Analyzing ice dynamics using Sentinel-1 data at the Solheimajoküll Glacier,Iceland

ABSTRACT

The climate in southern Iceland has warmed over the last 70 years, resulting in accelerated glacier dynamics at the Solheimajoküll glacier. In this study, we compare glacier terminus locations from 1973 to 2018, to changes in climate across the study area, and we derive ice-surface velocities (2015–2018) from satellite remote-sensing imagery (Sentinel-1) using the offset-tracking method. There have been two regional temperature trends in the study period: cooling (1973–1979) and warming (1980–2018). Our results indicate a time lag of about 20 years between the onset of glacier retreat (?53 m/year since 2000) and the inception of the warming period. Seasonally, the velocity time series suggest acceleration during the summer melt season since 2016, whereas glacier velocities during accumulation months were constant. The highest velocities were observed at high elevations where the ice-surface slope is the steepest. We tested several scenarios to assess the hydrological time response to glacier accelerations, with the highest correlations being found between one and 30 days after the velocity estimates. Monthly correlation analyses indicated inter-annual and intra-annual variability in the glacier dynamics. Additionally, we investigate the linkage between glacier velocities and meltwater outflow parameters as they provide useful information about internal processes in the glacier. Velocity estimates positively correlate with water level and negatively correlate with water conductivity between April and August. There is also a disruption in the correlation trend between water conductivity and ice velocity in June, potentially due to a seasonal release of geothermal water.     

康古尔塔格硅灰石矿床地质特征与成矿条件分析

作者首次在该区找到了硅灰石矿。在专题研究基础上，分析了区域地层、构造、岩浆活动和硅灰石矿床地质特征等，提出该硅灰石矿主要产于康古尔断裂带内的花岗岩与碳酸盐地层接触带，属矽卡岩型硅灰石矿。对区内花岗岩、碳酸盐地层、矽卡岩、大地构造等硅灰石成矿条件作了分析，初步提出了该矿主要应用领域为建筑陶瓷工业。     

Conditioning mean steady state flow on hydraulic head and conductivity through geostatistical inversion

Nonlocal moment equations allow one to render deterministically optimum predictions of flow in randomly heterogeneous media and to assess predictive uncertainty conditional on measured values of medium properties. We present a geostatistical inverse algorithm for steady-state flow that makes it possible to further condition such predictions and assessments on measured values of hydraulic head (and/or flux). Our algorithm is based on recursive finite-element approximations of exact first and second conditional moment equations. Hydraulic conductivity is parameterized via universal kriging based on unknown values at pilot points and (optionally) measured values at other discrete locations. Optimum unbiased inverse estimates of natural log hydraulic conductivity, head and flux are obtained by minimizing a residual criterion using the Levenberg-Marquardt algorithm. We illustrate the method for superimposed mean uniform and convergent flows in a bounded two-dimensional domain. Our examples illustrate how conductivity and head data act separately or jointly to reduce parameter estimation errors and model predictive uncertainty.This work is supported in part by NSF/ITR Grant EAR-0110289. The first author was additionally supported by scholarships from CONACYT and Instituto de Investigaciones Electricas of Mexico. Additional support was provided by the European Commission under Contract EVK1-CT-1999-00041 (W-SAHaRA-Stochastic Analysis of Well Head Protection and Risk Assessment).     

Remote structural health monitoring with serially multiplexed fiber optic acoustic emission sensors

Development and testing of a serially multiplexed fiber optic sensor system is described. The sensor differs from conventional fiber optic acoustic systems, as it is capable of sensing AE emissions at several points along the length of a single fiber. Multiplexing provides for single channel detection of cracks and their locations in large structural systems. An algorithm was developed for signal recognition and tagging of the AE waveforms for detection of crack locations. Laboratory experiments on plain concrete beams and post-tensioned FRP tendons were performed to evaluate the crack detection capability of the sensor system. The acoustic emission sensor was able to detect initiation, growth and location of the cracks in concrete as well as in the FRP tendons. The AE system is potentially suitable for applications involving health monitoring of structures following an earthquake Supported by: National Science Foundation, Grant number CMS-9900338     

Modeling Biogeochemistry,the Key for Understanding Environmental Chemistry of a Semi－Arid Soil in Egypt

1IntroductionThecomponentsoftheenvironmentaredamagedbyagriculturalpractices.Soilslosstheirfer tilityandwaterdeterioratesduetopollution .Chemicalweatheringofmineralandsoiloccursattheinterfacesbetweentheliquidandsolidphases;consequentlythesurfaceareaandcompositionofthemineralsplayanimportantroleinthisprocess.GarrelsandMackenzie ( 1 96 7)suggestedthatincon gruentweatheringreactionswouldproducedissolvedspeciesandnewsolidsthataremorestableintheweatheringenvironmentthantheoriginalbedrockminerals.Ro…     

RADARSATSNBSAR数据在大面积水稻估产中的应用研究

由于雷达遥感的全天候、全天时的优势,使之成为南方大范围农业信息动态监测的最佳遥感手段。为了适宜于运行系统,本研究采用加拿大雷达卫星（RADARSAT）窄波扫描模式（SNB）数据,以广东省为例进行了大范围水稻估产。通过建立稻作图谱,解决了在地形复杂、农业集约化程度低、水稻田分布不规则,且地块间田间管理水平差异很大等诸多因素影响下的水稻信息提取问题;在野外观测站采集的水稻生长期生理生态数据的基础上,建立了基于RADARSAT SNB SAR的雷达遥感时序信息水稻估产模型。通过2000年早、晚两季水稻估产的实践证明,此模型估产的精度在平原区达到95％,而在复杂的丘岭谷地则需进一步提高图像预处理的精度,改进特殊地段估产模型的精度。从实用性而言,这是一套高效、经济的技术方法,易于投入实际运行阶段。     

长江三峡库区(奉节-巴东段)移民工程遥感动态监测

在长江三峡库区移民工程中 ,我们采用 ETM+、SPOT、IKONOS等多源、多时相、多分辨率航天、航空遥感数据组合 ,监测移民工程的动态变化 ,通过对库区奉节 -巴东段移民搬迁建与安置、新开发用地分布、土地利用与土地结构变化、地质灾害及衍生地质灾害与防治、库区环境及生态平衡与改善经济结构以及移民工程遥感动态监测等 ,取得突破性进展 ,获取了一批重要成果。为三峡移民工程进一步全面、安全地实施、改进规划管理工作及库区经济可持续发展 ,提供了科学依据和决策性建议。     

延河流域生态环境动态监测系统与应用

以遥感 (RS)、地理信息系统 (GIS)、全球定位系统 (GPS)为核心技术 ,采用 ETM/ TM卫星数据、航空机载对地观测数据 ,结合地面测试和综合调查方法 ,完成了延河流域面积 10 0 15 .797km₂的生态环境本底调查 ,建立了 1990～2 0 0 0年的生态环境动态监测系统。查明了区内主要物种和植被分布 ,土地利用 /土地覆盖现状及其动态变化 ,划分出 5个生态区 ,2 5个生态系统 ,提出了延河流域生态建设.     

福建省地震重点监视防御区城市防震减灾体系工程简介

福建省地震重点视防御区城市防震减灾体系工程以中国地震局关于建立健全地震监测预报、震灾预防和紧急救援三大体系为主要目标 ,以国家和福建省确定的地震重点监视防御区为主要目标区 ,尤以切实加强重点监视防御内城市的防震减灾措施 ,强化城市对地震灾害的综合防御能力为主要建设内容。该项目得到中国地震局、福建省委、省政府和有关地市大力支持 ,已列为福建省“十五”重点项目 ,省委、省政府为民办实事重点项目     

山西义兴寨金矿床金矿物颗粒的产出及其成矿动力学意义

山西义兴寨金矿床的金主要呈包体金和裂隙金两种产出状态.文章根据成矿地球化学动力学理论,论证了金元素在含矿断裂发生脆性破裂和脆-韧性扩张活动中析出的化学反应类型,以及受反应动力学条件的制约,形成矿石中金不同产出状态的规律.指出热液矿床中普遍存在的包体金为热液成矿早期阶段断裂发生脆性破裂和成矿流体沸腾,导致快速反应结晶的产物;而裂隙金和晶隙金为成矿晚期金等矿质在流体中残余富集,同时成矿断裂再次发生脉动破裂,即成矿热力学演化与有利的构造动力学因素耦合作用的结果.得出金矿物颗粒的产出状态具有成矿动力学意义的结论.