ASTER数据在浅覆盖区蚀变遥感异常信息提取中的应用——以新疆西准噶尔包古图斑岩铜矿岩体为例

遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER（Advanced Spaceborne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计）数据,因涵盖波长范围宽［VNIR（Visible and Near Infrared）、SWIR（Short wavelength Infrared）、TIR（Thermal Infrared）］、波段多（14个波段）、性价比合理等因素,ASTER数据的研究迅速发展。长久以来,对覆盖区进行蚀变遥感异常信息提取一直是遥感找矿的关注点之一。笔者等利用ASTER数据对浅覆盖区——包古图斑岩铜矿的Ⅱ号、Ⅴ号斑岩体进行蚀变遥感异常提取,提取的蚀变异常与野外地质情况吻合性好。分别提取了光谱特征谱带差异明显的2组蚀变矿物的异常信息：第一组是蒙脱石、埃洛石、伊利石与绢云母;第二组是方解石、黑云母与绿泥石。提出了需要进一步工作的异常靶区。     

AREMS/973模式系统对2004年中国汛期降水实时预报检验

2004年夏季5～8月，AREMS/973模式系统投入了业务运行，模式区域主要覆盖了中国大陆及周边临近地区，该模式系统基于中国气象局MICAPS/9210业务数据平台，每天2次、完全自动的实时预报24 h累积降水。作者主要对每日0000 UTC时起报的24 h累积降水预报场进行综合检验，由此对AREMS/973模式系统的24 h降水预报能力给予客观的评价。AREMS/973模式系统对于中国汛期降水具有很强的预报能力，其24 h 累积降水的月总降水分布很好地反应了汛期各时期主雨带的位置、强度及范围，同时该模式系统能够准确预报出独立降水事件的发生和发展，其中，长江中下游和东北地区预报降水与观测降水的时间位相吻合最好；除了5月和8月华北地区、5月西南东部地区、以及5月和6月长江中下游地区，AREMS/973模式系统预报的降水强度总体上弱于观测降水强度，且对于25 mm 以上量级的降水过程， 模式预报的降水范围小于观测降水范围。AREMS/973模式系统预报降水的能力随着降水量级的增大而减小，降水量级愈大，模式预报技巧愈低，对于50 mm 以上量级的降水过程，模式系统预报降水事件的发生概率类似于随机偶然事件的发生概率。5月，长江中下游地区降水预报略优于其他地区，其次是华南地区，6月雨带北移至江南和江淮地区，此时，长江中下游地区降水预报显著优于其他地区，7月末至8月华北雨季开始，降水预报最优区北移至华北地区，即AREMS/973模式系统降水预报最优区随着雨带的北移而北移，主雨带所在区域往往也是模式降水预报最优的地区。作者对此进行了初步探讨。     

云滴数浓度对超级单体龙卷影响的数值模拟研究

为了探讨云滴数浓度对于龙卷发生、发展的影响,利用ARPS（Advanced Regional Prediction System）模式,通过调整云滴数浓度（分别取高3000 cm-3、中1000 cm-3和低100 cm-3）的变化,对2003年7月8日安徽省无为县超级单体龙卷进行理想模拟试验。研究表明:三组试验都模拟出超级单体风暴的特征结构如钩状回波和V型入流缺口;云滴数浓度高的试验中上升气流更强、风暴较先发展且持续时间长,近地面涡度也较其他两组试验更大;从三组试验中找到4个龙卷涡旋,其中云滴数浓度高的试验中有两个,涡旋总持续时间接近30 min,最大近地面风速为46.93 m s-1,最大涡度值为0.42 s-1;高云滴数浓度情况下地面冷池弱,更有利于龙卷产生,并对龙卷的发生、发展有促进作用。     

Modern Agriculture in Advanced Placement Human Geography

Abstract

This article is an overview of the agriculture section in the outline of the Advanced Placement (AP) human geography course. It is intended to provide a more detailed framework on which teachers may develop their own curriculum for the AP class. Special emphasis is given to the practice of agriculture in contemporary industrial societies. It also encourages teachers to balance the cultural and historical views of agriculture contained in many textbooks with an economic and geographic focus. Agribusiness is also given special treatment.     

What Kind of Assessment for What Kind of Geography? Advanced Placement Human Geography*

This article raises awareness of the recently introduced Advanced Placement course in Human Geography by describing the design and management of assessment in the course. Standards are maintained through the choice of assessment instrument, the development of test items, scoring, and grade‐setting. The article contributes to a deeper understanding of the opportunities and threats of standardized testing within geography.     

Global Measurement of Sea Surface Temperature from Space: Some New Perspectives

The measurement of global sea surface temperature (SST) from space is well established with 20 years of useful data already acquired, but the more stringent sampling requirements and the higher degree of accuracy now demanded for applications in both climate monitoring and operational oceanography are increasingly difficult to meet with the standard meteorological polar orbiting sensors that have been the basic sensors used for global SST mapping. The established methods and sensors for measuring SST, both in situ and in space, are reviewed, compared, and their major limitations are identified. Mention is made of phenomena which complicate an apparently simple measurement, including diurnal stratification, the presence of clouds and the contamination of the stratosphere by volcanic aerosols. Recent developments in remote sensing of SST are mentioned, noting the improved microwave sensors now becoming available, the calibrated infrared sensors planned for geostationary platforms, and weighing the benefits of merging these data. The conventional buoy-calibration of SST measurements from space is complicated by the variable thermal structure of the upper few metres of the ocean. The recent improvement of radiometers for ship deployment has led to better understanding of the thermal skin of the ocean which suggests a new approach for the validation of SST algorithms based on radiation transfer models. Finally, a future strategy is outlined for combining measurements from many types of sensor in order to achieve the required accuracy and sampling rate of SST data products, and to identify some of the remaining scientific challenges in this field.     

ALI 遥感数据在岩矿信息提取中的应用研究

论文对研究区ALI数据进行了纯净像元提取,在此基础上,对纯净像元进行N-D散点图分析,选择出不同端元并进行归类分析,作为后期分类识别的样本.这里采用决策树方法对研究区岩矿进行识别,研究发现:样本区在MNF变换后图像上的波谱(前几个波段)可分性远远大于其在变换前图像上的波谱可分性,基于此的决策树分类方法能够识别出岩矿.     

Seismic design of space steel frames using advanced methods of analysis

A rational and efficient seismic design methodology for regular space steel frames using an advanced time domain finite element method of analysis that takes into account geometrical and material nonlinearities is presented. Seismic loads are applied in the form of Eurocode 8 spectrum compatible real accelerograms along the two horizontal directions of the frame. The iterative design procedure starts with assumed member sections, continues with the response checks for the damage, ultimate and service limit states and ends with the adjustment of member sizes so as all the response checks to be satisfied for all limit states. Thus, the proposed design method deals with nonlinearities and member interactions at the global level and consequently separate member capacity checks through the interaction equations of Eurocode 3 or the usage of the conservative and crude q-factor of Eurocode 8 are not required. Two numerical examples dealing with the design of (a) a space three storey steel frame with one bay in both horizontal directions and (b) a space seven storey steel frame with two and three bays along its two horizontal directions are presented to illustrate the method and demonstrate its advantages.