Inter-comparison of Aermod and ISC3 modeling results to the Alaska tracer field experiment

AERMOD is an advanced plume model that incorporates updated treatments of the boundary layer theory, understanding of turbulence and dispersion, and includes handling of terrain interactions as well as the PRIME downwash algorithm. It was reported that the US EPA approved AERMOD for short-range dispersion modeling. It was the high time that AERMOD would replace ISC3. ISC3 is a traditional Gaussian plume model regarded as the regulatory model of US EPA with the capacity of building downwash similar to that of AERMOD. In this paper, the authors describe the advantages of AERMOD over the regulatory model of ISC3 by comparing their predicted ground level concentrations (GLC) along downwind distance to the Alaska tracer field data. The field experiment features buoyant release of effluent at elevated height over a flat terrain and local flows influenced by building downwash. Three measures to compare the observed and simulated concentration data, such as linear regression, quantile-quantile (QQ) and residual box are utilized. To sum up, AERMOD shows significantly better space-time correlation and probability distribution than the ISC3, which frequently overestimates the GLC for effluent released with significant plume rise under stable atmospheric conditions. The performance of AERMOD is greatly enhanced by introducing the state-of-the-art knowledge of boundary layer meteorology as well as the turbulence parameterization method. In particular, AERMOD takes into account the meander effect on coherent plume in stable condition with current state-of-the-art Planetary Boundary Layer (PBL) parameterizations, while ISC3 is not capable of producing such important effect. Generally speaking, 1.17 is the overall predicted-to-observed ratio for short-term averages using AERMOD. 1.94 is the overall predicted-to-observed ratio for short-term averages using ISC3.     

Geo3DML与GOCAD数据模型与转换研究

三维地质模型数据交换格式Geo3DML已在一定范围进行试用,其制定解决了我国目前三维地质模型数据格式繁多、交换困难的问题,极大地方便了三维地质模型数据的管理与共享。GOCAD是国际上公认的主流建模软件,在地质工程、地球物理勘探、矿业开发、水利工程中有广泛的应用,被众多石油公司和服务公司等用户广泛认可。通过对Geo3DML标准格式和GOCAD数据格式进行对比分析研究,实现了基于Geo3DML标准的三维地质模型数据与GOCAD三维地质模型数据的相互转换,对于进一步实现三维地质模型数据的共享和集成管理具有重要意义。     

三维地质模型构建方法的研究及应用

地质体三维建模是地学信息系统的核心问题之一.对三维GIS及地学领域的空间构模方法的现状进行分析,结合地质体工程特点,提出一种三维地学空间构模方法--似三棱柱(STP)法.该方法以似三棱柱体作为三维地质体建模的基本体元,并采用5类基本元素和6组拓扑关系对似三棱柱体的数据结构进行描述.它能有效地表达各种三维地质现象,也可以更好地与传统的多层TIN模型结合,维护好空间实体的拓扑关系.基于本文的建模方法开发了一个适合地质领域的三维GIS初步原型,并用实际钻孔数据进行了验证.     

中国岩石圈三维结构数据库总库管理系统

中国岩石圈三维结构数据库总库管理系统是中国岩石圈三维结构数据库的管理和服务中心。在中国岩石圈三维结构数据库需求分析基础上,完成了系统总体设计,制订各项技术标准;开发设计一个元数据编辑器和元数据浏览器;应用统一建模语言UML设计和优化了数据库结构;采用ESRI公司Geodatabase的数据模型,利用计算机辅助设计CASE工具设计中国岩石圈三维结构数据库。在ArcObjects和MapObjects的基础上,分别建立了功能齐全、操作简便的两套组件式总库管理系统,分别适合专业和非地理信息系统专业人员。     

基于MODIS数据的东北地区积雪覆盖率估算

东北地区是我国三大积雪区之一,森林覆盖面积占总面积的40%左右。受森林冠层的影响,当前的MODIS雪盖产品（V6）提供的积雪覆盖率标准模型对东北地区积雪覆盖率估算结果存在明显的低估现象。基于此,采用分区建模的方式：在森林地区,计算归一化差值林地积雪指数（NDFSI）,建立像元积雪覆盖率（FSC）与NDFSI及NDVI之间的线性关系;在非森林地区,采用MOD10A1 V6提供的归一化差值积雪指数（NDSI）,建立像元积雪覆盖率（FSC）与NDSI及NDVI之间的线性关系。采用Landsat 8 OLI数据提取的积雪覆盖率（FSC）对分区建模的估算结果与标准模型的估算结果进行对比,发现进行估算的过程中均方根误差和平均绝对误差这两项指标的数值相对于标准模型有了大幅下降,这一结果在林区有更显著的表现。计算得到的决定系数R²,在本文模型也有提高。以T1林区影像为例,本文模型的均方根误差和平均绝对误差分别为0.246、0.055,而标准模型的两项指标则分别为0.420、0.348。本文模型和标准模型的决定系数分别为0.675、0.641。     

3D seismic analysis of the Coast Shear Zone in SE Alaska and Western British Columbia: Broadside analysis of ACCRETE wide-angle data

The multidisciplinary ACCRETE project addresses the question of continental assemblage in southeast Alaska and western British Columbia by terrane accretion and magmatic addition. The previous studies of this project yielded important information for understanding the structures across the Coast Shear Zone (CSZ) and the formation of the CSZ and the Coast Mountains Batholith (CMB). The present study extends these interpretations into pseudo-3-D by using two additional wide-angle ACCRETE seismic lines. By analyzing the broadside wide-angle data using a series of laterally homogeneous 2-D models, we derive a lower-resolution 3-D velocity model of the outboard terranes and constrain variations in crustal thickness across and along the CSZ. Models of the broadside data confirms major structural and compositional trends extend along strike to the northwest. The key features are: a) a steep Moho ramp only  15-km wide is coincident with the CSZ and divides thin (25 ± 1 km) crust to the west below the west-vergent thrust belt (WTB) from thicker ( 31 ± 1 km) crust to the east below the CMB, (b) low-velocity mantle (7.7--7.9 km/s) extends beneath the entire study region indicating high crustal and upper-mantle temperatures below the WTB and CMB, and (c) the Alexander terrane is characterized by strong mid-crustal reflectivity and high lower crustal velocities that are consistent with gabbroic composition. This study extends the earlier interpretation and implies that the ramp is indeed likely associated with transpressional tectonics and magmatic crustal addition east of the CSZ.     

三维地层信息系统在岩土工程中应用研究

根据岩土介质中复杂的地质现象及其地层的层状展铺特性,建立了三维地层模型。三维地层信息系统在岩土工程中的重要作用就是数据库管理功能、复杂的地质现象的可视化及分析功能。阐述了3DSIS的功能和应用,提出了3DSIS与数值分析方法、专家系统耦合集成的模型。     

三维拓扑数据的生成算法与交互修改方法研究

在分析现有三维矢量拓扑关系的基础上,提出了三维矢量数据结构的要素拓扑模型（Feature Topological Mod—el,FTM）。FTM三维拓扑模型比传统三维模型的优势有3点：（1）直接引入三角形对象,更加有利于表示任意形状的三维体数据。（2）简化基本拓扑关系的定义,使用相对简单的三角形和边的拓扑关系,表达相对复杂的实体和曲线的拓扑关系;使用带拓扑关系的边的集合表示三维曲线,既表达了曲线对象,又不影响基本拓扑关系的维护。（3）使用实体之间的包含模型,解决环（洞）的拓扑关系。同时,使用FTM对三维离散三角形数据进行拓扑化处理,对其中存在的拓扑错误提出具体的解决方案。该拓扑模型成功应用于自主研发的三维勘查软件“探矿者”中。     

3D GIS Supporting Underground Urbanisation in the City of Turin (Italy)

This paper introduces a 3D geological and geotechnical model of the subsoil of the city of Turin managed by means of a Geographical Information System (GIS). The 3D GIS of the subsoil of Turin represents a useful decision-support tool in the underground management for engineering purposes and it’s here proposed as base geological elaborate to support future underground work in the city. In the final part of the paper, an application of the information coming from the 3D model is shown to define the characteristics of the optimal excavation machines (the type and disposition of tools on the head and the necessary engine power) for the future developments of the Underground Metro System.     

基于水平集的复杂三维地层模型建模及在地下工程中的应用研究

由于地质体存在断层、尖灭、出露等复杂地质现象,在三维地层建模时,为了表达这些现象,无论是面模型还是体模型或混合模型,都存在空间分割或曲面求交线的问题。由于地质体拓扑关系的复杂性、数据误差以及计算机精度问题,使得这些模型在实际建模过程中常常失效。运用水平集理论可以有效解决这一问题,水平集用隐函数表达曲面（或超曲面）,可以实现复杂地质体的表达及并、交、差等拓扑运算。在三维地层建模中,插值生成各种地质界面后,用水平集表达这些地质界面,利用水平理论完成各种复杂的拓扑操作,建立以水平集表达的三维地层模型。在此基础上,插入水平集表达的各种工程活动界面,利用水平集理论进行拓扑操作,可构建各种工程活动后的地层模型。再利用Marching cube算法抽取各种地质界面或工程活动界面,构建可用于实时可视化或用于工程评估（如有限元计算）等的NMTINF-BR地层模型或工程活动后的NMTINF-BR地层模型。     

四种南极数字高程模型的精度比较与分析

南极数字高程模型（DEM）是南极冰盖研究的基础数据,目前国际通用的全南极DEM数据主要有JLB97 DEM、RAMPv2 DEM、ICESat DEM以及Bamber 1km DEM. 利用DEM对DEM验证的方式对四种DEM的精度进行比较分析. 结果表明：Bamber 1km DEM和ICESat DEM之间的高程差异最小,平均高程差小于1.8 m,二者均有较高的可靠性. RAMPv2 DEM与Bamber 1km DEM的高程差大于1.9 m,在81.5° S以南和坡度较大的区域,高程差异更为明显,高程可靠性较低. JLB97 DEM与上述三种DEM的偏差超过10 m,高程可靠性最低.     

Hydrochemical models of the sulphidic tailings dumps at Matchless (Namibia) and Selebi-Phikwe (Botswana)

The sulphidic tailings dumps at Matchless (Namibia) and Selebi-Phikwe (Botswana) are located in a similar semiarid environment but have a contrasting mineralogical composition. The Matchless tailings are pyrite-rich, whereas the Selebi-Phikwe tailings are dominated by pyrrhotite. Hydrochemical models are established with computer codes for water-balance, sulphide oxidation rate and hydrochemical equilibrium calculations. The data input is based on detailed mineralogical, chemical and kinetic investigations carried out on the core of boreholes drilled in 2000 and 2003. The oxidation of pyrrhotite proceeds at a much faster rate than the oxidation of pyrite. The PYROX code, which is used for kinetic calculations, can take these differences into account by applying different oxide-coating diffusion coefficients (D₂) for pyrrhotite and pyrite. Humidity-cell testing is widely used to predict the post-mining composition of drainage water in humid climates. However, the semiarid conditions at Matchless and Selebi-Phikwe only allow a minimal water flux within the dump. Under such conditions, humidity-cell testing is likely to overestimate the seepage-water pH. This is suggested by the hydrochemical equilibrium calculations for the post-mining period at Selebi-Phikwe, which predict a seepage-water pH about one unit lower than the pH at the end of the 26-weeks humidity-cell testing period. The acidity of the seepage water can be reduced by about half a pH unit, if an oxygen barrier below the evaporation zone is installed. A clay layer 0.5 m thick covered by >1.5 m tailings represents the optimal design for a wet barrier. All three computer codes used for water-balance calculations (HELP3, UNSAT-H and HYDRUS-1D), predict >85% average water saturation for such a layer, which diminishes the diffusion of oxygen into the pile and production of SO₄⁻² and H⁺. The alternative design for a dry barrier consists of a vegetated silt layer 1 m thick on top of the tailings. This barrier does not significantly influence the diffusion of oxygen although it reduces the net infiltration to ≤11 mm/year.     

陇中黄土高原LAS在非均匀下垫面的观测优势及其在区域陆面模式验证中的初步应用

目前通用的通量观测技术涡动相关仪（EC）在区域陆面模式验证中存在能量不闭合和空间代表性有限的问题,寻求改进EC观测热通量的新技术是提高陆面模式验证效果的关键环节,大孔径闪烁仪（LAS）的出现有效改善了这一现状。基于黄土高原定西站2010年1月和6月的同步综合观测资料以及目前比较有代表性的陆面过程模式CLM的模拟数据,分析研究了LAS对EC观测地表能量不平衡问题的改进以及LAS对EC在区域陆面模式验证中的提高,结果表明：LAS可有效解决EC观测存在的地表能量不平衡问题,提高EC的地表能量闭合度,在非均匀下垫面LAS观测优势突出;利用LAS观测的感热通量进行区域陆面模式的验证,能够很大程度地避免EC能量不闭合和空间尺度不匹配在验证中造成的偏差,LAS观测更适合于大尺度模拟的验证,验证效果更好。     

A workflow for exploration sampling in regolith-dominated terranes using portable X-ray fluorescence: comparison with laboratory data and a case study

This paper presents and validates a workflow that provides for the rapid collection of reliable and robust portable X-ray fluorescence (pXRF) data in a regolith-dominated exploration setting. The analysis of regolith material by pXRF is challenging because of its variable Fe content (e.g. 0 to >70 wt%) that results in large matrix effects, which can be mitigated with appropriate standards. Here, we present a dataset from the Western Mount Isa Inlier, Queensland, Australia, comprising soil, lag, rock and rotary air blast (RAB) samples. In the soil dataset, comparison of the laboratory and pXRF datasets for Cu, Pb and Zn have R² > 0.9, and Cu and Zn fall within 2% of the laboratory data, while Pb is 77% less than the corresponding laboratory analyses. Iron, Al, K and Ca by pXRF perform reasonably well when compared with the laboratory data (R² = 0.59 for Al, R² > 0.9 for Fe, K and Ca, <25% variation from the laboratory data), while Mn, Rb and Sr have very good correlations (<8% variation) with R² > 0.94. Titanium, Zr, Ni, Cr and As have poorer comparisons. Overall, the RAB dataset shows similar trends with Cu overestimated by 17%, Zn underestimated by 4% and Pb overestimated by 69%; R² for all elements is >0.92. Since no suitable standards are available, the solid rock dataset was uncorrected; despite this limitation, the dataset shows good correlations with the laboratory data for many elements, and Cu is overestimated by 9.8% with an R² = 0.87. The poor analytical performance of Pb in all datasets is associated with erroneous Bi concentrations being reported by the pXRF unit. When high Fe and Pb amounts are present in a sample, erroneous Pb and Bi concentrations are reported, owing to a pile-up of the Fe K_α peak (6.405 keV) at ～12.8 keV, which is proximal to the Pb L_β (12.614 keV) and Bi L_β (13.023 keV) peaks. Despite the care that is required in validating data, by using pXRF there is substantial opportunity for dynamic exploration campaigns in regolith-dominated terranes with rapid turnaround times, additional elements that may not otherwise be analysed for and low analytical costs. Decisions to stop, continue or infill drill holes while the drill rig is present can be made in near-real time, and not after laboratory results are available and the drill rig has left the area.     

灰色系统和BP神经网络相结合的矿产资源预测模型

这里介绍了灰色系统和BP神经网络相结合的预测原理,利用BP网络,对改进的GM(1,1)残差修正模型所得预测的结果进行再预测的组合预测模型,并对攀枝花市钒钛磁铁矿的产量进行了预测。计算结果表明,该预测方法是可靠的,并具有较高的预测精度。     

3-D numerical models of viscous flow applied to fold nappes and the Rawil depression in the Helvetic nappe system (western Switzerland)

The Helvetic nappe system exhibits three-dimensional (3-D) features such as the lateral variation in geometry between the Morcles and Doldenhorn fold nappes or the Rawil depression. We perform 3-D finite element simulations of linear and power-law viscous flow to investigate fold nappe formation during shortening of a half graben with laterally varying thickness. 3-D ellipsoids and corresponding 2-D intersection ellipses are used to quantify finite strain. Fold nappes which formed above a thicker graben have (i) larger amplitudes, (ii) a less sheared and thinned overturned limb, and (iii) a larger thickness than fold nappes formed above a thinner graben. These results agree with observations for the Morcles and Doldenhorn nappes. We also perform 3-D simulations for a tectonic scenario suggested for the evolution of the Rawil depression. The basement is shortened and extended laterally and includes a graben which is oblique to the shortening direction and acts as mechanical weak zone. The graben causes laterally varying basement uplift generating a depression whose amplitude depends on the graben orientation and the stress exponent of basement and sediments. The axial plunge of the depression is smaller (approximately 10°) than the observed plunge (approximately 30°) indicating that additional processes are required to explain the geometry of the Rawil depression.     

1901~1950年5~9月北半球CRU数据与树轮资料的对比

气候变化的研究依赖于可靠的气候数据。英国东英吉利大学气候研究中心推出的一套依据观测资料插值所得的月平均气候数据集（CRU）,是目前使用较为广泛、质量较高的气候数据集。气候观测数据大多始于1950年,已有的研究也表明CRU数据在1950年后更具参考价值,但该数据集在1950年之前的可靠性不清楚。由于1950年之前缺乏器测数据,本研究使用树轮资料,对比每十年树轮重建温度（降水）与树轮附近CRU格点上的温度（降水）的距平和趋势的同号率,来评价CRU温度（降水）数据在不同地区的数据质量（可靠性）,由此发现从1930年代开始,CRU温度数据在欧洲和中西伯利亚可信度较高;从1940年代开始,CRU温度数据在美国东部可信度较高;从1940年代开始,CRU降水数据在美国东部与西西伯利亚可信度较高。研究发现,气象站密度对CRU数据质量有很大影响;在气象站密度小的地区,CRU温度或降水数据与树轮序列的差异更为显著,气候数据质量偏低;而数据可信度较高的年代和地区,气象站密度往往较大。

     

3D urban models: Recent developments in the digital modelling of urban environments in three-dimensions

This paper reports on recent developments in the visualisation of urban landscapes. There is a growing interest in the contstruction of 3D models of urban and built environment for which a host of digital mapping and rendering techniques are being developed. This paper extracts some of the cases that we came across during worldwide interviews carried out in March 2000. Building on this review, we identify the range of data and techniques adopted for the development of 3D contents and how they could contribute to geographical analysis and planning of urban environment. A particular focus is given on the effectiveness of GIS and its related methods for their capacity to accommodate the demands for visual representation of urban environment as well as the basis for analysis and simulation. This revised version was published online in July 2006 with corrections to the Cover Date.     

东海冷涡中心位置及季节性变化的初步研究

使用1958—2001年SODA温度场资料,较为系统地对东海冷涡附近海域具代表性剖面温度场进行逐月分析,对冷涡中心提取方法进行了总结完善。结果表明,35 m深处冷涡44年的平均中心位于(32.0°N,125.7°E);冷涡的中心位置存在较显著的季节性变化:经向变化方面,由夏季、秋季至冬季,冷涡中心位置自北向南逐渐移动;从冬季、春季至夏季自南向北移动。纬向变化方面,冬季冷涡中心明显偏西,其他季节冷涡中心偏东且中心经度变化不大。以上变化主要是由冷涡周边流场的季节性变化引起的。冷涡中心在冬末春初和秋初表现不明显,这应是由环流场季节性转换导致。