Advances in Space Research最新文献

{"title":"Flagged data of the Langmuir probes onboard Swarm satellites related extremely low plasma density environment","authors":"Yuhao Zheng,&nbsp;Chao Xiong,&nbsp;Gaofang Mi,&nbsp;Yuanqiang Zhao,&nbsp;Ziyuan Zhu,&nbsp;Artem Smirnov,&nbsp;Rui Yan","doi":"10.1016/j.asr.2025.10.114","DOIUrl":"10.1016/j.asr.2025.10.114","url":null,"abstract":"<div><div>As a widely used instrument for in situ electron density and temperature measurements, the spaceborne Langmuir Probe (LP) provides critical insights into ionospheric structure and dynamics. In this study, we investigate a specific type of anomalous disturbance in the plasma density data recorded by the LP onboard Swarm satellites. In the official Swarm data product, these anomalous disturbances have been flagged as invalid data. Comprehensive analysis shows that these flagged disturbances predominantly occur in regions of extremely low background electron density, such as inside the post-sunset equatorial plasma bubbles (EPBs) and low-density regions at high latitudes. Their occurrence rates are notably higher during nighttime, local winter, and periods of low solar activity, but show no clear dependence on geomagnetic activity. In addition to space environment factors, differences in satellite platforms and payload configurations also contribute to statistical discrepancies in such disturbances. The average background electron densities during these events for Swarm A, B, and C are 440 cm⁻³, 449 cm⁻³, and 692 cm⁻³, respectively. These differences in background levels are likely related to subtle inter-satellite variations in the LP onboard Swarm A, B, and C. Furthermore, there is a clear hemispheric asymmetry in the occurrence of these disturbance events, with many more detected in the Southern Hemisphere than in the Northern Hemisphere. This result indicates that much deeper and more frequent low electron density appear in the southern high-latitude regions, which might be associated with the southern mid-latitude trough. These findings highlight how both space environment and satellite hardware can influence the interpretation of ionospheric measurements.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 400-413"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148528298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the latitudinal variations of AO, SAO, and ISOs in the MLT temperatures","authors":"Kiran,&nbsp;Ravindra P. Singh","doi":"10.1016/j.asr.2025.10.003","DOIUrl":"10.1016/j.asr.2025.10.003","url":null,"abstract":"<div><div>Analysis of two years of OH(3-1) rotational temperatures derived from the PRL Airglow InfraRed Spectrograph (PAIRS) at Ahmedabad (23°N, 72.6°E) reveals a clear presence of annual (AO) and semi-annual (SAO) oscillations, along with intraseasonal oscillations (ISOs) near an altitude of 87 km. Similar oscillations are also observed in SABER-derived temperatures centered over Ahmedabad. However, the NRLMSIS model captures only AO and SAO, failing to reproduce the observed ISOs. Notably, the 75-day oscillation is absent in both PAIRS and SABER temperatures over Ahmedabad, which motivated a broader investigation into the latitudinal distribution of these oscillations. A comprehensive analysis was carried out using longitudinally averaged SABER temperature data, organized at 10° latitude intervals from 80°N to 80°S. Lomb-Scargle spectral analysis was employed to extract the amplitudes of significant oscillations at each latitude band. The results show that the AO and SAO are present across all latitudes, with their amplitudes peaking at the poles and reaching a minimum near the equator, while SAO amplitudes show a secondary peak near the equator. ISOs exhibit strong latitude-dependent variations: the terannual oscillation (TAO) is prominent at low to mid-latitudes, the quarter-annual oscillation (QAO) appears at all latitudes with stronger amplitudes at high latitudes, the 75-day oscillation is confined to mid and high latitudes, and the 60-day oscillation is primarily observed at equatorial and low latitudes. These findings provide new observational evidence for the latitude-dependent amplitude variations of ISOs and quantify their characteristics using PAIRS and SABER temperature measurements in the MLT region.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 83-93"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148528691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal variations of mesoscale perturbations of OH and O2 rotational temperature in Rikubetsu, Shigaraki and Sata","authors":"N.M. Gavrilov,&nbsp;A.V. Koval,&nbsp;A.A. Popov,&nbsp;K. Shiokawa","doi":"10.1016/j.asr.2025.06.023","DOIUrl":"10.1016/j.asr.2025.06.023","url":null,"abstract":"<div><div>The method of digital difference filters has been applied to the analysis of OH and O₂ rotational temperature obtained with airglow temperature photometers installed at Rikubetsu (43.5°N, 143.8°E), Shigaraki (34.8°N, 136.1°E), and Sata (31.0°N, 130.7°E) in Japan. These nightglow observations cover the time interval of 2010–2018 at altitudes between 85 and 90 km. Seasonal variations in the monthly standard deviation of rotational temperature perturbations with periods of 0.7–8 h, which may be partly associated with internal gravity waves (IGWs) in the mesopause region, have been studied. Near the mesopause, seasonal variations in the relative standard deviation of the rotational temperature have maxima, the strength and timing of which depend on the location of the observing site and on the type of nighttime emission. These differences can be caused by differences in the activity of wave sources and conditions of wave propagation, differences in heights of different emission layers and seasonal changes in the complex system of photochemical processes for OH and O₂ nightglows.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 94-102"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148502007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 study of the ionospheric response during intense geomagnetic storms over the Indian low-latitude region during the period 2017–2023","authors":"Prajakta Chougule,&nbsp;Dadaso Shetti,&nbsp;K. Venkatesh,&nbsp;Gopi K. Seemala,&nbsp;Susmita Chougule","doi":"10.1016/j.asr.2025.09.088","DOIUrl":"10.1016/j.asr.2025.09.088","url":null,"abstract":"<div><div>This study investigates the low-latitude ionospheric response to five intense geomagnetic storms using Total Electron Content (TEC), Rate of VTEC Index (ROTI), and S4 index observations from a NavIC receiver observations at an Indian low-latitude station Sangli (Latitude 16.5°N, Longitude 74.3°E). We analyze variations in the Interplanetary Magnetic Field (IMFBz), solar wind parameters (Vsw, Nsw), geomagnetic indices (SYM-H, Dst), and Equatorial Electrojet (EEJ), along with O/N₂ data from the Global Ultraviolet Imager (GUVI). Among the selected storms, September 2017 and August 2018 exhibited positive ionospheric storm effects, while April 2023 showed strong negative effects. The February and March 2023 storms demonstrated both positive and negative responses. VTEC variations during the main and recovery phases were influenced by eastward (positive storm) and westward (negative storm) EEJ, along with thermospheric O/N₂ changes. CME-driven storms caused abrupt VTEC enhancements, whereas CIR-HSS-driven storms led to prolonged disturbances due to sustained southward IMFBz. Daytime VTEC enhancements in September 2017, August 2018, February, and March 2023 were linked to eastward electric fields or increased O/N₂ ratios, while nighttime VTEC depletions in February, March, and April storms resulted from prolonged equatorial electric field suppression. Strong ionospheric irregularities and plasma bubble occurrences were observed, particularly during the 2023 storms with higher ROTI and S4 index values. The extreme EEJ suppression in April 2023 and pre-storm irregularities suggest ionospheric preconditioning.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 154-176"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148502397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of the ionospheric disturbances prior to large earthquakes in Türkiye using Random Forests algorithm","authors":"Nazlican Gengec Zorkun,&nbsp;Makbule Hilal Mutevelli Oncul,&nbsp;Secil Karatay,&nbsp;Faruk Erken,&nbsp;Cafer Budak","doi":"10.1016/j.asr.2025.06.080","DOIUrl":"10.1016/j.asr.2025.06.080","url":null,"abstract":"<div><div>This study investigates the potential of Machine Learning techniques to detect ionospheric precursors of major earthquakes using Total Electron Content (TEC) data. A Random Forest classification algorithm is implemented to IONOLAB-TEC estimates from four significant earthquakes in Türkiye between 2020 and 2023, with magnitudes ranging from Mw 6.7 to 7.8. The algorithm distinguishes between four classes: geomagnetically quiet days, geomagnetically disturbed days, three days preceding earthquakes and earthquake days. Nine statistical features are extracted from TEC data to characterize temporal and spatial ionospheric variations. Results demonstrate that the classifier effectively differentiates between seismo-ionospheric anomalies and other ionospheric disturbances with Macro-Average Accuracy ranging from 93.36 % to 97.76 %. A clear correlation between earthquake magnitude and classification performance is observed with higher magnitude events (Mw 7.8 and 7.5) yielding substantially better classification metrics than lower magnitude events (Mw 6.7). 5-Fold Cross-Validation further confirms this pattern with mean Accuracy increasing progressively from 86.72 % for the lowest magnitude earthquake to 95.56 % for the highest. While the model successfully identifies pre-earthquake ionospheric variations with high Precision and Recall values, occasional misclassification between geomagnetic disturbances and pre-earthquake anomalies highlights the ongoing challenge of distinguishing seismic precursors from space weather effects. These findings demonstrate the potential of Machine Learning approaches for detecting earthquake precursors in ionospheric data and suggest possibilities for developing early warning systems through ionospheric monitoring.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 263-278"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148528743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics of slant sporadic-E layers observed at low-latitudes","authors":"Peter T. Muka,&nbsp;Marcio T.A.H. Muella,&nbsp;Fredson Conceição-Santos,&nbsp;Laysa C.A. Resende,&nbsp;Paulo R. Fagundes,&nbsp;Olufemi L. Ogunmola,&nbsp;Pedro A. Fontes,&nbsp;Valdir G. Pillat,&nbsp;Mariah Cesar,&nbsp;Rodolfo de Jesus","doi":"10.1016/j.asr.2025.09.090","DOIUrl":"10.1016/j.asr.2025.09.090","url":null,"abstract":"<div><div>This study investigates the occurrence, characteristics, and formation mechanisms of slant sporadic-E layers (Es_s). The Es_s-type layers observed at the Brazilian low-latitude stations of Jataí (17.9°S, 51.7°W) and São José dos Campos (23.2°S, 45.8°W), are analyzed using ionosonde data recorded for four months (April, June, September, and December) of 2016. Parameters such as top frequency (<em>ftEs</em>), blanketing frequency (<em>fbEs</em>), and virtual height (<em>h’Es</em>) were scaled from ionograms to characterize the slant (Es_s) traces. The results show that Es_s-type layers predominantly occur at night, forming between 95 and 120 km altitudes, with monthly and local variations. Model simulations using meteor radar-derived winds revealed that strong and stable zonal wind shear are associated with increased Es_s-type layer activity. In addition, wavelet spectral analyses of <em>ftEs</em> and <em>fbEs</em> showed that tidal periodicities (diurnal, semidiurnal, terdiurnal, and quarterdiurnal) and their interactions with gravity waves seem to play fundamental roles in the formation of Es_s-type layers. A comparison of ΔF (<em>ftEs-fbEs</em>) during Es_s-type events confirmed the presence of strong plasma density gradients, supporting the hypothesis that the slanted traces in ionograms result mostly from oblique reflections in inhomogeneous Es layer structures. However, the appearance of slant Es traces may in some cases be related to an actual tilt of the layer. Other relevant aspects of the observations associated with the possible physical mechanisms behind the formation of Es_s-type layers at low latitudes are highlighted and discussed.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 66-82"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148528690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Planar trend model for the midlatitude ionosphere","authors":"Solen Kumbay Yildiz,&nbsp;Orhan Arikan,&nbsp;Feza Arikan","doi":"10.1016/j.asr.2025.04.001","DOIUrl":"10.1016/j.asr.2025.04.001","url":null,"abstract":"<div><div>Midlatitude Ionosphere, which is a passage region between polar and equatorial ionospheres, poses its own peculiarities. Total Electron Content (TEC) is one of the main parameters of the Ionosphere, corresponding to the total number of electrons on a ray path. TEC can be considered as the projection of electron density incorporating the inherent spatiotemporal variabilities of the Ionosphere occurring at various scales. In this study, we have demonstrated that midlatitude TEC can be represented as a planar model whose coefficients can be estimated in closed form in the Least Squares sense using Global Ionospheric Maps (GIM). For 24 regions in the Northern Hemisphere, and their 24 geographic conjugates with respect to the geomagnetic equator in the Southern Hemisphere, the three model coefficients are estimated from January 1, 2000, 00:00 UT to December 31, 2022, 22:00 UT covering about two solar cycles with 2 h temporal resolution. The regions of 10 degrees of latitude and 20 degrees of longitude are arranged around a center coordinate chosen to correspond to a GIM grid point and a time frame in Universal Time (UT). The validity and accuracy of the model coefficients are tested using Square of the Normalized Metric Distance (SNMD) and Symmetric Kullback-Leibler Distance (SKLD). We have also computed the coefficient of determination between the SNMD and SKLD revealing a fit of 99.995 % to the planar model, where deviations from the planar model occur only on severe geomagnetic disturbance days and hours. 77 % of the regions indicate a very strong fit with coefficients of determination higher than 0.95. The remaining 23 % of the regions which are either on or neighboring the geomagnetic field anomalies, the coefficient of determination values are higher than 0.88, indicating a good fit to the planar model. Unlike previous region-specific models proposed in the literature with high computational complexity and problems in duplicability, the whole midlatitude region is covered in our model directly through region, date and time specific coefficients. For all 48 regions and 23 years, the coefficients are made available to the public in a user-friendly fashion and they can be downloaded from <span><span>https://www.ee.hacettepe.edu.tr/∼solen/_PlanarTrendModel</span><svg><path></path></svg></span>. These coefficients can be used in further interpolation, prediction and tracking routines to reveal the underlying random field structure of midlatitude ionosphere.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 316-330"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148528745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abnormal response of ionospheric irregularities in the eastern Pacific region during a great magnetic storm in April 2023","authors":"Sheping Shang,&nbsp;Jiankui Shi,&nbsp;Maosheng He,&nbsp;Zhengwei Cheng,&nbsp;Guojun Wang,&nbsp;Zheng Wang","doi":"10.1016/j.asr.2026.02.029","DOIUrl":"10.1016/j.asr.2026.02.029","url":null,"abstract":"<div><div>Using the multiple ground-based/space-based observations, an abnormal response of ionospheric irregularities in the eastern Pacific region during the recovery phase of the great magnetic storm on 24 April 2023 was analyzed. The ground-based GPS observations exhibited ionospheric irregularities occurred from night to day, lasting for over ten hours, with the longest exceeding 14 h, especially near the magnetic equatorial region. SWARM satellites detected significant plasma bubble/disturbance structures near sunset and in the morning when crossing the low latitude and equatorial region from the western Americas to the eastern Pacific. The satellites (C2E1-C2E5) of COSMIC-2 detected the strong ionospheric bubbles and their quasi periodic structures when crossing the low latitude region from the eastern Pacific to the western Americas (−180° to −60°), which occurred from sunset to daytime, lasting up to 10–14 h. The enhanced eastward electric field and the seed disturbance may be main factors for the occurrence of ionospheric irregularities in the eastern Pacific region during the recovery phase of magnetic storm on 24th.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"78 1","pages":"Pages 114-129"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148502395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ENSO-influenced Mekong plume extension revealed by causality between estuarine water level and GRACE-derived oceanic height","authors":"Hok Sum Fok ,&nbsp;Zhongtian Ma","doi":"10.1016/j.asr.2026.01.020","DOIUrl":"10.1016/j.asr.2026.01.020","url":null,"abstract":"<div><div>Understanding river plume extension is essential for resolving freshwater connectivity and biogeochemical fluxes in the open ocean. However, it remains poorly understood due to the limited detectable transport ranges of isotope measurements, numerical models, and satellite methods. Rather than cross-correlating runoff with <em>GRACE</em>-derived oceanic equivalent water height (OEWH) as in previous studies, this study cross-correlates estuarine water level—served as a runoff proxy—with <em>GRACE</em>-derived OEWH/Ocean bottom pressure. Granger and Liang causality tests are further applied to examine whether estuarine output potentially drives the <em>GRACE</em>-derived oceanic height changes, thereby validating the inferred spatiotemporal extent of far-field plume transport across the Sunda Shelf Sea (SSS) and South China Sea (SCS). Isolating interannual variability via multi-wavelet analyses, we found that while La Niña tends to enhance offshore extension across SSS and SCS, alternating El Niño-La Niña phases stagnate transport in central SSS. Comparison with isotope-estimated plume ages confirms the method’s potential applicability. Notably, the inferred Mekong plume might extend to ∼18°N in SCS that represents an exceptionally long range of the plume transport. These findings provide a potential alternative for determining extended plume transport duration patterns and highlight the role of climate variability in reshaping estuary-to-shelf transport.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 6","pages":"Pages 6675-6691"},"PeriodicalIF":2.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ionospheric disturbances as precursor signals of the March 28, 2025, Myanmar earthquake","authors":"C. Pansong ,&nbsp;S. Ruttanaburee ,&nbsp;P. Pornsopin ,&nbsp;P. Kenpankho","doi":"10.1016/j.asr.2026.01.070","DOIUrl":"10.1016/j.asr.2026.01.070","url":null,"abstract":"<div><div>This study examined the ionospheric response associated with the Mw 7.7 Myanmar earthquake on March 28, 2025, using GPS-derived Total Electron Content (TEC) data from seven GNSS stations across Thailand. TEC variations were analyzed alongside Dst and Kp indices, as well as ionosonde-derived parameters, namely the critical frequency of the F2 layer (<em>foF</em>2), the peak height of the F2 layer (<em>hmF</em>2), the disturbances in <em>N</em>m<em>F</em>2, and the slab thickness (τ), which were obtained from three IGS-supported stations. We detected abnormal variations in TEC approximately 15 days before the earthquake (13–27 March 2025), characterized by alternating positive and negative deviations. The TEC exhibited alternating positive and negative deviations throughout the analysis period, reflecting ionospheric variability prior to the earthquake. During the early period (13–18 March), the deviations remained within approximately ±6 TECU. However, from 19 to 21 and 23–24 March, moderate fluctuations were observed, particularly at mid- and low-latitude stations (UTHG, THBK, THCP, and THPK), where ΔTEC ranged from ±6 to 10 TECU. The TEC decrease occurred on 25 March under weak geomagnetic conditions (Dst &gt;  −30 nT) at the northern stations MAEH (−18.40 TECU), THCM (−15.65 TECU), and NANN (−15.73 TECU), marking the most pronounced negative anomaly observed during the study period. Subsequently, on 26–27 March, TEC values recovered to positive anomalies of +4 to +10 TECU, indicating a return to normal ionospheric conditions. To objectively identify pre-seismic ionospheric anomalies, a Median Absolute Deviation (MAD) approach was applied using a ±1.34MAD threshold. This statistical technique effectively detects subtle deviations while minimizing transient noise. The results reveal coherent TEC depletions across multiple stations on 25 March, suggesting the presence of localized ionospheric disturbances potentially related to seismo-ionospheric processes rather than geomagnetic effects. Furthermore, concurrent anomalous increases in <em>foF</em>2 and <em>hmF</em>2, along with a reduction in slab thickness near the epicentral region, indicate vertical uplift of the F2 layer, consistent with possible Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) mechanisms.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 6","pages":"Pages 7002-7021"},"PeriodicalIF":2.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}