Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.027
Amiya Gayen , Sk. Mafizul Haque
Soil erosion is considered a key concern in achieving the United Nations Sustainable Development Goals (SDGs), as water erosion threatens both environmental quality and human well-being. This study aims to quantify soil erosion vulnerability and socio-economic conditions of local people in the Pathro River Basin, located in a tropical humid region of Jharkhand and Bihar, India. The specific objectives are to (i) assess spatial patterns of soil erosion vulnerability, (ii) analyse their relationship with local socio-economic conditions, and (iii) propose some suitable management strategies. Twenty-eight erosion vulnerability determining factors, categories into exposure, sensitivity, and adaptive capacity, were integrated using a hybrid modeling framework combining machine learning and deep learning algorithms. Four models (i.e., Random Forest (RF), Bagging, Deep Learning Neural Network (DLNN), and Artificial Neural Network (ANN) were applied to generate the Soil Erosion Vulnerability (SEV) index ranging from 0.0 to 1.0. The vulnerability maps classified the study area into five classes, with high and very high soil erosion vulnerability zones accounting for 25 % occupancy within the river basin, often coinciding with socio-economically disadvantaged areas. Model evaluation using true positive rate, false positive rate, area under the receiver operating characteristic curve, Mean Absolute Error (MAE), and Root Mean Square Error (RMSE) reflected that DLNN delivered the highest prediction capacity. This effort would be helpful for the robust policy intervention to minimize erosion vulnerability and enhance environmental resilience with the conservation of soil resources.
{"title":"Methodological augmentation for assessing soil erosion vulnerability through the integration of DL and MLA in a tropical river basin","authors":"Amiya Gayen , Sk. Mafizul Haque","doi":"10.1016/j.asr.2025.11.027","DOIUrl":"10.1016/j.asr.2025.11.027","url":null,"abstract":"<div><div>Soil erosion is considered a key concern in achieving the United Nations Sustainable Development Goals (SDGs), as water erosion threatens both environmental quality and human well-being. This study aims to quantify soil erosion vulnerability and socio-economic conditions of local people in the Pathro River Basin, located in a tropical humid region of Jharkhand and Bihar, India. The specific objectives are to (i) assess spatial patterns of soil erosion vulnerability, (ii) analyse their relationship with local socio-economic conditions, and (iii) propose some suitable management strategies. Twenty-eight erosion vulnerability determining factors, categories into exposure, sensitivity, and adaptive capacity, were integrated using a hybrid modeling framework combining machine learning and deep learning algorithms. Four models (i.e., Random Forest (RF), Bagging, Deep Learning Neural Network (DLNN), and Artificial Neural Network (ANN) were applied to generate the Soil Erosion Vulnerability (SEV) index ranging from 0.0 to 1.0. The vulnerability maps classified the study area into five classes, with high and very high soil erosion vulnerability zones accounting for 25 % occupancy within the river basin, often coinciding with socio-economically disadvantaged areas. Model evaluation using true positive rate, false positive rate, area under the receiver operating characteristic curve, Mean Absolute Error (MAE), and Root Mean Square Error (RMSE) reflected that DLNN delivered the highest prediction capacity. This effort would be helpful for the robust policy intervention to minimize erosion vulnerability and enhance environmental resilience with the conservation of soil resources.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 2956-2978"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081799","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.047
Yunpeng Bai, Huizhong Zhu, Chunhua Jiang
<div><div>Zenith Tropospheric Delay (ZTD) and Precipitable Water Vapor (PWV) are key parameters in climate change research and numerical weather prediction (NWP), and their high-precision real-time acquisition is crucial for meteorological applications. This study systematically evaluates the product accuracy and real-time ZTD/PWV retrieval performance of the current mainstream satellite-based precise point positioning (PPP) services—BDS-3 PPP-B2b, Galileo HAS, and QZSS MADOCA-PPP—using observation data from Multi-GNSS Experiment (MGEX) stations. Using the tropospheric products released by IGS centers, radiosonde data, and ERA5 reanalysis as reference baselines, this study—through analyses of spatiotemporal consistency as well as assessments of seasonal and regional variability—reveals the performance characteristics of each service under different geographical and climatic conditions. The results indicate that there is no systematic bias between the ZTD estimates from all services and the IGS reference values, with the WUM post-processed product demonstrating the highest overall accuracy. Among the real-time products, MADOCA-ZTD and CNES-ZTD show the highest accuracy, with mean STD of 9.03 mm and 11.81 mm, respectively. The accuracy of HAS-ZTD is slightly lower than that of MADOCA-ZTD, while B2b-ZTD achieves relatively high precision at several stations within China, approaching the level of post-processed products. However, due to its limited service coverage, its overall accuracy remains the lowest among the evaluated real-time services. Meanwhile, the WUM post-processed product continues to demonstrate the highest accuracy in PWV retrieval, with annual mean STDs of 1.71 mm and 2.36 mm under the two reference baselines, and bias values maintained within ±0.30 mm. Among the real-time services, MADOCA-PPP exhibits the best overall performance, with annual mean STDs of 2.01 mm and 2.77 mm under the two reference baselines, and bias values confined within ±0.50 mm. The correlation coefficient reaches approximately 0.95, and the service maintains high stability even under complex and rapidly changing water vapor conditions. The HAS service performs stably within the European core service area; however, its accuracy decreases significantly when extended into non-nominal regions, with noticeable negative biases observed in summer. This reflects the issue of uneven service coverage. B2b-PWV exhibits significant regional dependence: stations located within China show high precision, with STD values below 2 mm, whereas accuracy declines markedly in regions farther from China. The performance is strongly influenced by factors such as station latitude, observation quality, and the accuracy of orbit and clock products. Overall, all real-time services achieve their highest accuracy in winter and the largest errors in summer, exhibiting a clear seasonal dependence and a pronounced influence from geographical location. The study shows that current satellite-b
{"title":"Real-time atmospheric precipitable water retrieval performance evaluation based on satellite-based precise point positioning","authors":"Yunpeng Bai, Huizhong Zhu, Chunhua Jiang","doi":"10.1016/j.asr.2025.11.047","DOIUrl":"10.1016/j.asr.2025.11.047","url":null,"abstract":"<div><div>Zenith Tropospheric Delay (ZTD) and Precipitable Water Vapor (PWV) are key parameters in climate change research and numerical weather prediction (NWP), and their high-precision real-time acquisition is crucial for meteorological applications. This study systematically evaluates the product accuracy and real-time ZTD/PWV retrieval performance of the current mainstream satellite-based precise point positioning (PPP) services—BDS-3 PPP-B2b, Galileo HAS, and QZSS MADOCA-PPP—using observation data from Multi-GNSS Experiment (MGEX) stations. Using the tropospheric products released by IGS centers, radiosonde data, and ERA5 reanalysis as reference baselines, this study—through analyses of spatiotemporal consistency as well as assessments of seasonal and regional variability—reveals the performance characteristics of each service under different geographical and climatic conditions. The results indicate that there is no systematic bias between the ZTD estimates from all services and the IGS reference values, with the WUM post-processed product demonstrating the highest overall accuracy. Among the real-time products, MADOCA-ZTD and CNES-ZTD show the highest accuracy, with mean STD of 9.03 mm and 11.81 mm, respectively. The accuracy of HAS-ZTD is slightly lower than that of MADOCA-ZTD, while B2b-ZTD achieves relatively high precision at several stations within China, approaching the level of post-processed products. However, due to its limited service coverage, its overall accuracy remains the lowest among the evaluated real-time services. Meanwhile, the WUM post-processed product continues to demonstrate the highest accuracy in PWV retrieval, with annual mean STDs of 1.71 mm and 2.36 mm under the two reference baselines, and bias values maintained within ±0.30 mm. Among the real-time services, MADOCA-PPP exhibits the best overall performance, with annual mean STDs of 2.01 mm and 2.77 mm under the two reference baselines, and bias values confined within ±0.50 mm. The correlation coefficient reaches approximately 0.95, and the service maintains high stability even under complex and rapidly changing water vapor conditions. The HAS service performs stably within the European core service area; however, its accuracy decreases significantly when extended into non-nominal regions, with noticeable negative biases observed in summer. This reflects the issue of uneven service coverage. B2b-PWV exhibits significant regional dependence: stations located within China show high precision, with STD values below 2 mm, whereas accuracy declines markedly in regions farther from China. The performance is strongly influenced by factors such as station latitude, observation quality, and the accuracy of orbit and clock products. Overall, all real-time services achieve their highest accuracy in winter and the largest errors in summer, exhibiting a clear seasonal dependence and a pronounced influence from geographical location. The study shows that current satellite-b","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3039-3060"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081811","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.040
Saisai Gao , Ran Li , Jiatong Wu , Xiaoyun Wan , Rui Guo , Xiaojie Li , Shanshi Zhou , Guang Yang
Signal distortion bias (SDB) has already impacted the accuracy of various GNSS precise products computed using hybrid receiver. Signal distortion bias is influenced by factors such as receiver front-end filter bandwidth, code correlator spacing, and multipath mitigation algorithms, causing different receiver types to distort the same navigation signal to varying degrees. With the construction and enhancement of the BeiDou Global Navigation Satellite System (BDS-3) and its augmentation systems, an increasing number of reference stations will be deployed worldwide, accompanied by a substantially more diverse range of receiver types, resulting in an enormous volume of SDB correction values. To better process the globally massive SDB values, we propose an adaptive clustering method tailored for SDB processing and construct an SDB model based on the clustering results. The necessity of clustering was validated by analyzing standard single point positioning (SPP) results when incorporating SDB model values from both majority and minority station categories. The results indicate that: 1) Significant differences characteristics exist in SDB among receivers of the same manufacturer or even receivers of the same type. 2) The improved adaptive clustering algorithm can efficiently and accurately differentiate signal distortion biases, and applying the resulting SDB model effectively enhances SPP accuracy and reduces precise point positioning (PPP) convergence time. 3) Applying SDB values from majority receiver types to correct SPP at minority type stations leads to a 3.8 % reduction in positioning accuracy, and clustering enables fine differentiation of receiver types to effectively mitigate this issue.
{"title":"Design of BDS-3 signal distortion bias model and analysis of its performance","authors":"Saisai Gao , Ran Li , Jiatong Wu , Xiaoyun Wan , Rui Guo , Xiaojie Li , Shanshi Zhou , Guang Yang","doi":"10.1016/j.asr.2025.11.040","DOIUrl":"10.1016/j.asr.2025.11.040","url":null,"abstract":"<div><div>Signal distortion bias (SDB) has already impacted the accuracy of various GNSS precise products computed using hybrid receiver. Signal distortion bias is influenced by factors such as receiver front-end filter bandwidth, code correlator spacing, and multipath mitigation algorithms, causing different receiver types to distort the same navigation signal to varying degrees. With the construction and enhancement of the BeiDou Global Navigation Satellite System (BDS-3) and its augmentation systems, an increasing number of reference stations will be deployed worldwide, accompanied by a substantially more diverse range of receiver types, resulting in an enormous volume of SDB correction values. To better process the globally massive SDB values, we propose an adaptive clustering method tailored for SDB processing and construct an SDB model based on the clustering results. The necessity of clustering was validated by analyzing standard single point positioning (SPP) results when incorporating SDB model values from both majority and minority station categories. The results indicate that: 1) Significant differences characteristics exist in SDB among receivers of the same manufacturer or even receivers of the same type. 2) The improved adaptive clustering algorithm can efficiently and accurately differentiate signal distortion biases, and applying the resulting SDB model effectively enhances SPP accuracy and reduces precise point positioning (PPP) convergence time. 3) Applying SDB values from majority receiver types to correct SPP at minority type stations leads to a 3.8 % reduction in positioning accuracy, and clustering enables fine differentiation of receiver types to effectively mitigate this issue.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3022-3038"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081925","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.055
Zixuan Ge , Yongkai Wang , Wenhao Wu , Jie Liu , Weijie Ran , Peixian Yuan , Yanan Su , Jiangtao Xu , Jiyuan Hu , Peijie Zhu , Yu Zhang
The South-to-North Water Diversion Project (SNWDP) is a strategic national project in China. In recent years, uneven surface deformation has occurred frequently along the project route, potentially causing leakage, fractures, and other hazards that threaten operational safety. The high-precision routine deformation monitoring is crucial to ensure the stable operation of this significant hydraulic infrastructure. Interferometric synthetic aperture radar (InSAR) can capture subtle ground deformations over extensive areas. However, conventional image datasets often suffer from limitations such as low spatial and temporal resolution or high costs. In this study, Chinese small SAR satellites, including “Fucheng-1” and “Shenqi” series, were employed to monitor large-scale water diversion projects for the first time. Distributed scatterer InSAR (DS-InSAR) technology under multi-source SAR imagery was utilized to monitor the Tianjin section of the SNWDP, supplemented with corner reflector (CR) for analyzing deformation results in low-coherence agricultural areas along the route. The monitoring results indicate a high spatial consistency between the results derived from Sentinel-1A and the “Fucheng-1” and “Shenqi” satellites. The average coherence coefficients of the dual-star constellation show an improvement compared to Sentinel-1A with a similar temporal baseline. Among the selected monitoring points, the minimum Maximum Absolute Error (MaxAE) value is 1.699 mm/yr, and the highest Pearson correlation coefficient (PCC) reaches 0.977, which indicates stable orbit control capabilities, dual-star constellation interferometry capabilities, and time-series resolution capabilities of Chinese small SAR satellites. The results indicate significant regional ground subsidence happened in Xiong County and Gu’an area of Langfang, Hebei Province, although a recent trend of subsidence mitigation has emerged.
{"title":"Preliminary application of Chinese high-resolution small SAR satellites in large-scale monitoring of the middle route of the South-to-North Water Diversion Project","authors":"Zixuan Ge , Yongkai Wang , Wenhao Wu , Jie Liu , Weijie Ran , Peixian Yuan , Yanan Su , Jiangtao Xu , Jiyuan Hu , Peijie Zhu , Yu Zhang","doi":"10.1016/j.asr.2025.11.055","DOIUrl":"10.1016/j.asr.2025.11.055","url":null,"abstract":"<div><div>The South-to-North Water Diversion Project (SNWDP) is a strategic national project in China. In recent years, uneven surface deformation has occurred frequently along the project route, potentially causing leakage, fractures, and other hazards that threaten operational safety. The high-precision routine deformation monitoring is crucial to ensure the stable operation of this significant hydraulic infrastructure. Interferometric synthetic aperture radar (InSAR) can capture subtle ground deformations over extensive areas. However, conventional image datasets often suffer from limitations such as low spatial and temporal resolution or high costs. In this study, Chinese small SAR satellites, including “Fucheng-1” and “Shenqi” series, were employed to monitor large-scale water diversion projects for the first time. Distributed scatterer InSAR (DS-InSAR) technology under multi-source SAR imagery was utilized to monitor the Tianjin section of the SNWDP, supplemented with corner reflector (CR) for analyzing deformation results in low-coherence agricultural areas along the route. The monitoring results indicate a high spatial consistency between the results derived from Sentinel-1A and the “Fucheng-1” and “Shenqi” satellites. The average coherence coefficients of the dual-star constellation show an improvement compared to Sentinel-1A with a similar temporal baseline. Among the selected monitoring points, the minimum Maximum Absolute Error (MaxAE) value is 1.699 mm/yr, and the highest Pearson correlation coefficient (PCC) reaches 0.977, which indicates stable orbit control capabilities, dual-star constellation interferometry capabilities, and time-series resolution capabilities of Chinese small SAR satellites. The results indicate significant regional ground subsidence happened in Xiong County and Gu’an area of Langfang, Hebei Province, although a recent trend of subsidence mitigation has emerged.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3119-3140"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081881","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.063
Wenqian Zhou , Jianhui Cui , Rui Tu , Rufei Liu , Zeyu Li , Xuan Han
Integrated navigation software with global navigation satellite system (GNSS) and inertial navigation system (INS) has been widely applied in vehicular navigation. However, the positioning accuracy of different software solutions varies due to differences in algorithms, environmental conditions and devices. To evaluate the positioning performance of different integrated navigation software in various urban environments, this study conducts real-world vehicle experiments and provides a detailed analysis of the positioning accuracy of five software KF-GINS, OB-GINS, IGNAV, GINav and PSINS. The algorithms and reasonable usage strategies of all above five software are given as well. For manned vehicle scenarios, the positioning accuracy of each software can reach the centimeter-level on open road and the decimeter-level on tree occlusion road, while the position errors diverge in tunnel. The attitude accuracy remains within 3°. Positioning accuracy is improved under multi-GNSS mode compared to GPS-only mode. IGNAV achieves the highest accuracy in most scenarios by expanding the dimensions of the extended Kalman filter state and observation equations. KF-GINS assigns higher weights to GNSS positioning results, leading to better accuracy than IGNAV on open road. GINav exhibits relatively large initial state errors which affect the accuracy of subsequent positioning. PSINS achieves a favorable balance between speed and reliability, providing reasonably accurate solutions in a short computation time. OB-GINS utilizes factor graph optimization to make full use of redundant observations, resulting in stronger robustness and more stable accuracy. Except under extremely harsh conditions, all software can provide relatively reliable positioning results. For low-speed unmanned ground vehicle scenarios, the positioning accuracy of various software can also be maintained at the meter level, but they exhibit poor adaptability in attitude determination, failing to output reliable orientation estimates. For computational efficiency of the various software, PSINS achieves the fastest computation speed.
{"title":"Vehicle-borne GNSS/INS integration performance in urban environments with KF-GINS, IGNAV, GINav, PSINS and OB-GINS","authors":"Wenqian Zhou , Jianhui Cui , Rui Tu , Rufei Liu , Zeyu Li , Xuan Han","doi":"10.1016/j.asr.2025.11.063","DOIUrl":"10.1016/j.asr.2025.11.063","url":null,"abstract":"<div><div>Integrated navigation software with global navigation satellite system (GNSS) and inertial navigation system (INS) has been widely applied in vehicular navigation. However, the positioning accuracy of different software solutions varies due to differences in algorithms, environmental conditions and devices. To evaluate the positioning performance of different integrated navigation software in various urban environments, this study conducts real-world vehicle experiments and provides a detailed analysis of the positioning accuracy of five software KF-GINS, OB-GINS, IGNAV, GINav and PSINS. The algorithms and reasonable usage strategies of all above five software are given as well. For manned vehicle scenarios, the positioning accuracy of each software can reach the centimeter-level on open road and the decimeter-level on tree occlusion road, while the position errors diverge in tunnel. The attitude accuracy remains within 3°. Positioning accuracy is improved under multi-GNSS mode compared to GPS-only mode. IGNAV achieves the highest accuracy in most scenarios by expanding the dimensions of the extended Kalman filter state and observation equations. KF-GINS assigns higher weights to GNSS positioning results, leading to better accuracy than IGNAV on open road. GINav exhibits relatively large initial state errors which affect the accuracy of subsequent positioning. PSINS achieves a favorable balance between speed and reliability, providing reasonably accurate solutions in a short computation time. OB-GINS utilizes factor graph optimization to make full use of redundant observations, resulting in stronger robustness and more stable accuracy. Except under extremely harsh conditions, all software can provide relatively reliable positioning results. For low-speed unmanned ground vehicle scenarios, the positioning accuracy of various software can also be maintained at the meter level, but they exhibit poor adaptability in attitude determination, failing to output reliable orientation estimates. For computational efficiency of the various software, PSINS achieves the fastest computation speed.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3166-3189"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081882","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.091
Rituraj Neog , Behnam Ghasemzadeh
Urban sprawl is a critical environmental issue worldwide, specifically in growing urban regions like Dimapur Urban Area (DUA) in Northeast India. The study investigates spatio-temporal dynamics, patterns, and drivers of urban sprawl at DUA over a span of 30 years (1994–2024) using a mixed model of geospatial and statistical approaches. Multi-temporal Landsat images, OSM, and CartoDEM data were incorporated to assess land use dynamics, quantify built-up growth, and evaluate landscape analysis. Urban sprawl was examined using the Gini coefficient, the UEII (urban expansion intensity index), and landscape metrics. The built-up area sprawled almost six-fold from 4.19 sq km in 1994 to 26.81 sq km in 2024, mainly at the cost of arable land and vegetation. The consistently declining Gini coefficient from 0.66 to 0.35 indicates transitions from concentrated to spatially more disperse urban development. UEII detected intense urban sprawl, profoundly in the northeastern, western, and southern zones, mostly between 2014 and 2024. Landscape matrices also established a change from compact to scattered urban growth. The employed geographically weighted regression (GWR) analysis revealed mean slope and urban amenities as significant factors of urban expansion, with their rising role over time (R2 = 41.7 %). The demarcations of residual zones offer a significant insight for urban planners to address unaccounted factors of urban sprawl, efficient land use planning and curtail unregulated development. Thus the study prioritizes the role of geospatial technology and statistical approaches to promote sustainable urban growth in a mid-sized city like Dimapur.
{"title":"Drivers and dynamics of urban sprawl in Dimapur, India (1994–2024): a Gini, UEII, and geographically weighted regression-based assessment","authors":"Rituraj Neog , Behnam Ghasemzadeh","doi":"10.1016/j.asr.2025.11.091","DOIUrl":"10.1016/j.asr.2025.11.091","url":null,"abstract":"<div><div>Urban sprawl is a critical environmental issue worldwide, specifically in growing urban regions like Dimapur Urban Area (DUA) in Northeast India. The study investigates spatio-temporal dynamics, patterns, and drivers of urban sprawl at DUA over a span of 30 years (1994–2024) using a mixed model of geospatial and statistical approaches. Multi-temporal Landsat images, OSM, and CartoDEM data were incorporated to assess land use dynamics, quantify built-up growth, and evaluate landscape analysis. Urban sprawl was examined using the Gini coefficient, the UEII (urban expansion intensity index), and landscape metrics. The built-up area sprawled almost six-fold from 4.19 sq km in 1994 to 26.81 sq km in 2024, mainly at the cost of arable land and vegetation. The consistently declining Gini coefficient from 0.66 to 0.35 indicates transitions from concentrated to spatially more disperse urban development. UEII detected intense urban sprawl, profoundly in the northeastern, western, and southern zones, mostly between 2014 and 2024. Landscape matrices also established a change from compact to scattered urban growth. The employed geographically weighted regression (GWR) analysis revealed mean slope and urban amenities as significant factors of urban expansion, with their rising role over time (R<sup>2</sup> = 41.7 %). The demarcations of residual zones offer a significant insight for urban planners to address unaccounted factors of urban sprawl, efficient land use planning and curtail unregulated development. Thus the study prioritizes the role of geospatial technology and statistical approaches to promote sustainable urban growth in a mid-sized city like Dimapur.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3311-3329"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081345","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.086
Ákos Kereszturi , Ildikó Gyollai , Sándor Biri , Zoltán Juhász , Bernadett D. Pál , Richárd Rácz , Dániel Rezes , Béla Sulik , Máté Szabó , Péter Szávai , Zoltán Szalai
We investigate the effects of space weathering on asteroid surfaces by exposing the NWA 10580 meteorite to 1 keV solar wind proton irradiation, with a total fluence of up to 1017 ions/cm2, equivalent to 10 Myr of exposure in space. We collect pre- and post-irradiation spectra using near-infrared spectroscopy and micro-X-ray diffraction. We observed irradiation-induced amorphization, reflected in systematic shifts in d-spacing and peak broadening of crystalline phases. Orthopyroxene and carbonates showed an increasing d-spacing consistent with previous studies, while olivine exhibited changes associated with magnesium loss. Pyroxene spectra revealed the disappearance of minor absorption bands. In some cases, irregular d-spacing variations suggest metastable effects linked to pre-existing defects. These results improve our understanding of mineralogical evolution under space weathering, support the interpretation of asteroid spectral data in future missions and the development of spectral detectors. Comparing the pristine samples with the ones exposed to the highest irradiation level, the largest peak position shift was observed for the olivine 835 nm band (14 nm), whereas the pyroxene band at 1938 nm showed the smallest variation (1 nm). In terms of FWHM, the pyroxene band at 1938 nm and the OH band exhibited the most pronounced broadening (93 nm and 65 nm), while the olivine bands at 835 nm and 860 nm showed only minor changes (6 nm and 10 nm). These results could be used and applied for the selection of band positions for small, low cost infrared detectors onboard future cubesat missions.
{"title":"Spectral changes of the NWA 10580 meteorite under simulated space weathering: Insights from VIS–NIR and microXRD analyses","authors":"Ákos Kereszturi , Ildikó Gyollai , Sándor Biri , Zoltán Juhász , Bernadett D. Pál , Richárd Rácz , Dániel Rezes , Béla Sulik , Máté Szabó , Péter Szávai , Zoltán Szalai","doi":"10.1016/j.asr.2025.11.086","DOIUrl":"10.1016/j.asr.2025.11.086","url":null,"abstract":"<div><div>We investigate the effects of space weathering on asteroid surfaces by exposing the NWA 10580 meteorite to 1 keV solar wind proton irradiation, with a total fluence of up to 10<sup>17</sup> ions/cm<sup>2</sup>, equivalent to <span><math><mrow><mo>∼</mo></mrow></math></span>10 Myr of exposure in space. We collect pre- and post-irradiation spectra using near-infrared spectroscopy and micro-X-ray diffraction. We observed irradiation-induced amorphization, reflected in systematic shifts in d-spacing and peak broadening of crystalline phases. Orthopyroxene and carbonates showed an increasing d-spacing consistent with previous studies, while olivine exhibited changes associated with magnesium loss. Pyroxene spectra revealed the disappearance of minor absorption bands. In some cases, irregular d-spacing variations suggest metastable effects linked to pre-existing defects. These results improve our understanding of mineralogical evolution under space weathering, support the interpretation of asteroid spectral data in future missions and the development of spectral detectors. Comparing the pristine samples with the ones exposed to the highest irradiation level, the largest peak position shift was observed for the olivine 835 nm band (14 nm), whereas the pyroxene band at 1938 nm showed the smallest variation (1 nm). In terms of FWHM, the pyroxene band at 1938 nm and the OH band exhibited the most pronounced broadening (93 nm and 65 nm), while the olivine bands at 835 nm and 860 nm showed only minor changes (6 nm and 10 nm). These results could be used and applied for the selection of band positions for small, low cost infrared detectors onboard future cubesat missions.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3956-3972"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081522","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.065
Achraf Djerida
Anomaly detection in satellite telemetry is key step toward safe and effective operation in ground and space. However, the task is challenged with the complexity of the alarms, big data size and absence of enough reliable ground-truth datasets. Even though supervised methods can result in superior performance for the available datasets, their generalization can be limited due to the complexity of the telemetry and the limited dataset size and quality. To cope with the complexity, we propose an anomaly detection framework based on frequent pattern mining and clustering. The telemetry data is discretized and transformed into a set of transactions based on their values. Then, clustering is introduced to consider different operating modes that can result in false alarms if one global model is adopted. The FP-Growth algorithm is employed to extract the association rules based on the support, confidence and lift criteria. The selected rules represent the normal operation phases. To cope with the reliability, the proposed method is evaluated in the recent ESA benchmark dataset OPS-SAT with 23 unsupervised methods having different architectures and methodologies. Results show superior performance based on different criteria with the proposed method producing the best F1-score (0.754) and recall (0.788) using only one associated rule. In addition, the implementation of these rules is simple which is key toward the onboard-processing.
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We investigate the occurrence of wave-like fluctuations (WFs) in the nighttime lower ionosphere during solar minimum conditions (2008–2009) using Very Low Frequency (VLF) narrowband signals transmitted from NAA (US Cutler, Maine, f = 24 kHz) and NDK (US LaMoure, North Dakota, f = 25.2 kHz) stations and recorded at two Peruvian stations PLO (Lima) and PIU (Piura). These propagation paths span predominantly low-latitude regions and exhibit similar characteristics, as they are quasi-parallel, enabling reliable comparisons under similar geophysical and geomagnetic conditions. Statistical and wavelet spectral analysis reveal a persistent daily presence of WFs, with dominant periods between 10 and 15 min across all VLF propagation paths. The second most frequent WFs show periods shorter than 5 min and exhibit a clear seasonal pattern with enhanced activity during equinoxes. To investigate the link between WFs and Gravity Waves (GWs) activity, we analyze two case studies (August 23, 2008, and January 2, 2009), during which WFs with similar periods appear nearly simultaneously along NAA-PLO and NAA-PIU propagation paths. For these events, GWs activity in the lower and upper ionosphere was examined using atmospheric temperature profiles from the TIMED/SABER satellite and GPS-derived Total Electron Content (TEC) data, both recorded near the VLF propagation paths. The analysis of TEC data reveals GWs with periods between 10 and 17 min, consistent with those identified in the VLF signals. Temperature profiles show GWs signatures with vertical wavelengths centered at 4–6 km and 12–14 km, predominantly between 70 and 100 km altitudes that correspond to typical nighttime VLF reflection heights. These results suggest an association between the WFs observed in VLF amplitude signals and GWs activity in the ionosphere under nighttime and solar minimum conditions.
利用NAA（美国缅因州Cutler， f = 24 kHz）和NDK（美国北达科他州LaMoure， f = 25.2 kHz）站点发送的极低频（VLF）窄带信号，研究了太阳活动极小期（2008-2009）夜间较低电离层波浪波动（WFs）的发生情况，这些信号分别记录在两个秘鲁站点PLO（利马）和PIU（皮乌拉）。这些传播路径主要跨越低纬度地区，并表现出相似的特征，因为它们是准平行的，可以在类似的地球物理和地磁条件下进行可靠的比较。统计和小波谱分析显示，在所有VLF传播路径上，WFs每天都持续存在，优势周期在10到15分钟之间。第二常见的WFs周期短于5分钟，并表现出明显的季节性模式，在春分时活动增强。为了研究WFs与引力波（GWs）活动之间的联系，我们分析了两个案例（2008年8月23日和2009年1月2日），在此期间，具有相似周期的WFs几乎同时出现在NAA-PLO和NAA-PIU传播路径上。对于这些事件，使用TIMED/SABER卫星的大气温度剖面和gps衍生的总电子含量（TEC）数据检查了低层和高层电离层的GWs活动，两者都记录在VLF传播路径附近。TEC数据分析显示周期在10至17分钟之间的gw，与VLF信号中确定的一致。温度剖面显示，GWs的垂直波长以4-6 km和12-14 km为中心，主要在70 - 100 km高度之间，对应典型的夜间VLF反射高度。这些结果表明，在夜间和太阳极小期条件下，在VLF振幅信号中观测到的WFs与电离层中的GWs活动之间存在关联。
{"title":"Characterization of short-period VLF amplitude fluctuations associated with gravity waves at low latitudes","authors":"Jorge Samanes , Alejandra Hinostroza Caldas , R.Y.C. Cueva , Emilia Correia","doi":"10.1016/j.asr.2025.11.095","DOIUrl":"10.1016/j.asr.2025.11.095","url":null,"abstract":"<div><div>We investigate the occurrence of wave-like fluctuations (WFs) in the nighttime lower ionosphere during solar minimum conditions (2008–2009) using Very Low Frequency (VLF) narrowband signals transmitted from NAA (US Cutler, Maine, <em>f</em> = 24 kHz) and NDK (US LaMoure, North Dakota, <em>f</em> = 25.2 kHz) stations and recorded at two Peruvian stations PLO (Lima) and PIU (Piura). These propagation paths span predominantly low-latitude regions and exhibit similar characteristics, as they are quasi-parallel, enabling reliable comparisons under similar geophysical and geomagnetic conditions. Statistical and wavelet spectral analysis reveal a persistent daily presence of WFs, with dominant periods between 10 and 15 min across all VLF propagation paths. The second most frequent WFs show periods shorter than 5 min and exhibit a clear seasonal pattern with enhanced activity during equinoxes. To investigate the link between WFs and Gravity Waves (GWs) activity, we analyze two case studies (August 23, 2008, and January 2, 2009), during which WFs with similar periods appear nearly simultaneously along NAA-PLO and NAA-PIU propagation paths. For these events, GWs activity in the lower and upper ionosphere was examined using atmospheric temperature profiles from the TIMED/SABER satellite and GPS-derived Total Electron Content (TEC) data, both recorded near the VLF propagation paths. The analysis of TEC data reveals GWs with periods between 10 and 17 min, consistent with those identified in the VLF signals. Temperature profiles show GWs signatures with vertical wavelengths centered at 4–6 km and 12–14 km, predominantly between 70 and 100 km altitudes that correspond to typical nighttime VLF reflection heights. These results suggest an association between the WFs observed in VLF amplitude signals and GWs activity in the ionosphere under nighttime and solar minimum conditions.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3578-3593"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081533","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}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.024
Qingzhi Zhao , Pengfei Geng , Zufeng Li , Yibin Yao , Yatong Li , Xiaohua Fu , Qiong Wu
With the rapid development of the numerical weather prediction (NWP) model and atmospheric water vapor detection technology, high-precision, high-resolution meteorological data can now be accurately obtained in specific regions. However, given the high temporal and spatial variability of precipitation, accurately estimating it on the basis of the NWP model is difficult. In view of the low accuracy of NWP grid precipitation and the low spatial resolution of station observation precipitation, this study proposes a correction–fusion method for NWP precipitation that considers multiple environmental information and combines the weather research and forecasting (WRF) model grid precipitation and station observation precipitation to obtain high-resolution, high-precision precipitation products. Results show that the accuracy of the merged precipitation data at four rainfall stations is better than that of WRF precipitation. The average improvement rates of the correlation coefficient and root-mean-square error are 32.7 % and 25.9 %, respectively. In addition, the merged precipitation product has a strong ability to capture the occurrence time of precipitation, and its average probability of detection at four rainfall stations reaches 0.99. The merged precipitation product has a good improvement effect on 12-h accumulated light rain, moderate rain, heavy rain, and torrential rain, and its improvement rate reaches 32.5 %, 39.6 %, 36.7 %, and 0.5 %, respectively. The WRF-Hydro model driven by merged precipitation effectively depicts the rainfall–runoff process curves, and the accuracy of streamflow simulation is improved, indicating that the merged precipitation product has good hydrological utility.
{"title":"Correction–fusion of NWP precipitation conditioned by rainfall stations and multivariate environmental information","authors":"Qingzhi Zhao , Pengfei Geng , Zufeng Li , Yibin Yao , Yatong Li , Xiaohua Fu , Qiong Wu","doi":"10.1016/j.asr.2025.11.024","DOIUrl":"10.1016/j.asr.2025.11.024","url":null,"abstract":"<div><div>With the rapid development of the numerical weather prediction (NWP) model and atmospheric water vapor detection technology, high-precision, high-resolution meteorological data can now be accurately obtained in specific regions. However, given the high temporal and spatial variability of precipitation, accurately estimating it on the basis of the NWP model is difficult. In view of the low accuracy of NWP grid precipitation and the low spatial resolution of station observation precipitation, this study proposes a correction–fusion method for NWP precipitation that considers multiple environmental information and combines the weather research and forecasting (WRF) model grid precipitation and station observation precipitation to obtain high-resolution, high-precision precipitation products. Results show that the accuracy of the merged precipitation data at four rainfall stations is better than that of WRF precipitation. The average improvement rates of the correlation coefficient and root-mean-square error are 32.7 % and 25.9 %, respectively. In addition, the merged precipitation product has a strong ability to capture the occurrence time of precipitation, and its average probability of detection at four rainfall stations reaches 0.99. The merged precipitation product has a good improvement effect on 12-h accumulated light rain, moderate rain, heavy rain, and torrential rain, and its improvement rate reaches 32.5 %, 39.6 %, 36.7 %, and 0.5 %, respectively. The WRF-Hydro model driven by merged precipitation effectively depicts the rainfall–runoff process curves, and the accuracy of streamflow simulation is improved, indicating that the merged precipitation product has good hydrological utility.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 2922-2935"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081821","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}
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