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Assessment of International GNSS Service Global Ionosphere Map products over China region based on measurements from the Crustal Movement Observation Network of China

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earth and Planetary Physics 2024年第2期8卷 400-407页

作者： Jin Hu HaiBing Ruan FuQing Huang ShengYang Gu XianKang Dou institute of space Weather Nanjing University of Information Science and TechnologyNanjing 210044China State Key Laboratory of space Weather Chinese Academy of Sciences(CAS)Beijing 100190China School of Electronic information Wuhan UniversityWuhan 430072China Wuxi Research institute Nanjing University of Information Science and TechnologyWuxi Jiangsu 214000China CAS Key Laboratory of Geospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China

The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical *** the credibility of GIM products in data-sparse regions is of paramount *** this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in *** indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM *** revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error *** results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions.

关键词： International GNSS Service(IGS)Global Ionosphere Maps(GIM) Crustal Movement Observation Network of China(CMONOC) total electron content(TEC) data assessment

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Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1192-1201页

作者： Yu Feng Ke Gao Suzanne Lacasse Norwegian Geotechnical institute OsloNorway Department of earth and space sciences Southern University of Science and TechnologyShenzhenChina

The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste *** one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC ***,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC *** address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement ***,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC *** performed five case studies using OC test data made at a nuclear waste repository research site of *** results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.

关键词： Overcoring stress measurement Uncertainty reduction Partial pooling Bayesian hierarchical model Nuclear waste repository

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Scientific objectives and payload configuration of the Chang'E-7 mission

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National Science Review 2024年第2期11卷 285-300页

作者： Chi Wang Yingzhuo Jia Changbin Xue Yangting Lin Jianzhong Liu Xiaohui Fu Lin Xu Yun Huang Yufen Zhao Yigang Xu Rui Gao Yong Wei Yuhua Tang Dengyun Yu Yongliao Zou State Key Laboratory of space Weather National Space Science Center Chinese Academy of Sciences National space Science Center Chinese Academy of Sciences institute of Geology and Geophysics Chinese Academy of Sciences institute of Geochemistry Chinese Academy of Sciences Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and Physics Institute of Space SciencesShandong University institute of Drug Discovery Technology Ningbo University State Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences School of earth Science and Engineering Sun Yat-sen University Lunar Exploration and space Engineering Center China Aerospace Science and Technology Corporation

As the cornerstone mission of the fourth phase of the Chinese Lunar Exploration Program, Chang'E-7(CE-7) was officially approved, and implementation started in 2022, including a main probe and a communication relay satellite. The main probe, consisting of an orbiter, a lander, a rover and a mini-flying probe, is scheduled to be launched in 2026. The lander will land on Shackleton crater's illuminated rim near the lunar south pole, along with the rover and mini-flying probe. The relay satellite(named Queqiao-2) will be launched in February 2024 as an independent mission to support relay communication during scientific exploration undertaken by Chang'E-4, the upcoming Chang'E-6 in 2024 and subsequent lunar *** CE-7 mission is mainly aimed at scientific and resource exploration of the lunar south pole. We present CE-7's scientific objectives, the scientific payloads configuration and the main functions for each scientific payload with its key technical specifications.

关键词： Chang’ E-7 scientific objectives scientific payloads

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Extreme value theory applied to the auroral electrojet indices

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earth and Planetary Physics 2024年第2期8卷 375-381页

作者： Si Chen Hong Yuan Yong Wei Guang Yang FengZheng Yu Aerospace information Research institute Chinese Academy of SciencesBeijing 100094China Key Laboratory of earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China

The study of extreme weather and space events has gained paramount importance in modern society owing to rapid advances in high *** and describing exceptional occurrences plays a crucial role in making decisive assessments of their potential impact on technical,economic,and social aspects in various *** research focuses on analyzing the hourly values of the auroral electrojet(AE)geomagnetic index from 1957 to 2019 by using the peak over threshold method in extreme value *** fitting the generalized Pareto distribution to extreme AE values,shape parameter indices were derived,revealing negative values that establish an upper bound for this time ***,it became evident that the AE values had reached a plateau,suggesting that extreme events exceeding the established upper limit are *** a result,although the need for diligent precautions to mitigate the consequences of such extreme events persists,surpassing the upper limit of AE values becomes increasingly *** is also possible to observe an aurora in the middle-and low-latitude regions during the maximum period of the AE index.

关键词： auroral electrojet indices extreme value theory extreme events

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Characterizing extreme drought and wetness in Guangdong,China using global navigation satellite system and precipitation data

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Satellite Navigation 2024年第1期5卷 258-274页

作者： Hai Zhu Kejie Chen Haishan Chai Yuanbin Ye Wenjian Liu Department of earth and space sciences Southern University of Science and TechnologyShenzhen518055China Lands and Resource Department of Guangdong Province Surveying and Mapping InstituteGuangzhou510500China

As global temperature rises,the frequency of extreme climate events,e.g.,severe droughts and floods,has increased significantly and caused severe damage over the past *** this regard,precipitation efficiency,a crucial meteorological parameter,could provide valuable insights for a better understanding of the patterns and characteristics of these extreme *** this study,taking Guangdong province as an exemplary region,we first obtained long-term and high-resolution historical records of precipitation efficiency by integrating the observations from a dense network of Global Navigation Satellite System(GNSS)stations with precipitation data,and then characterized the extreme drought and wetness through climate *** found a distinct seasonal trend in precipitation efficiency in Guangdong,with annual fluctuations ranging from 10 to 25%.Notably,precipitation efficiency is higher in proximity to the Pearl River Delta Plain and gradually decreases towards the east and *** occurrence of anomalous peaks and valleys in precipitation efficiency generally corresponds to dry and wet conditions,respectively.A total of 9 extreme wet events and 6 dry events occurred from January 2007 to May 2022,with durations from 3 to 6 *** results also demonstrated that both wet and dry frequencies exhibit an increasing trend with the expansion of the time scale,and the frequency of extreme events near the Pearl River Delta Plain surpasses that of other ***,the propagation time from meteorological anomalies to agricultural and hydrological anomalies is about 3 *** periodic characteristics of meteorological anomalies are identified as the primary driver for other anomalous periodic *** work unveils the long-term dynamic behavior of precipitation efficiency,as well as the characteristics of extreme drought and wetness events in the regions characterized by intricate land–atmosphere interactions.

关键词： GNSS Precipitation efficiency Extreme drought and wetness

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Three-stage niobium mineralization at Bayan Obo, China

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National Science Review 2024年第4期11卷 102-110页

作者： Yan Yu Yang Li Yu Liu Xiao-Xiao Ling Li-Guang Wu Li Yang Lan Yang Bo Yang Yong-Gang Zhao Xian-Hua Li State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences College of earth and Planetary Science University of Chinese Academy of Sciences Ministry of Education Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking University Mining Research institute Baotou Iron and Steel(Group) Co.LTD State Key Laboratory of Baiyunobo Rare earth Resource Research and Comprehensive Utilization

The Chinese Bayan Obo deposit is a world-class rare earth element(REE) deposit with considerable niobium(Nb) and iron(Fe) resources. A complete genetic understanding on all metals is fundamental for establishing genetic models at Bayan Obo. With extensive research being focused on REE enrichment, the timing and controls of Nb enrichment remain unresolved at Bayan Obo, which is mainly due to the challenges in dating, i.e. multistage thermal events, fine-grained minerals with complex textures and the rare occurrence of uranium-enriched minerals with mature dating methods. Based on robust geological and petrographic frameworks, here we conducted ion probe uranium-lead(U-Pb) dating of ferrocolumbite to unravel the timing, hence the genesis of Nb mineralization. Three types of hydrothermal ferrocolumbites—key Nb-bearing minerals—are identified based on their textures and mineral assemblages. They yield U-Pb ages of 1312 ± 47 Ma(n = 99), 438 ± 7 Ma(n = 93), and 268 ± 5 Ma(n = 19), respectively. In line with deposit geology, we tentatively link the first, second and third stage Nb mineralization to Mesoproterozoic carbonatite magmatism, ubiquitous early Paleozoic hydrothermal activity, and Permian granitic magmatism, respectively. While quantifying the contribution of metal endowment from each stage requires further investigation, our new dates highlight that multi-stage mineralization is critical for Nb enrichment at Bayan Obo, which may also have implications for the enrichment mechanism of Nb in REE deposits in general.

关键词： niobium mineralization U-Pb dating ferrocolumbite Bayan Obo

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Comparison of the Minimum Bounding Rectangle and Minimum Circumscribed Ellipse of Rain Cells from TRMM

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Advances in Atmospheric sciences 2024年第3期41卷 391-406页

作者： Hongke CAI Yaqin MAO Xuanhao ZHU Yunfei FU Renjun ZHOU Plateau Atmospheric and Environment Laboratory of Sichuan Province School of Atmospheric SciencesChengdu University of Information TechnologyChengdu 610225China School of earth and space sciences University of Science and Technology of ChinaHefei 230026China Center for Atmospheric Optics Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China

Based on the TRMM dataset, this paper compares the applicability of the improved MCE(minimum circumscribed ellipse), MBR(minimum bounding rectangle), and DIA(direct indexing area) methods for rain cell fitting. These three methods can reflect the geometric characteristics of clouds and apply geometric parameters to estimate the real dimensions of rain cells. The MCE method shows a major advantage in identifying the circumference of rain cells. The circumference of rain cells identified by MCE in most samples is smaller than that identified by DIA and MBR, and more similar to the observed rain cells. The area of rain cells identified by MBR is relatively robust. For rain cells composed of many pixels(N> 20), the overall performance is better than that of MCE, but the contribution of MBR to the best identification results,which have the shortest circumference and the smallest area, is less than that of MCE. The DIA method is best suited to small rain cells with a circumference of less than 100 km and an area of less than 120 km^(2), but the overall performance is mediocre. The MCE method tends to achieve the highest success at any angle, whereas there are fewer “best identification”results from DIA or MBR and more of the worst ones in the along-track direction and cross-track direction. Through this comprehensive comparison, we conclude that MCE can obtain the best fitting results with the shortest circumference and the smallest area on behalf of the high filling effect for all sizes of rain cells.

关键词： TRMM minimum bounding rectangle minimum circumscribed ellipse

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Influence of self-similar stresses on scenario earthquake construction:An example along the Tanlu Fault

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Science China earth sciences 2024年第5期67卷 1687-1697页

作者： Feng HU Huajian YAO Houyun YU Zeyu LU Jieyi HOU Song LUO Zhigang SHAO Xiaofei CHEN School of earth and space sciences University of Science and Technology of ChinaHefei 230026China Mengcheng Geophysical National Field Scientific Observatory Hefei 230026China Department of earth and space Science Southern University of Science and TechnologyShenzhen 518055China institute of earthquake Prediction China Earthquake AdministrationBeijing 100036China

As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern *** is important to improve the understanding of seismic hazard assessments in areas near *** start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu *** fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake *** the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation *** findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake *** compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial *** the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip *** response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.

关键词： Scenario earthquakes Self-similar stress Tanlu Fault Dynamic rupture Ground motion

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Global convergence in terrestrial gross primary production response to atmospheric vapor pressure deficit

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Science China Life sciences 2024年第9期67卷 2016-2025页

作者： Chao Huang Jingfeng Huang Jingfeng Xiao Xing Li Hong S.He Yu Liang Fusheng Chen Hanqin Tian Key Laboratory of National Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of Forestry Jiangxi Agricultural University CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences institute of Applied Remote Sensing & information Technology College of Environmental and Resource Sciences Zhejiang University Key Laboratory of Agricultural Remote Sensing and information Systems Zhejiang Province Zhejiang University earth Systems Research Center Institute for the Study of Earth Oceans and Space University of New Hampshire Research institute of Agriculture and Life sciences Seoul National University School of Natural Resources University of Missouri Schiller institute for Integrated Science and Society Department of Earth and Environmental Sciences Boston College

Atmospheric vapor pressure deficit（VPD） increases with climate warming and may limit plant growth. However, gross primary production（GPP） responses to VPD remain a mystery, offering a significant source of uncertainty in the estimation of global terrestrial ecosystems carbon dynamics. In this study, in-situ measurements, satellite-derived data, and earth System Models（ESMs） simulations were analysed to show that the GPP of most ecosystems has a similar threshold in response to VPD: first increasing and then declining. When VPD exceeds these thresholds, atmospheric drought stress reduces soil moisture and stomatal conductance, thereby decreasing the productivity of terrestrial ecosystems. Current ESMs underscore CO2fertilization effects but predict significant GPP decline in low-latitude ecosystems when VPD exceeds the thresholds. These results emphasize the impacts of climate warming on VPD and propose limitations to future ecosystems productivity caused by increased atmospheric water demand. Incorporating VPD, soil moisture, and canopy conductance interactions into ESMs enhances the prediction of terrestrial ecosystem responses to climate change.

关键词： atmospheric water demands soil moisture stomatal conductance photosynthesis climate warming.

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Segmental nature of the Red River fault revealed by seismic anisotropy and geological structures

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Science China earth sciences 2024年第8期67卷 2423-2443页

作者： Ying LI Yuan GAO School of earth and space sciences University of Science and Technology of ChinaHefei 230026China Key Laboratory of earthquake Prediction Institute of Earthquake ForecastingChina Earthquake AdministrationBeijing 100036China

As the western boundary of the Sichuan-Yunnan block(SYB),the Red River fault(RRF)is a major fault that controls deep crustal movement and deformation in the southeast margin of the Tibetan Plateau and regulates middle-lower crustal *** data suggest that the RRF is segmented and exhibits distinct variations in seismicity,velocity structure and crustal deformation from north to *** anisotropy reveals a complex pattern of lateral spatial and vertical stratified distributions.(1)From the perspective of crustal stratification,in the upper crust,the fast wave polarization in the north segment of the RRF is complex and possibly influenced by the Sanjiang lateral collision zone and adjacent faults with varying *** fast wave polarization in the middle segment is in the NW-SE direction,indicating a localized area of closed down or locked up with consistent *** in the south segment,it presents a disordered pattern,signifying complex deep tectonics and stress conditions at the wedged intersection *** the middle-lower crust in the north and south segments of the RRF,the azimuthal anisotropy is strong and consistent with the spatial strike of the weak zone characterized by low-velocity and *** suggests a connection between the anisotropy and the material migration.(2)In the whole crustal scale,the fast wave directions in two sides of the RRF are consistent with the NW-SE tectonic *** indicates that the RRF,as a large fault potentially cutting through the whole crust,strongly controls the surrounding media.(3)In the lithospheric scale,the fast wave polarizations are oriented nearly E-W and independent of the fault strike,consistent with the low P-and S-wave velocity structures and positive radial anisotropy in the upper *** fast wave directions could be related to lithospheric olivine deformation and asthenospheric *** paper suggests a decoupling of deformation between the crust and the lithospheri

关键词： Red River fault Seismic anisotropy Geological structures Lithosphere Fault segmentation

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