In this study, we provide a detailed case study of the X-pattern of equatorial ionization anomaly(EIA) observed on the night of September 12, 2021 by the Global-scale Observations of the Limb and Disk(GOLD) mission. U...In this study, we provide a detailed case study of the X-pattern of equatorial ionization anomaly(EIA) observed on the night of September 12, 2021 by the Global-scale Observations of the Limb and Disk(GOLD) mission. Unlike most previous studies about the X-pattern observed under the severely disturbed background ionosphere, this event is observed under geomagnetically quiet and low solar activity conditions. GOLD's continuous observations reveal that the X-pattern intensity evolves with local time, while its center's longitude remains constant. The total electron content(TEC) data derived from the ground-based Global Navigation Satellite System(GNSS) network aligns well with GOLD observations in capturing the formation of the X-pattern, extending coverage to areas beyond GOLD's observational reach. Additionally, the ESA's Swarm mission show that both sides of the X-pattern can coincide with the occurrence of small-scale equatorial plasma bubbles(EPBs). To further analyze the possible drivers of the X-pattern, observations from the Ionospheric Connection Explorer(ICON) satellite were used. It shows that the latitudinal expansion(or width) between the EIA crests in two hemispheres is proportional(or inversely proportional) to the upward(or downward) plasma drift velocity, which suggests that the zonal electric field should have a notable influence on the formation of EIA X-pattern. Further simulations using the SAMI2 model support this mechanism, as the X-pattern of EIA is successfully reproduced by setting the vertical plasma drift to different values at different longitudes.展开更多
湖泊沉积物作为重要的环境演化记录载体,其矿物组合特征蕴含了丰富的古环境信息。然而,由于沉积物中晶质和非晶质组分的复杂共存关系,以及多相矿物体系的相互干扰效应,其精确定量分析一直是沉积学研究中的技术难点。该研究以西藏中部封...湖泊沉积物作为重要的环境演化记录载体,其矿物组合特征蕴含了丰富的古环境信息。然而,由于沉积物中晶质和非晶质组分的复杂共存关系,以及多相矿物体系的相互干扰效应,其精确定量分析一直是沉积学研究中的技术难点。该研究以西藏中部封闭咸水湖泊巴木错沉积物为研究对象,系统分析、评估了参比强度比(RIR)法和Rietveld全谱拟合法在复杂沉积物矿物定量分析中的可靠性和应用效果。文章采用高纯度刚玉作为内标物质,设计了1∶1、3∶7和1∶9三组不同配比的混合样品,通过X射线衍射(XRD)分析获取了完整的衍射数据。基于COD晶体结构数据库,分别采用RIR值法和Rietveld全谱拟合法进行定量计算,并结合非晶含量测定方法,构建了完整的矿物定量分析体系。研究结果表明,Rietveld全谱拟合法表现出优异的分析精度和稳定性:对于含量大于20%的主量相,相对标准偏差(RSD,Relative Standard Deviation)控制在3%以内;含量在5%~20%之间的次量相,RSD值保持在5%~10%范围内;即使对于含量低于5%的微量相,其定量结果也显著优于RIR值法。特别是在处理非均质样品时,Rietveld法表现出良好的适应性,各矿物相含量与混合比例呈现显著的线性相关性(R^(2)>0.95)。相比之下,RIR值法在高含量内标条件下(50%和30%)表现出显著的不稳定性,定量结果的相对偏差超出了SY/T5163-2018标准规定的允许范围。这种局限性主要源于其对单个衍射峰强度比值的过度依赖,易受样品基体效应和优势相干扰的影响。此外,通过非晶含量计算,获得了原始沉积物样品中约31%的非晶态物质含量,三组混合样品计算结果的高度一致性(RSD<3%)进一步验证了Rietveld法的可靠性。该研究不仅系统评估了两种定量方法的适用性,而且在复杂湖泊沉积物分析中首次实现了晶质矿物和非晶质组分的协同定量。研究结果对完善湖泊沉积物矿物定量分析方法,提高环境重建的准确性具有重要意义和应用价值。展开更多
通过使用RFPA(Rock Failure Process Analysis System)二维模拟软件,分别研究了断层相交角度θ、破碎带宽度、关键层强度、破碎带强度、埋深5个参数对X型正断层交汇处垂直和水平方向应力场分布的影响。研究表明,这些因素在不同范围内,...通过使用RFPA(Rock Failure Process Analysis System)二维模拟软件,分别研究了断层相交角度θ、破碎带宽度、关键层强度、破碎带强度、埋深5个参数对X型正断层交汇处垂直和水平方向应力场分布的影响。研究表明,这些因素在不同范围内,都对断层交汇处地应力场的分布有不同程度的影响,且这些因素对垂直和水平两个方向的主应力影响程度并不是完全一致的。相交角度不同时,垂直应力可能表现为应力集中或应力降低,而水平应力只表现为应力降低;破碎带宽度不同时,垂直应力只表现为应力集中,而水平应力可能表现为应力集中或应力降低;破碎带强度越小对垂直应力的影响越大,而对水平应力的影响则呈线性关系;埋深较浅对垂直应力的影响较大,而随着埋深增加,埋深对水平应力的影响不变;关键层强度对垂直和水平方向应力的影响程度却极为相似。展开更多
基金supported by the National Key R&D Program of China (Grant No. 2022YFF0503700)the special funds of Hubei Luojia Laboratory (220100011)+1 种基金Chao Xiong is supported by the ISSI-BJ project, “the electromagnetic data validation and scientific application research based on CSES satellite”ISSI/ISSI-BJ project “Multi-Scale Magnetosphere–Ionosphere–Thermosphere Interaction”。
文摘In this study, we provide a detailed case study of the X-pattern of equatorial ionization anomaly(EIA) observed on the night of September 12, 2021 by the Global-scale Observations of the Limb and Disk(GOLD) mission. Unlike most previous studies about the X-pattern observed under the severely disturbed background ionosphere, this event is observed under geomagnetically quiet and low solar activity conditions. GOLD's continuous observations reveal that the X-pattern intensity evolves with local time, while its center's longitude remains constant. The total electron content(TEC) data derived from the ground-based Global Navigation Satellite System(GNSS) network aligns well with GOLD observations in capturing the formation of the X-pattern, extending coverage to areas beyond GOLD's observational reach. Additionally, the ESA's Swarm mission show that both sides of the X-pattern can coincide with the occurrence of small-scale equatorial plasma bubbles(EPBs). To further analyze the possible drivers of the X-pattern, observations from the Ionospheric Connection Explorer(ICON) satellite were used. It shows that the latitudinal expansion(or width) between the EIA crests in two hemispheres is proportional(or inversely proportional) to the upward(or downward) plasma drift velocity, which suggests that the zonal electric field should have a notable influence on the formation of EIA X-pattern. Further simulations using the SAMI2 model support this mechanism, as the X-pattern of EIA is successfully reproduced by setting the vertical plasma drift to different values at different longitudes.
文摘湖泊沉积物作为重要的环境演化记录载体,其矿物组合特征蕴含了丰富的古环境信息。然而,由于沉积物中晶质和非晶质组分的复杂共存关系,以及多相矿物体系的相互干扰效应,其精确定量分析一直是沉积学研究中的技术难点。该研究以西藏中部封闭咸水湖泊巴木错沉积物为研究对象,系统分析、评估了参比强度比(RIR)法和Rietveld全谱拟合法在复杂沉积物矿物定量分析中的可靠性和应用效果。文章采用高纯度刚玉作为内标物质,设计了1∶1、3∶7和1∶9三组不同配比的混合样品,通过X射线衍射(XRD)分析获取了完整的衍射数据。基于COD晶体结构数据库,分别采用RIR值法和Rietveld全谱拟合法进行定量计算,并结合非晶含量测定方法,构建了完整的矿物定量分析体系。研究结果表明,Rietveld全谱拟合法表现出优异的分析精度和稳定性:对于含量大于20%的主量相,相对标准偏差(RSD,Relative Standard Deviation)控制在3%以内;含量在5%~20%之间的次量相,RSD值保持在5%~10%范围内;即使对于含量低于5%的微量相,其定量结果也显著优于RIR值法。特别是在处理非均质样品时,Rietveld法表现出良好的适应性,各矿物相含量与混合比例呈现显著的线性相关性(R^(2)>0.95)。相比之下,RIR值法在高含量内标条件下(50%和30%)表现出显著的不稳定性,定量结果的相对偏差超出了SY/T5163-2018标准规定的允许范围。这种局限性主要源于其对单个衍射峰强度比值的过度依赖,易受样品基体效应和优势相干扰的影响。此外,通过非晶含量计算,获得了原始沉积物样品中约31%的非晶态物质含量,三组混合样品计算结果的高度一致性(RSD<3%)进一步验证了Rietveld法的可靠性。该研究不仅系统评估了两种定量方法的适用性,而且在复杂湖泊沉积物分析中首次实现了晶质矿物和非晶质组分的协同定量。研究结果对完善湖泊沉积物矿物定量分析方法,提高环境重建的准确性具有重要意义和应用价值。
文摘通过使用RFPA(Rock Failure Process Analysis System)二维模拟软件,分别研究了断层相交角度θ、破碎带宽度、关键层强度、破碎带强度、埋深5个参数对X型正断层交汇处垂直和水平方向应力场分布的影响。研究表明,这些因素在不同范围内,都对断层交汇处地应力场的分布有不同程度的影响,且这些因素对垂直和水平两个方向的主应力影响程度并不是完全一致的。相交角度不同时,垂直应力可能表现为应力集中或应力降低,而水平应力只表现为应力降低;破碎带宽度不同时,垂直应力只表现为应力集中,而水平应力可能表现为应力集中或应力降低;破碎带强度越小对垂直应力的影响越大,而对水平应力的影响则呈线性关系;埋深较浅对垂直应力的影响较大,而随着埋深增加,埋深对水平应力的影响不变;关键层强度对垂直和水平方向应力的影响程度却极为相似。
