检索结果-南通市图书馆

Analysis of Landsat 8 detection of the interannual variability of grassland curing in Greater Melbourne,Australia

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Digital earth 2020年第11期13卷 1321-1338页

作者： Sike Li school of earth Atmosphere and EnvironmentFaculty of ScienceMonash UniversityMelbourneAustralia

As one of the main components of Grassland Fire Danger Index,grassland curing degree provides crucial information for determining grassland fire *** estimates of grassland curing are critical for determining grassland fire *** research focuses on the use of Landsat 8 to estimate grassland *** demonstrate that Landsat 8 observations can be used to estimate curing percentages as assessed by visual and ground sampling *** interannual variability for the Greater Melbourne region using Landsat 8 imagery from 2013 to 2019 is *** differences in curing times and degree are observed for sample sites surrounding Greater Melbourne due to climatic differences across the *** is regarded as an essential variable affecting curing degree and this relationship is evident for all five sample *** 8 curing results are compared to both visual observations and destructive sampling,the most accurate method,for accuracy *** 95%confidence level,Landsat 8 estimations are no different from destructive ground sampling ***,this study validates the use of Landsat 8 data as an effective and accurate way for grassland curing monitoring.

关键词： Grassland curing remote sensing grassland fires Melbourne interannual variability

Inter-satellite variability of grassland curing maps produced by different satellite sensors-Victoria,Australia

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Digital earth 2021年第7期14卷 899-920页

作者： Sike Li school of earth Atmosphere and EnvironmentFaculty of ScienceMonash UniversityClaytonAustralia

Grassland fires are a serious problem in Victoria,Australia due to large quantity of dry *** curing degree(GCD)measures the dryness of the grass and is an important factor for assessing grassland fire *** curing maps(GCMs)display the spatial distribution of GCDs,but the quality of GCMs varies depending on the spatial resolution of the observing satellite remote sensing *** higher the spatial resolution,the finer the GCD details and more spatial variations the GCM can *** this study,GCD calculation algorithm named MapVictoria based on MODIS data is tested for Landsat 8 Sentinel 2;GCMs generated from these three satellites are contrasted by their GCD differences,defined here as inter-satellite variability(ISV).ISV is used to identify areas where higher resolution satellite GCMs should be *** show that spatial resolution difference(ΔSR),seasonality and geographical locations affect the magnitude of the *** on these findings,this paper provides recommendations to decision makers on where and when to use which satellite for grassland observations.

关键词： Grassland curing remote sensing grassland fires Australia variability

Mechanism and kinetics of hydrothermal replacement of magnetite by hematite

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2019年第1期10卷 29-41页

作者： Jing Zhao Joel Brugger Allan Pring Chemical and Physical Science College of Science and Engineering Flinders University school of earth Atmosphere and the Environment Monash University

The replacement of magnetite by hematite was studied through a series of experiments under mild hydrothermal conditions(140 -220℃, vapour saturated pressures) to quantify the kinetics of the transformation and the relative effects of redox and non-redox processes on the transformation. The results indicate that oxygen is not an essential factor in the replacement reaction of magnetite by hematite, but the addition of excess oxidant does trigger the oxidation reaction, and increases the kinetics of the transformation. However, even under high O_2(aq) environments, some of the replacement still occurred via Fe^(2+) leaching from magnetite. The kinetics of the replacement reaction depends upon temperature and solution parameters such as pH and the concentrations of ligands, all of which are factors that control the solubility of magnetite and affect the transport of Fe^(2+) (and the oxidant) to and from the reaction front. Reaction rates are fast at ~200℃, and in nature transport properties of Fe and,in the case of the redox-controlled replacement, the oxidant will be the rate-limiting control on the reaction progress. Using an Avrami treatment of the kinetic data and the Arrhenius equation, the activation energy for the transformation under non-redox conditions was calculated to be 26 ± 6 kJ mol^(-1).This value is in agreement with the reported activation energy for the dissolution of magnetite, which is the rate-limiting process for the transformation under non-redox conditions.

关键词： Mineral replacement reaction Hematite Magnetite Kinetics Non-redox Redox

Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2015年第1期6卷 49-59页

作者： Peter G.Betts Louis Moresi Meghan S.Miller David Willis school of earth Atmosphere and EnvironmentMonash UniversityClayton Campus school of Mathematical Sciences Monash UniversityClayton Campus Department of earth Sciences University of Melbourne Department of earth Sciences University of Southern California

We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in： contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes fiat subduction above the plume, resulting in a ＂bowed＂ shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau ~ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the over- riding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen （Altiads）, which ar

关键词： Subduction Accretion Plateau Plume Central Asian Orogen Geodynamics

Rates of generation and growth of the continental crust

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2019年第1期10卷 165-173页

作者： Chris Hawkesworth Peter A.Cawood Bruno Dhuime school of earth Sciences University of Bristol school of earth Atmosphere and Environment Monash University CNRS-UMR 5243 Géosciences Montpellier Université de Montpellier

Models for when and how the continental crust was formed are constrained by estimates in the rates o crustal growth. The record of events preserved in the continental crust is heterogeneous in time with distinctive peaks and troughs of ages for igneous crystallisation, metamorphism, continental margin and mineralisation. For the most part these are global signatures, and the peaks of ages tend to b associated with periods of increased reworking of pre-existing crust, reflected in the Hf isotope ratios o zircons and their elevated oxygen isotope ratios. Increased crustal reworking is attributed to periods o crustal thickening associated with compressional tectonics and the development of supercontinents Magma types similar to those from recent within-plate and subduction related settings appear to hav been generated in different areas at broadly similar times before ~3.0 Ga. It can be difficult to put th results of such detailed case studies into a more global context, but one approach is to consider when plate tectonics became the dominant mechanism involved in the generation of juvenile continental crust The development of crustal growth models for the continental crust are discussed, and a number o models based on different data sets indicate that 65%-70% of the present volume of the continental crus was generated by 3 Ga. Such estimates may represent minimum values, but since ~3 Ga there has been reduction in the rates of growth of the continental crust. This reduction is linked to an increase in th rates at which continental crust is recycled back into the mantle, and not to a reduction in the rates a which continental crust was generated. Plate tectonics results in both the generation of new crust and it destruction along destructive plate margins. Thus, the reduction in the rate of continental crustal growth at ~3 Ga is taken to reflect the period in which plate tectonics became the dominant mechanism b which new continental crust was generated.

关键词： Continental crust growth curves Rates of crustal growth Tectonics

3D tomographic analysis of equatorial plasma bubble using GNSS-TEC data from Indonesian GNSS Network

在线全文

学校读者我要写书评

暂无评论

earth and Planetary Physics 2025年第1期9卷 127-136页

作者： Ihsan Naufal Muafiry Prayitno Abadi Teguh N.Pratama Dyah R.Martiningrum Sri Ekawati Yuandhika GWismaya Febrylian FChabibi Gatot HPramono Research Center for Climate and atmosphere Indonesian National Research and Innovation Agency(BRIN)BandungIndonesia Indonesian Geospatial Information Agency(BIG) JakartaIndonesia Dept.of Physics Faculty of ScienceUniversiti Teknologi MalaysiaJohor BahruMalaysia Dept.earth Planet Sci. Hokkaido UniversitySapporoJapan school of Electrical Engineering Telkom UniversityBandungIndonesia

Equatorial Plasma Bubbles(EPBs)are ionospheric irregularities that take place near the magnetic *** most commonly occur after sunset during the equinox months,although they can also be observed during other *** phenomenon significantly disrupts radio wave signals essential to communication and navigation *** national network of Global Navigation Satellite System(GNSS)receivers in Indonesia(>30°longitudinal range)provides an opportunity for detailed EPB *** explore this,we conducted preliminary 3D tomography of total electron content(TEC)data captured by GNSS receivers following a geomagnetic storm on December 3,2023,when at least four EPB clusters occurred in the Southeast Asian *** and extracted TEC depletion with a 120-minute running average were then used as inputs for a 3D tomography *** 2D spatial distribution consistently captured the four EPB clusters over *** tomography results were validated through a classical checkerboard test and comparisons with other ionospheric data sources,such as the Global Ionospheric Map(GIM)and International Reference Ionosphere(IRI)*** of the results demonstrates the capability of the Indonesian GNSS network to measure peak ionospheric *** findings highlight the potential for future three-dimensional research of plasma bubbles in low-latitude regions using existing GNSS networks,with extensive longitudinal coverage.

关键词： EPB Indonesian GNSS Network 3D tomography

Geochronology and geochemistry of the Donglufang porphyry-skarn Mo-Cu deposit in the southern Yidun Terrane and their geological significances

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2018年第5期9卷 1433-1450页

作者： Wenyan He Shixiong Xie Xudong Liu Xue Gao Yanlu Xing State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences school of earth Atmosphere and Environment Monash University

The newly-discovered Donglufang Moe Cu porphyry-skarn deposit is located in the southern Yidun Terrane, southeast Tibet, with more than 80 million tonnes(Mt) of reserves(grading 0.15 wt.% Mo and0.48 wt.% Cu) hosted in Triassic strata and Late Cretaceous granodiorite porphyry. Ree Os dating of molybdenum ore yielded a weighted mean age of 84.9 ± 1.0 Ma and an isochron age of 85.2 ± 0.6 ***-ICP-MS Ue Pb dating of zircons from the granodiorite porphyry yielded206 Pb/238 U ages ranging from 87.4 Ma to 84.2 Ma with a weighted mean206 Pb/238 U age of 85.1 ±0.5 Ma, indicating a temporal linkage between granitic magmatism and Moe Cu mineralization. Geochemical analyses show that the granodiorite porphyries are I-type granites with Si O_2 contents of 64.3 -66.7 wt.%. These rocks are typically metaluminous with high K_2 O/Na_2 O ratios, low Mg O(1.32 -1.56 wt.%), Cr(5.6 -12.9 ppm), Ni(3.79 -10.81 ppm), Mg#(43 -52) values, and high Sr(304 -844 ppm), Sr/Y(21.2 -50.8) and La/Yb ratios(37.0 -60.1). They are enriched in light rare-earth elements(LREE) relative to heavy rare-earth elements(HREE), with slightly negative Eu anomalies, and are enriched in Th, U and large ion lithophile elements(LILE, e.g., K and Rb), and depleted in high field strength elements(HFSE, e.g., Nb, Ta, P and Ti). They also show negative zircon εHf(t) values(-6.7 to -2.3) and negative whole rock εNd(t) values(à5.2 to-4.3), as well as old Hfe Nd model ages, indicating the magmas were derived from a thickened ancient lower crust within the garneteamphibolite facies. Considering the tectonic evolution of the Yidun Terrane, geochemical characteristics of granodiorite porphyry, and the ages of mineralization obtained in this study. We suggest that the Donglufang deposit was formed in a post-collisional setting, which has a genetic relationship with the emplacement of the granodiorite porphyry. The present study provide key information for the exploration of the Late Cretaceous metallogeny in the Yidun Terrane.

关键词： Late cretaceous Mo-Cu metallogenesis Molybdenite Re-Os geochronology U-Pb zircon dating Yidun terrane

Comparative analysis of empirical and deep learning models for ionospheric sporadic E layer prediction

在线全文

学校读者我要写书评

暂无评论

earth and Planetary Physics 2025年第1期9卷 10-19页

作者： BingKun Yu PengHao Tian XiangHui Xue Christopher JScott HaiLun Ye JianFei Wu Wen Yi TingDi Chen XianKang Dou Institute of Deep Space Sciences Deep Space Exploration LaboratoryHefei 230088China CAS Key Laboratory of Geospace environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China Department of Meteorology University of ReadingReading RG66BBUK

Sporadic E(Es)layers in the ionosphere are characterized by intense plasma irregularities in the E region at altitudes of 90-130 *** they can significantly influence radio communications and navigation systems,accurate forecasting of Es layers is crucial for ensuring the precision and dependability of navigation satellite *** this study,we present Es predictions made by an empirical model and by a deep learning model,and analyze their differences comprehensively by comparing the model predictions to satellite RO measurements and ground-based ionosonde *** deep learning model exhibited significantly better performance,as indicated by its high coefficient of correlation(r=0.87)with RO observations and predictions,than did the empirical model(r=0.53).This study highlights the importance of integrating artificial intelligence technology into ionosphere modelling generally,and into predicting Es layer occurrences and characteristics,in particular.

关键词： ionospheric sporadic E layer radio occultation ionosondes numerical model deep learning model artificial intelligence

High Spatial Resolution Mapping of Dykes Using Unmanned Aerial Vehicle(UAV) Photogrammetry: New Insights On Emplacement Processes

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2016年第S1期90卷 52-53页

作者： Alexander CRUDEN Stefan VOLLGGER Greg DERING Steven MICKLETHWAITE school of earth Atmosphere and Environment Monash University school of earth Sciences University of Western Australia

Remote sensing has played a pivotal role in our understanding of the geometry of dykes and dyke swarms on earth,Venus and Mars(West and Ernst,1991;Mege and Masson,1995;Ernst et al.,2005).Since the 1970’s

关键词： Photogrammetry High Spatial Resolution Mapping of Dykes Using Unmanned Aerial Vehicle New Insights On Emplacement Processes UAV