Journal of Atmospheric and Solar-Terrestrial Physics最新文献

{"title":"Development and field testing of a UHF antenna system for the observation of electrical discharge phenomena in the atmosphere","authors":"Nobuaki Shimoji ,&nbsp;Itsuki Tofuku","doi":"10.1016/j.jastp.2026.106754","DOIUrl":"10.1016/j.jastp.2026.106754","url":null,"abstract":"<div><div>In Japan, the digital terrestrial television broadcasting band (470–710 MHz) is legally protected, resulting in extremely low levels of artificial electromagnetic noise within this frequency range. Therefore, when an antenna is directed toward targets such as cumulus clouds, high-voltage transmission towers, volcanic plumes, or trees, the received signals are highly likely to be ultra high frequency (UHF) event signals—discharge emissions—from those targets. Because discharge phenomena last only tens of nanoseconds, developing instruments capable of directly recording them is technically difficult. Considering Japan’s radio-wave environment and practical hardware constraints, we developed a UHF antenna system with a <span><math><mrow><mn>0</mn><mo>.</mo><mn>4</mn><mspace></mspace><mi>ms</mi></mrow></math></span> sampling interval. A dual-integration system was devised and implemented in the backend, enabling continuous recording with no dead time.</div><div>Although a <span><math><mrow><mn>0</mn><mo>.</mo><mn>4</mn><mspace></mspace><mi>ms</mi></mrow></math></span> interval is long relative to discharge timescales, it becomes a practical method when the objective is not to resolve individual pulses but to detect the collective occurrence of numerous discharge events. The developed system was installed outdoors, and tests confirmed reception of both discharge signals and television broadcasts. Subsequent observations included cumulus clouds, partial discharges from high-voltage transmission towers, small-scale volcanic eruptions, and tree corona discharges. For each target, characteristics consistent with streamers, corona discharges, or partial discharges were obtained. These results suggest that, although improvements are still possible, the compact UHF antenna system developed in this study has the potential to serve as a new observational method for atmospheric discharge phenomena.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106754"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420977","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":"Investigation of the GFS forecast products on RT-PPP solutions","authors":"Ali Hasan Dogan","doi":"10.1016/j.jastp.2026.106755","DOIUrl":"10.1016/j.jastp.2026.106755","url":null,"abstract":"<div><div>Tropospheric delays play a key role in Precise Point Positioning (PPP). To achieve high precise positioning, these delays must be eliminated. In PPP, a priori delays and mapping functions (MF) are used to eliminate/model tropospheric delays. It can be seen in literature that the parameters obtained from Numerical Weather Models (NWM) increase the accuracy of the positioning. In addition to post-process applications of PPP, there is an increasing need of real time precise positioning to support recent technological developments. In this study, the effects of the a priori delays and MFs on real time PPP (RT-PPP) were investigated. Therefore, a case study was designed. In the study, two simultaneous RT-PPP analysis were performed by BNC software. In the first run, default configuration of the software was used. In the second run, a priori delays and MFs obtained using NCEP's GFS forecast data were utilized. The delays and MF coefficients were derived by Direct Numerical Solution (DNS) ray-tracing tool. The effects of the parameters were compared by the parameters, convergence time, positioning and Zenith Tropospheric Delay accuracy. The results show that GFS utilized solutions converge the positions faster. Moreover, accuracy of the vertical component is also improved.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106755"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420975","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":"Impact of monsoon phases on atmospheric boundary layer dynamics over the Indian subcontinent and surrounding oceans","authors":"Linsha C.L. ,&nbsp;Hamza Varikoden ,&nbsp;Nandhulal K. ,&nbsp;Vishnu R.","doi":"10.1016/j.jastp.2026.106765","DOIUrl":"10.1016/j.jastp.2026.106765","url":null,"abstract":"<div><div>The prevailing atmospheric conditions are strongly influenced by the Atmospheric Boundary Layer Height (ABLH) over the Indian subcontinent and serve as a critical parameter in forecasting weather, climate patterns, and the distribution of pollutants. The study examines intraseasonal variations of ABLH over the Indian subcontinent and surrounding oceans using MERRA data from 1980 to 2018. ABLH is lower over marine regions during the daytime, likely due to high specific heat capacity and low surface roughness. Low marine influence causes higher diurnal variations over the inland areas than the coastal regions. In Peninsular India, a lower ABLH was associated with the orographic effects of the Western Ghats and the influence of sea-land breeze circulation. ABLH is maximum during the daytime in the break phase of the monsoon across most of India, except in the northwest and southeast regions, where lower rainfall resulted in a higher ABLH during the active phase. In marine areas, the highest ABLH was observed during the active phase. However, ABLH was elevated over the oceanic regions adjacent to Saudi Arabia and Peninsular India during the break phase, suggesting that nearby land areas impact ABLH over marine regions. Thus, the changes in ABLH during the monsoon circulations are under the control of nearby oceanic regions and vice versa. Spectral analysis revealed low variance and high periodicity in ABLH over Peninsular India, with notably low variance during the break phase. The influence of the Western Ghats and the Arabian Sea makes constant ABLH over Peninsular India with high periodicity.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106765"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422313","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":"Corrigendum to “An absolute cavity pyrgeometer to measure the absolute outdoor longwave irradiance with traceability to International System of Units, SI” [J. Atmos. Sol. Terr. Phys. 77 (2012) 132–143]","authors":"Ibrahim Reda ,&nbsp;Jinan Zeng ,&nbsp;Jonathan Scheuch ,&nbsp;Leonard Hanssen ,&nbsp;Boris Wilthan ,&nbsp;Daryl Myers ,&nbsp;Tom Stoffel","doi":"10.1016/j.jastp.2025.106679","DOIUrl":"10.1016/j.jastp.2025.106679","url":null,"abstract":"","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106679"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422314","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":"Biomass burning signatures and seasonal variations of HCN and C2H6 over Addis Ababa using ground-based FTIR spectroscopy","authors":"Ambachew Abeje Alemu ,&nbsp;Gizaw Mengistu Tsidu","doi":"10.1016/j.jastp.2026.106758","DOIUrl":"10.1016/j.jastp.2026.106758","url":null,"abstract":"<div><div>We present the first multi-year analysis of hydrogen cyanide (HCN) and ethane (C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>H<span><math><msub><mrow></mrow><mrow><mn>6</mn></mrow></msub></math></span>) over Equatorial Africa using high-resolution ground-based Fourier Transform Infrared (FTIR) solar absorption spectroscopy. Measurements were conducted from May 2009 to February 2011 at the Addis Ababa University observatory (9.01 ° N, 38.76 ° E, 2.45 km asl), a unique station in a critically under-sampled region. Vertical profiles and total column amounts were retrieved using the PROFFIT algorithm. The results reveal significant seasonal variability in both species. Total column amounts ranged from 9.83 ×10¹⁸ to 6.39 ×10¹⁹ molecules<span><math><mi>⋅</mi></math></span>cm⁻² for HCN and from 3.60 ×10¹⁹ to 1.70 ×10²⁰ molecules<span><math><mi>⋅</mi></math></span>cm⁻² for C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>H<span><math><msub><mrow></mrow><mrow><mn>6</mn></mrow></msub></math></span>, with a pronounced maximum observed in March for both gases. This seasonal peak correlates strongly with the regional biomass burning season. Vertical distributions indicate C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>H<span><math><msub><mrow></mrow><mrow><mn>6</mn></mrow></msub></math></span> is predominantly confined to the lower troposphere (<span><math><mrow><mo>&lt;</mo><mn>8</mn></mrow></math></span> km), consistent with its primary surface sources and shorter atmospheric lifetime, while HCN shows significant sensitivity extending into the upper troposphere and lower stratosphere, reflecting its longer lifetime and capacity for vertical transport. A detailed case study for a high-concentration period in March 2010, employing HYSPLIT backward trajectories and satellite fire maps, demonstrates that elevated levels of HCN and C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>H<span><math><msub><mrow></mrow><mrow><mn>6</mn></mrow></msub></math></span> over Addis Ababa were associated with long-range transport of air masses originating from and passing over intense biomass burning regions in North and Central Africa. These findings provide direct observational evidence that biomass burning is a dominant source of both HCN and C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>H<span><math><msub><mrow></mrow><mrow><mn>6</mn></mrow></msub></math></span> in this region and underscore the importance of Equatorial Africa in the global budget of these trace gases. The study highlights the role of atmospheric transport in influencing local air quality and atmospheric composition and establishes a crucial baseline for future long-term monitoring in the region.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106758"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420968","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":"Statistical study of the Thermosphere-Ionosphere Sporadic Nickel (TISNi) layers over Beijing based on lidar observations","authors":"Zhijun Zhao ,&nbsp;Yuhang Qi ,&nbsp;Fuju Wu ,&nbsp;Fang Wu ,&nbsp;Xuyang Jiang ,&nbsp;Jing Jiao ,&nbsp;Guotao Yang","doi":"10.1016/j.jastp.2026.106743","DOIUrl":"10.1016/j.jastp.2026.106743","url":null,"abstract":"<div><div>This paper reports a lidar observation study of Thermosphere-Ionosphere Sporadic Nickel (TISNi) layers through 2675 h of lidar observations at Yanqing Station, Beijing (40.42°N, 116.02°E) from April 2019 to November 2022. A total of 41 TISNi events are observed during 304 observation nights. These events are only observed from May to October, showing obvious seasonal variation. TISNi had the highest occurrence rate in May (69%). It is worth noting that the ratio of TISNi peak density to the main layer peak density exceeds 1 during May–July but drops below 1 in August–October, indicating a relatively higher abundance of Ni atoms in the thermosphere-ionosphere region during May–July. Furthermore, TISNi shows a strong correlation with Es(sporadic E layer), almost every TISNi event corresponds to Es. Based on the Speed of descending of TISNi, it is speculated that TISNi is likely formed through the neutralization of Ni⁺, which is converged by tidal winds.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106743"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147421989","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":"Modulation of basic Schumann resonance frequency by solar activity","authors":"Alexander P. Nickolaenko","doi":"10.1016/j.jastp.2026.106766","DOIUrl":"10.1016/j.jastp.2026.106766","url":null,"abstract":"<div><div>The present work treats the monthly-interannual variations of fundamental frequency of the global electromagnetic (Schumann) resonance observed in the vertical electric field component. During a year, the monthly averaged pattern &lt;<em>f</em>₁(UT)&gt; alters from month to month, but the particular outline of a given month repeats with small deviations from year to year thus reflecting the diurnal and seasonal periodicity in the dynamics of global thunderstorms. A heuristic model is derived for diurnal-seasonal-interannual variations on the basic SR frequency present in the long-term records in the Széchenyi István Geophysical Observatory (SZIGO) at Nagycenk, Hungary (47.6° N; 16.7° E). The observational data cover 192 months of continuous observations from January 1994 to December 2009. Statistical processing of records showed that interannual changes in SR frequency resemble the contemporary solar activity. The heuristic model was developed combining the standard (reference) diurnal-seasonal pattern of resonance frequency for a median year and the corrections accounting for variable solar activity relevant to a particular month and year. The model fits the observation data and accurately predicts the frequency variations using the known level of solar activity.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106766"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422312","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":"Estimation, prediction, and forecasting of urban solar brightness: A comprehensive benchmarking of empirical, hybrid AI, and Deep-NARMAX models","authors":"Youness EL Mghouchi ,&nbsp;Mihaela Tinca Udristioiu","doi":"10.1016/j.jastp.2026.106761","DOIUrl":"10.1016/j.jastp.2026.106761","url":null,"abstract":"<div><div>Understanding the variability of solar brightness is essential for optimising solar energy systems, improving urban air quality assessments, and enhancing environmental forecasting. The aim of this study is to investigate the influence of meteorological and atmospheric pollutant variables—including temperature, relative humidity, precipitation, wind direction, wind speed, PM₂.₅, PM₁₀, ozone (O₃), carbon monoxide (CO), SO₂, O₃, NO, NO₂, NO_x and others—on incoming solar radiation, using solar brightness as a proxy. A comprehensive dataset spanning five years of hourly observations was analysed. Open-source data from four air quality monitoring stations in Craiova, was provided by the Romanian Environmental Agency. The study followed a five-stage approach. First, data preprocessing was conducted to identify and address anomalies, outliers, and missing values, while trends for solar brightness and other studied variables were analysed. In the second stage, the best global solar radiation (GSR) model among 10 GSR models is selected. In the third stage, correlations between solar brightness and other variables, including data provided by the best GSR model, based on exploratory data analysis, were examined. A deep AI-based hybrid approach was applied in the fourth stage to discover the optimal AI predictive model for solar brightness based on related variables. Finally, a deep NARMAX model was elaborated and applied to model and anticipate next hourly solar brightness in Craiova. A set of statistical metrics was employed to assess the results of the models.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106761"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420971","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":"Using physical parameters in a deep neural network for regional VTEC prediction","authors":"Mohammad Alikhani ,&nbsp;Yazdan Amerian ,&nbsp;Hany Mahbuby","doi":"10.1016/j.jastp.2026.106737","DOIUrl":"10.1016/j.jastp.2026.106737","url":null,"abstract":"<div><div>Accurate prediction of Total Electron Content (TEC) is essential for satellite navigation and communication systems, as ionospheric disturbances affect signal accuracy. TEC forecasting supports the stable operation of GNSS technologies. Artificial intelligence (AI), particularly deep learning, has shown strong potential in TEC prediction by modeling complex spatiotemporal patterns. This study presents a hybrid deep learning model combining BiLSTM, CNN, and GRU to predict TEC over Iran. The training dataset consisted of 365 days of Global Ionospheric Maps (GIM) VTEC data and ionospheric parameters from the International Reference Ionosphere (IRI) during 2017, while validation used the first quarter of 2018. The year 2017 was selected to cover a wide range of geomagnetic and solar conditions, thus providing comprehensive input for model development. Input parameters included electron temperature, critical frequencies, geomagnetic indices, and solar activity indicators, enabling the model to capture both spatial and temporal dependencies. During validation on 2018 data, the model achieved an RMSE of 1.63 TECU, MAE of 1.19 TECU, NRMSE of 0.04, MAPE of 11.80%, and a correlation coefficient of 92.15%, clearly outperforming the IRI-2016 model and closely matching the GIM values. Evaluation using 2019 data, covering dates with high and low geomagnetic activity across multiple locations in Iran, demonstrated strong predictive accuracy, with RMSE of 1.35 TECU, MAE of 1.12 TECU, NRMSE of 0.10, MAPE of 9.55%, and R of 97.62%. The improvement is largely due to the inclusion of physical parameters, highlighting the robustness of the proposed model under diverse ionospheric conditions.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106737"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420976","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":"Storm-time geomagnetic variations and Pc5 activity at mid- and high-latitudes: Insights from the 20 November 2003 storm","authors":"E.M. Takla ,&nbsp;A. Yoshikawa ,&nbsp;T. Uozumi","doi":"10.1016/j.jastp.2026.106763","DOIUrl":"10.1016/j.jastp.2026.106763","url":null,"abstract":"<div><div>Geomagnetic field measurements from four mid- and high-latitude stations of the MAGDAS/CPMN network were analyzed to investigate the effects of the intense Geomagnetic Storm (GS) of November 20, 2003 on geomagnetic field variations and Pc5 pulsation activity. The results show that the geomagnetic field measurements at high-latitude stations were strongly influenced by variations in the interplanetary magnetic field (IMF) and solar wind parameters during this storm. Both the amplitude of geomagnetic fluctuations and the intensity of Pc5 activity were found to be significantly larger at polar and auroral latitudes than at mid-latitude. In particular, the occurrence and amplitude of Pc5 pulsations were greatest within the auroral zone and decreased slightly with increasing latitude poleward. The findings, consistent with previous results reported in the literature, emphasize the central role of auroral-latitude ionospheric processes in controlling storm-time geomagnetic variability.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"280 ","pages":"Article 106763"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422310","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}