Value-Added Products Derived from 15 Years of High-Quality Surface Solar Radiation Measurements at Xianghe,a Suburban Site in the North China Plain

Surface solar radiation(SSR) is a key component of the energy budget of the Earth’s surface, and it varies at different spatial and temporal scales. Considerable knowledge of how and why SSR varies is crucial to a better understanding of climate change, which surely requires long-term measurements of high quality. The objective of this study is to introduce a value-added SSR dataset from Oct 2004 to Oct 2019 based on measurements taken at Xianghe, a suburban site in the North China Plain; two va...     

多源空间信息数据库数据更新技术研究

从多级空间信息数据库的数据来源和数据内容着手,对建设过程中的业务数据空间化方法、数据的存储与组织模式、数据的更新机制进行深入探讨,为多级空间信息数据库建设提供理论和实际应用参考.     

基于Web文本的灾害事件信息获取进展

大数据时代海量网络文本中蕴含的灾害事件信息是防灾减灾研究和应用的重要资源。从异构的Web文本中快速、准确抽取灾害事件时空信息和属性信息,分析其时空动态变化模式与趋势并进行可视化表达,是当前地理信息与灾害信息领域关注的热点。本文从Web文本挖掘的整体技术框架、灾害主题页面抓取、灾害事件信息解析与抽取、灾害事件信息空间展示分析、以及防灾减灾应用系统等方面调研和综述了相关进展。针对防灾减灾领域的Web文本信息获取未来趋势,分析概括了全流程的Web文本灾害事件信息提取适用技术,并指出未来研究趋势：① 重点开展全球灾害信息全景式获取分析,实现全球灾害事件信息的自动化获取、分析及可视化展示;② 向联合国可持续发展目标（SDGs）和中国“一带一路”倡议,加强典型热点区域的Web灾害事件信息获取分析应用研究并形成示范系统;③ 按照数据、信息、知识的应用层次,建立以大数据挖掘和分析技术支撑的新型防灾减灾知识服务系统。     

Optimization of UAVs-SfM data collection in aeolian landform morphodynamics: a case study from the Gonghe Basin,China

UAVs-SfM (unmanned aerial vehicles-structure-from-motion) systems can generate high-resolution three-dimensional (3D) topographic models of aeolian landforms. To explore the optimization of UAVs-SfM for use in aeolian landform morphodynamics, this study tested flight parameters for two contrasting aeolian landform areas (free dune and blowout) to assess the 3D reconstruction accuracy of the UAV survey compared with field point measurements using differential RTK-GPS (real-time kinematic-global positioning system). The results reveal the optimum UAVs-SfM flight set-up at the free-dune site was: flying height = 74 m, camera tilt angle = −90°, photograph overlap ratio = 85%/70% (heading/sideways). The horizontal/vertical location error was around 0.028–0.055 m and 0.053–0.069 m, respectively, and a point cloud density of 463/m³ was found to generate a clear texture using these flying parameters. For the < 20 m deep blowout the optimum set-up with highest accuracy and the lowest cliff texture distortion was: flying height = 74 m combined camera tilt angle = −90° and −60°, photograph overlap ratio = 85%/70% (heading/sideways), and an evenly distributed GCPs (ground control points) density of 42/km² using these flying parameters. When the depth of the blowouts exceeded 40 m, the optimum flight/survey parameters changed slightly to account for more challenging cliff texture generation: flying height = 80 m (with −90° and −60°combined camera tilt angle), GCPs density = 63/km² to generate horizontal and vertical location error of 0.024 m and 0.050 m, respectively, and point cloud density of 2597.11/m³. The main external factors that affect the successful 3D reconstruction of aeolian landforms using UAVs-SfM are the weather conditions, manipulation errors, and instrument system errors. The UAVs-SfM topographic monitoring results demonstrate that UAVs provide a viable and robust means for aeolian landform morphodynamics monitoring. Importantly, the rapid and high precision 3D reconstruction processes were significantly advanced using the optimal flight parameters reported here. © 2020 John Wiley & Sons, Ltd.     

A new energy density calculation method for reservoir delineation using seismic low-frequency signal

In comparison to high-frequency signals, low-frequency seismic signals suffer less from scattering and intrinsic attenuation during wave propagation, penetrate deeper strata and thus can provide more energy information related to the hydrocarbon reservoirs. Based on the asymptotic representation for the frequency-dependent reflections in the fluid-saturated pore-elastic media, we first derive a novel equation of the reservoir energy density and present an efficient workflow to calculate the reservoir energy density using low-frequency seismic data. Then, within a low-frequency range (from 1 to 30 Hz), we construct an objective function to determine the optimal frequency, using the energy densities calculated from the post-stack seismic traces close to the wells. Next, we can calculate the reservoir energy density using the instantaneous spectra of optimal frequency at the low-frequency end of the seismic spectrum. Tests on examples for synthetic and field data demonstrate that the proposed reservoir energy density can produce high-quality images for the fluid-saturated reservoirs, and it produces less background artefacts caused by elastic layers. This method provides a new way to detect the location of hydrocarbon reservoirs and characterize their spatial distribution.     

绿色宝石之王——祖母绿

介绍祖母绿宝石的物理化学特征,矿床成因类型及主要产地,并叙述祖母绿的鉴别及质量评价依据。     

平武地电观测实验

对平武地区自2009年7月以来开展的地电观测实验进行了总结,将地电实验的原理方法和实验改进过程作了详细的阐述,同时也将取得的观测数据进行了系统地分析和处理。实验发现,本地区地下水中的微电流观测数据变化与附近龙门山断裂带及周边地区中强地震活动存在较为密切的相关性,并探讨了观测实验中存在的问题,提出了改进的方法和建议。期望通过该实验,将这种地电前兆观测方法运用于本监视区及周边地区地震活动的监测和为预报实践打下基础。     

干旱区内陆河流域中游地区全新世沉积相变与环境变化——以石羊河流域为例

中国干旱区内陆河流域中游地区分布了大量晚第四纪河、湖相交替的沉积地层,这些沉积物被广泛用于古气候和古环境重建。然而,以往的研究较多关注沉积物的理、化、生指标,而忽略了沉积相变的古环境意义,这可能使古环境重建结果产生偏差。针对这一问题,选取干旱区典型内陆河——石羊河中游地区的JDT全新世沉积剖面,进行年代学、沉积相、岩性和粒度的研究,并与该区域已有的HSH全新世剖面的地球化学和古生物指标进行对比,在分析沉积相的基础上讨论二者的环境代用指标,重建石羊河中游地区全新世的古环境。两个剖面在年代和岩性上具有很好的一致性,指示了石羊河中游地区约8500 cal yr BP-3000 cal yr BP以来的沉积过程。两剖面从底部到上部可分为六层：河流相沉积（F层）——河湖相沉积（E层）——湖相沉积（D层）——浅湖—风成沉积（C层）——风成沉积（B层）——风成沉积（A层）,代表了不同沉积相及其转换过程。综合讨论沉积物岩性、沉积相和各种古环境代用指标认为：石羊河中游地区的沉积相体现了从河流相到湖相再到风成沉积物的变化过程,指示了全新世的干旱化过程。这与以往研究中认为石羊河流域全新世气候变化具有波动性的观点存在一定差异。因此,在研究沉积相变化的基础之上讨论沉积物的物理、化学和生物指标的含义,而非简单地研究这些指标的数值,是干旱区流域性气候变化对比研究的新视角。     

Holocene climate cycles in northwest margin of Asian monsoon

In the mid-latitude regions of the Asian continent,Zhuye Lake is located in the northwest margin of the Asian monsoon,where the modern climate is affected by the Asian monsoon and Westerlies.In this study,we investigated the absolutely dated Holocene records in Zhuye Lake for detecting the Holocene climate cycles.Totally,14 14 C dates and 6 optically simulated luminescence(OSL) dates are obtained from the QTH01 and QTH02 sections.The proxies of grain-size,total organic carbon content(TOC),C/N and δ 13 C are used for wavelet analysis,and the results show obvious ~256,~512 and ~1024-year climate cycles,which are consistent with the Holocene millennial and centennial scale climate cycles in the typical Asian summer monsoon domain.In different parts of the Zhuye Lake,the Holocene sediments show variable climate cycles that are affected by the lake basin topography.In the Zhuye Lake,the Holocene climate cycles are mainly correlated with the solar-related Asian summer monsoon variability and the North Atlantic ice-rafting events.