelengths of 358 nm, 431 nm, 486 nm, 517 nm, 589 nm and 687 nm, respectively. These results provide a foundation for further investigation of solar radiation variations on the Qinghai–Tibet Plateau and their impact on the Earth and can be used as a reference for sustainable research in the Qinghai–Tibet Plateau region of China.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106543"},"PeriodicalIF":1.8,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144088856","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 rotational temperatures with a multi-wavelength photometer from the Indian equatorial station Tirunelveli","authors":"Sukanta Sau ,&nbsp;S. Gurubaran ,&nbsp;V.L. Narayanan ,&nbsp;Dupinder Singh ,&nbsp;S. Sripathi ,&nbsp;A.P. Dimri","doi":"10.1016/j.jastp.2025.106542","DOIUrl":"10.1016/j.jastp.2025.106542","url":null,"abstract":"<div><div>A multi-wavelength photometer (MWP) was operated at the equatorial station Tirunelveli (8.7°N, 77.8°E geographic), India, to study different nightglow emissions. In the present work, the intensities of the P1(2) and P1(4) lines of the OH(6,2) Meinel band were used to derive rotational temperatures in the mesosphere-lower thermosphere (MLT) region during February–April 2015. The methodology adopted to derive rotational temperatures using the MWP data is discussed in detail. A comparison with temperatures measured by the Sounding of the Atmosphere by Broadband Emission Radiometry (SABER) instrument onboard NASA's TIMED satellite was performed to validate the MWP-derived rotational temperatures. An excellent correlation was observed between the MWP-derived and SABER temperatures, with a mean temperature difference of ∼15 K. The plausible reasons for this temperature bias are discussed in this work. In addition, the P1 line intensities of the OH(6,2) band and temperatures obtained with the MWP were compared with the OH broadband intensity acquired by a co-located all-sky airglow imager (ASAI). Furthermore, the local time variation of the MWP-derived temperatures was studied, and the results were compared with the NRLMSISE-00 model simulation. This study demonstrates the effectiveness of the MWP in measuring MLT temperatures and highlights the importance of multi-instrument comparisons for validating the temperatures and airglow intensity.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106542"},"PeriodicalIF":1.8,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131363","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":"Propagation of whistler-mode waves transmitted by the DSX satellite","authors":"Anatoly V. Streltsov ,&nbsp;Jay M. Albert ,&nbsp;Michael J. Starks","doi":"10.1016/j.jastp.2025.106530","DOIUrl":"10.1016/j.jastp.2025.106530","url":null,"abstract":"<div><div>Experiments consisting of the transmission and receiving of ELF (300-3000 Hz) whistler-mode waves were conducted on board of DSX satellite. In several events, the transmitted waves were received by the same antenna on the satellite after a time delay of several hundred milliseconds. These events suggest that the transmitted waves propagate mostly along the ambient magnetic field, reflect at some location along their path, and return back to the satellite. The main questions related to these observations are: (1) What causes the guiding of the waves along the ambient magnetic field? and (2) Where in the magnetosphere are these waves reflected? The results from analytical and numerical studies presented in this paper indicate that the waves are guided by the field-aligned density inhomogeneities (aka ducts), and they are reflected from the ends of the duct.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"272 ","pages":"Article 106530"},"PeriodicalIF":1.8,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070337","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 role of geomagnetic storm-induced energetic particle precipitations in the modification of the ionosphere over the American and African longitudinal sectors","authors":"B.A. Ojapinwa,&nbsp;E.O. Oyeyemi,&nbsp;A.O. Akala","doi":"10.1016/j.jastp.2025.106539","DOIUrl":"10.1016/j.jastp.2025.106539","url":null,"abstract":"<div><div>Geomagnetic storms are associated with changes in electron and proton fluxes in the radiation belts, leading to precipitation. However, most past studies have been done based on storms’ intensities. This study investigates the roles of eight geomagnetic storms, classified by their intensities using Dst threshold conditions, and interplanetary drivers, in the production of Energetic Particle Precipitation (EPP), and their subsequent modification of ionospheric irregularities and Total Electron Content (TEC). We used energetic particle fluxes, TEC, interplanetary magnetic field, and solar wind data. The rate of TEC index (ROTI) was used as a proxy for ionospheric irregularities. In this study, the ability of a storm to induce EPPs is predominant and significant during the recovery phases of storms. Consequently, the modifications of the ionosphere caused by EPPs were mostly pronounced during the recovery phase of a storm. At the recovery phases, enhanced EPPs induced by intense sheath (SH)- and Corotating Interaction Region (CIR)-driven storms caused corresponding enhancements in TEC and ionospheric irregularities, while that of intense magnetic cloud (MC)-driven storm showed no significant effect on TEC and irregularities. Furthermore, enhanced EPP induced by intense and moderate MC + SH-driven storms caused little or no change in TEC and ionospheric irregularities. In addition, an enhanced EPP induced by moderate sheath- and MC-driven storms caused depletion in TEC and irregularities. Irregularities were more prevalent at the low- and high-latitude, but less in occurrences at the mid-latitude in the African sector. Overall, from this study, the African sector responded more to the energetic particles than the American sector. Irregularities at the high-latitude stations were generally high and frequent regardless of the phase, magnitude, driver, or local times of occurrence of storms. The storm-induced EPP enhancements were more significant in the southern hemisphere than in the northern hemisphere, and the events of the equinoctial months showed more dependence on EPPs.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"273 ","pages":"Article 106539"},"PeriodicalIF":1.8,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144083609","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 importance of electric field or/and neutral wind in formation and prediction of sporadic E (Es) at the equatorial and mid-latitude regions","authors":"Goderdzi G. Didebulidze ,&nbsp;Giorgi Dalakishvili ,&nbsp;Maya Todua ,&nbsp;Lekso Toriashvili","doi":"10.1016/j.jastp.2025.106540","DOIUrl":"10.1016/j.jastp.2025.106540","url":null,"abstract":"<div><div>This study investigates the formation and localization of sporadic E(Es) at equatorial and mid-latitude regions in case of presence of electric field or/and neutral wind. It has been shown that at the equatorial region, in analogy to the mid-latitude regions, the necessary condition for development of ion vertical convergence and formation of sporadic E (Es) is the presence of the minimal negative value of ion drift velocity divergence in its height profile (including only a vertical component). This condition at the equatorial region is significantly determined by the neutral wind velocity and the zonal and vertical components of the electric field, even when this field is homogeneous. The ions vertical convergence developed in these regions and the formation of the Es layer can take place against the background of their upward or downward drift. Sporadic layer localizes either at the node of the ions drift velocity, or in the regions where this velocity disappears. The formation and dynamics of Es layers are demonstrated by numerical methods which makes possible its prediction. The effects of the zonal and vertical components of the electric field, as well as the wind velocity (determined by the HWM14 data), on the processes of ion convergence/divergence development, at equatorial and mid-latitudes, are shown. In these cases, the ion convergence/divergence, induced by the electric field, can affect both the formation and disruption (depletion) of the Es layer formed by neutral wind, and can also increase its density or/and form an additional layer. It is also shown that the presence of electric field, along with the meridional and zonal wind at mid-latitudes, can affect both the formation and the behavior of Es layers at these regions.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"272 ","pages":"Article 106540"},"PeriodicalIF":1.8,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070338","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}