Yannick Sztamfater-Garcia, Manuel Sanjurjo-Rivo, Guillermo Escribano, Harold Molina-Bulla, Joaquin Miguez
{"title":"An approximate model for the computation of in-orbit collision probabilities using importance sampling","authors":"Yannick Sztamfater-Garcia, Manuel Sanjurjo-Rivo, Guillermo Escribano, Harold Molina-Bulla, Joaquin Miguez","doi":"10.1016/j.asr.2024.12.074","DOIUrl":"10.1016/j.asr.2024.12.074","url":null,"abstract":"<div><div>The risk of orbital collisions is at an all-time high. Standard methods which compute the probability of collision (PoC) often make restrictive assumptions which produce numerically efficient solutions, the quality of which may decrease over long time-spans. The crude Monte Carlo (CMC) simulation makes few assumptions and can produce high quality estimates; however, its computational cost can be prohibitively high. We introduce a new method based on importance sampling (IS), which aims to attain the accuracy of a CMC simulation at a fraction of the computational cost. To accomplish this, we propose a surrogate dynamical model which exploits Keplerian conjunction geometry and applies a linear correction to approximate the full-dynamics of the conjunction scenario, reducing the computational load of evaluating the dynamical model. This linear approximation is satisfactorily validated by means of high-fidelity model evaluations. The PoC results, when the method is applied on LEO and GEO scenarios, show agreement with an independent CMC benchmark simulation for the calculation of the PoC at a fraction of the computational cost.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3791-3805"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaodan Liu , Yan Li , Henghui Xi , Xiaohong Li , Yiyang Wu , Shirui Yuan , Muwu Xu , Weixin Ou , Conghong Huang
{"title":"Assessing spatial pattern of urban green space coverage and its determining factors: A case study in the Yangtze River Delta region in China","authors":"Xiaodan Liu , Yan Li , Henghui Xi , Xiaohong Li , Yiyang Wu , Shirui Yuan , Muwu Xu , Weixin Ou , Conghong Huang","doi":"10.1016/j.asr.2024.12.009","DOIUrl":"10.1016/j.asr.2024.12.009","url":null,"abstract":"<div><div>Information on green space coverage patterns and influencing factors in built-up areas is essential for urban planners, as it is related to the well-being of residents. In this study, WorldCover land cover product was used to extract green space maps and analyze landscape patterns of urban green space coverage (UGSC) of built-up areas in China’s Yangtze River Delta region under different scales (i.e., built-up area, district/county, and prefecture-level city) in 2020. Additionally, cold and hot spot analyses were performed to represent the regional aggregation of high and low green space coverage. The random forest model was used to calculate the relative importance and marginal effect of the factors influencing UGSC. The results show that, in general, the UGSC gradually decreases from the southern to the northern regions. The pattern of UGSC is basically the same as that of tree/shrub coverage. Precipitation, the size of built-up area, and the area of urban paved roads are the main influencing factors of UGSC. Nonlinear relationships are observed between the size of built-up areas and UGSC, as well as between the area of urban paved roads and UGSC. The detailed mapping of the UGSC pattern and identifying key influencing factors offer valuable insights for urban planning and sustainable development.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3362-3374"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403040","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":"Successes, misses and false alarms in predicting global/seasonal equatorial plasma bubble occurrences with the ROCSAT data","authors":"S.-Y. Su , H.-H. Ho , C.-K. Chao , C.H. Liu","doi":"10.1016/j.asr.2024.12.067","DOIUrl":"10.1016/j.asr.2024.12.067","url":null,"abstract":"<div><div>The density variations at a constant height such as observed by the circularly orbiting ROCSAT-1 spacecraft are studied to construct a “prediction model” for the occurrences, no-occurrences, misses and false alarms of global/seasonal equatorial plasma bubble (EPB) occurrences. This global/seasonal prediction model is different from previous studies that merely provide the seasonal EPB occurrence probability at a local time region or globally. The current model uses the density increment above the seasonal mean to predict the EPB occurrences by constructing a contingency table that counts the numbers of successes, fails, misses, and false alarms in predicting the EPB occurrences. Different thresholds of density increment are used for the criteria in prediction to obtain an optimal result in the prediction model. The success of the model for predicting the global EPB occurrences or no-occurrences varies between 75% and 85% for any season between 1999 and 2004 during the moderate to high solar activity period. Studies of the causes for the misses and false alarms in the existing prediction result lead us to propose that additional observational parameter besides the density increment in the prediction model should be included. This additional parameter should be the seeding agent for the RTI process that related to the atmospheric/ionospheric background conditions in the lower ionosphere.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3589-3600"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Infrared properties of Planetary Nebulae with PG1159 central stars","authors":"C. Muthumariappan , K. Khushbu , V. Kerni","doi":"10.1016/j.asr.2024.12.032","DOIUrl":"10.1016/j.asr.2024.12.032","url":null,"abstract":"<div><div>We study the properties of 26 PNe with PG1159-type central stars known till date and compare them with the properties of PNe having [WR], <em>wels</em> and hydrogen-rich central stars published earlier. We use archival photometric measurements of <span><math><mrow><mn>2</mn><mi>MASS</mi></mrow></math></span> for near-IR analysis and <em>WISE</em> and <em>IRAS</em> data for mid- and far-IR analysis and derive the IR properties of PG1159-PNe. We analyze the IR colour-colour diagrams of PG1159-PNe and compare them with the other three groups of PNe. Similar to the [WR]-PNe, many PG1159-PNe also show large amount of near-IR emission from the hot-dust component but their AGB dust is relatively cooler. We also report here the dust colour temperatures, dust masses, dust-to-gas mass ratios, IR luminosities and IR excess of PG1159-PNe and plot them against their surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness (age) and compare them with the distribution of other groups of PNe. The IR luminosity and dust temperature show strong correlation with surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness, however, the dust-to-gas mass ratio and IR excess do not show any trend. While the mean dust mass has a lower value for PG1159-PNe, in compared to other groups, the average dust-to-gas mass ratio is found to be marginally larger for PG1159-PNe. An analysis of the number distribution of different groups of PNe against surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness shows that a) younger [WR]-, <em>wels</em>- and normal-PNe have a similar distribution indicating that they all have evolved from the AGB in a similar way, b) while there is an overlap of surface H<span><math><mrow><mi>β</mi></mrow></math></span> brightness between [WR]- and PG1159-PNe, showing an evolutionary connection between them, there exists a significant gap between the values derived for <em>wels</em>- and PG1159-PNe.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 4126-4140"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402781","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}
Huihui Feng , Shu Wang , Shijie Li , Wei Wang , Jingya Li , Runxi Gu , Jixian Huang
{"title":"Satellite-based re-examination of global soil moisture variation","authors":"Huihui Feng , Shu Wang , Shijie Li , Wei Wang , Jingya Li , Runxi Gu , Jixian Huang","doi":"10.1016/j.asr.2024.12.030","DOIUrl":"10.1016/j.asr.2024.12.030","url":null,"abstract":"<div><div>It was crucial to capture the variation in global soil moisture for exploring the global eco-hydrological processes. Based on the global soil moisture data from the Climate Change Initiative (CCI) published by the European Space Agency (ESA), this study re-examined the spatial pattern and temporal trend of global soil moisture from 1978 to 2021. Our results showed that the global mean soil moisture was 0.208 cm<sup>3</sup>·cm<sup>−3</sup>, which showed a weak decreasing trend over the past four decades <strong>(</strong>−1.2 × 10<sup>-4</sup> cm<sup>3</sup>·cm<sup>−3</sup> yr<sup>−1</sup>, <em>R<sup>2</sup></em> = 0.23, <em>p</em> = 0.001<strong>)</strong>. Spatially, about 12.99 % of the land showed a significant drying trend, while only 6.74 % of the land showed a wetting trend. However, in the last decade, global soil moisture exhibited a distinct upward trend (7 × 10<sup>-4</sup> cm<sup>3</sup>·cm<sup>−3</sup> yr<sup>−1</sup>, <em>R<sup>2</sup></em> = 0.87, <em>p</em> = 0.000). Specifically, during this period, 5.72 % of the land showed a marked drying tendency, while 9.09 % of the land displayed a wetting trend. Soil moisture variation in the arid climate zones showed a negative contribution to the global trend, with the total contribution of −45.72 %. In contrast, soil moisture trends in temperate and cold climate zones mainly exerted positive contributions to the global trend. From a continental perspective, Asia’s positive contribution was the most significant, accounting for 39.96 %, whereas North America showed a significant negative contribution of −37.43 %. Temporally, the negative maximum change in soil moisture occurs in June-August and the positive maximum change occurs in September-November, serving as the predominant d river for the annual trend. Results of this study helped to clarify the variation of global soil moisture, which could support the sustainable water management in the changing climate.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3486-3495"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402861","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}
Jinsheng Tu , Xiufeng He , Xiaolei Wang , Minfeng Song , Zhixiang Yang
{"title":"Detecting surface subsidence trends in permafrost areas with undulating terrains using GPS interferometric reflectometry","authors":"Jinsheng Tu , Xiufeng He , Xiaolei Wang , Minfeng Song , Zhixiang Yang","doi":"10.1016/j.asr.2024.12.033","DOIUrl":"10.1016/j.asr.2024.12.033","url":null,"abstract":"<div><div>Global navigation satellite system interferometric reflectometry (GNSS-IR) technology has been applied to detect surface deformation in permafrost areas. Affected by terrain, previous studies have mainly focused on GNSS sites located in permafrost areas with uniform flat surfaces; however, the number of sites is small, which limits the expansion of regional research. This study provides ideas for the detection of surface subsidence trends in permafrost areas with undulating terrains using global positioning system (GPS) interferometric reflectometry. We selected the GPS site AB33 in Coldfoot, Alaska, and the GPS signal-to-noise ratio (SNR) data during the 2023 snow-free thaw season were processed to obtain continuous surface reflector heights. Outlier detection of reflector heights to extract robust and reliable information and reflector height change trends were analyzed to identify satellite results of detected surface subsidence trends. Thereafter, hierarchical clustering was performed by azimuth and reflector height to group the satellite results into similar clusters and average them. Finally, the correlation between the surface subsidence trends detected at different azimuth ranges after clustering and the subsidence trends simulated by the thawing index was analyzed. The results showed that the detected surface subsidence trends strongly correlated with the simulated trends, with a maximum correlation coefficient (R) of 0.74. This verifies that the ideas presented in this study can effectively detect surface subsidence trends in permafrost areas with undulating terrains.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3496-3506"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402862","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 new methodology for determining the long-term behavior of earth surface deformations from InSAR results","authors":"Yavuz Gül , Kemal Özgür Hastaoğlu , Fatih Poyraz","doi":"10.1016/j.asr.2024.12.035","DOIUrl":"10.1016/j.asr.2024.12.035","url":null,"abstract":"<div><div>The InSAR method is an effective method of presenting the temporal change and behavior characteristics of surface deformations to users and monitoring deformations. In general, it is possible to determine the spatial distribution and magnitude of surface deformations using InSAR analysis results. However, more detailed analyses should be performed to reveal and interpret the long-term behavior of deformations from these results. It is especially important to classify deformation velocities and present the temporal change and behavior characteristics of deformations by analyzing the densities of these classes and their periodic changes. This study developed a new methodology and software to present the temporal change and behavior characteristics of deformations to users. With the new methodology and software developed, values such as time-dependent increasing/decreasing trend of deformations, continuity, velocity value and class, and areal ratio/density can be determined and long-term behavior characteristics of deformations can be revealed. It is possible to make more reliable predictions of future behavior by considering the current increasing or decreasing trend of deformation behavior. The methodology and software developed were used to monitor surface deformations at the dump site of Kangal/Kalburçayırı open-pit coal mine, and the results were discussed. Owing to the method developed, deformation behavior was determined, and the prospective support heel precaution was taken. The new situation and deformation behavior that occurred as a result of this precaution were examined with the same methodology and software, and the success of the support heel was discussed.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3521-3540"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403140","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":"Flood risk assessment in Ténès city (Algeria) using land cover based on machine learning methods and Pléiades tri-stereo images","authors":"Zaabar Narimane , Niculescu Simona , Mihoubi Mustapha Kamel","doi":"10.1016/j.asr.2024.12.036","DOIUrl":"10.1016/j.asr.2024.12.036","url":null,"abstract":"<div><div>On a global scale, a considerable amount of life, property, and resources are lost because of the increasing frequency and severity of flooding occurrences. This necessitates worldwide development, thorough flood risk assessments and urbanization policies. This work used sophisticated remote sensing data and hydraulic models to create an effective and appropriate methodology for flood risk assessment in a coastal city located in western Algeria. In the first stage, Sentinel-2 optical data was classified using deep learning and machine learning methods for land cover and land use (LULC). The CNN deep model based on LULC was selected for its outstanding overall accuracy. Then, a 1-D HEC-RAS hydraulic model was performed, integrating LULC maps with a higher precision, topography using a digital surface model (DSM) derived from Pléiades tri-stereo data, and another digital elevation model (12 m). Flood hydrographs were also constructed for four scenarios (10, 20, 50, and 100 years) using hydrometric data. The 1D flood model was indeed validated using a flood event data. Flood hazard, LULC and flood risk maps were derived. Results show the high flood hazard areas are concentrated on the left bank of the Oued Allala River and urban cities near the coast. According to the results of the flood hazard simulation of 100 years, built-up areas and roads are the LULC classes most affected by flood hazard, with more than 94.4 % and 69.34 % for DSM tri-stereo and DEM models, respectively. As well, results of flood risk assessment by combining hazard risk and LULC vulnerability show that for the DSM model, 0.48 %, 44.55 %, and 53.11 %, and 54.04 % of flooded areas are in low, medium, and high flood risk, respectively. For the DEM model, 3.14 %, 45 %, and 51.04 % of flooded areas are in low, medium, and high flood risk, respectively. Results confirmed that topographic resolution models and LULC accuracy of CNN models can highly affect hydraulic simulation output results. Based on the obtained results, Ténès City needs necessary planning for flood risk management, particularly in the coastal area. Derived maps can serve as valuable information for regional and national decision-making.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3541-3564"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403141","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":"Phase space deep neural network with Saliency-based attention for hyperspectral target detection","authors":"Maryam Imani , Daniele Cerra","doi":"10.1016/j.asr.2024.12.037","DOIUrl":"10.1016/j.asr.2024.12.037","url":null,"abstract":"<div><div>The accurate separation of targets and background is challenging in hyperspectral target detection algorithms, due to the high variability and complex non-linear scattering interactions in spectra acquired by imaging spectrometers. Moreover, the target regions may be contaminated by the background signal in real images, hindering the separation of a specific target in a scene. To address these challenges, a deep neural network is proposed in this work, consisting of three modules. First, to extract features hidden in the spectral signature of pixels, the hyperspectral image is considered as a dynamic system, and its phase space is reconstructed in the spectral feature space. Subsequently, in order to highlight the targets and suppress the background, a saliency map is produced, which shows candidate regions for the targets of interest. The saliency map is then utilized as an attention map for weighting the hyperspectral input within the network. The proposed multi-branch deep neural network processes each dimension of the reconstructed phase space. The resulting Phase Space Deep Neural Network with Saliency-based Attention (PSDNN-SA) outperforms several state-of-the-art detectors both quantitatively and visually in experiments carried out on different real hyperspectral subsets.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3565-3588"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403142","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}
Zhuang Chen , Xiaomin Luo , Xinmei Liang , Yujie Li , Yingzong Lin , Shaofeng Bian
{"title":"Comprehensive analysis of different GNSS receivers performance based on PPP-AR and positioning accuracy during 22 geomagnetic storms in 2023","authors":"Zhuang Chen , Xiaomin Luo , Xinmei Liang , Yujie Li , Yingzong Lin , Shaofeng Bian","doi":"10.1016/j.asr.2024.11.067","DOIUrl":"10.1016/j.asr.2024.11.067","url":null,"abstract":"<div><div>Geomagnetic storms induced ionospheric disturbances can degrade the positioning accuracy and Ambiguity Resolution (PPP-AR) of GPS Precise Point Positioning (PPP), and this negative effect varies among different GNSS receivers. Under current conditions with frequent geomagnetic storms occurrences during the peak of solar cycle 25, selecting GNSS receivers with strong resistance to ionospheric disturbances is meaningful for precise GNSS positioning and ionospheric research. Therefore, it is necessary to conduct a comprehensive comparison and evaluation of the performance for different GNSS receivers under geomagnetic storms. Based on 22 geomagnetic storms in 2023, we investigated the three-dimensional root mean square error (3D RMS) and ambiguity resolved percentage (ARP), which is defined as the ratio of the number of carrier-phase observations with fixed ambiguities to the total number of phase measurements of GPS kinematic PPP, across ten groups of collocated stations around the world. For the groups using different receiver brands, the performance ranking for positioning accuracy and PPP-AR during geomagnetic storms are as follows: TPS > JVAVD > SEPTENTRIO > TRIMBLE. The station with a larger average ARP generally has a smaller average 3D RMS error than the another GNSS station. The average 3D RMS error between collocated stations using different receiver brands is typically greater than 0.010 m and even larger. The largest 3D RMS error difference is observed between collocated stations with SEPTENTRIO and JAVAD receivers, with 3D RMS errors of 0.089 m and 0.019 m, respectively. These identical-brand receivers with different types are as follows: TPS NET-G5 > TPS NET-G3A, TRIMBLE ALLOY > TRIMBLE NETRS, SEPT POLARX5TR > SEPT POLARX5S, and LEICA GR10 > LEICA GR30, respectively. The average differences in 3D RMS and ARP can reach up to 0.021 m and 6.0 %, respectively. We found that the choice of antennas does not significantly affect PPP positioning performance during storms, with differences in average 3D RMS below 0.005 m and ARP differences below 0.2 %.. Higher latitudes have more satellites affected by ionospheric disturbances, while this effect is typically only observed during strong storms (<span><math><mrow><msub><mrow><mi>Dst</mi></mrow><mrow><mi>min</mi></mrow></msub><mo>≤</mo><mo>-</mo><mn>100</mn><mi>n</mi><mi>T</mi></mrow></math></span>) in mid-latitudes. Adequate available GPS satellites are crucial for achieving high PPP-AR and positioning accuracy during storms. The variations of disturbed satellites and the average Rate of Total Electron Content Index (ROTI) for collocated stations are generally consistent. However, there are differences in the average of ROTI values for different receivers under geomagnetic storms. The differences in PPP-AR performance and ROTI values among different receivers under geomagnetic storms can be attributed to the variations in satellite tracking algorithms, tracking loo","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3630-3650"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403146","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}