月球紫外-可见-近红外反射光谱的基本特征及解析方法

月球紫外-可见-近红外反射光谱(强度,反照率以及吸收特征)是研究月球表面物质组成的重要手段.文章简要介绍了月球表面反射光谱的基本特征、形成机制以及现有月球反射光谱数据及其解析方法.这些方法主要有光谱参数、连续背景扣除、高斯反卷积分析以及主成分分析.还讨论了高光谱探测器在月球探测中的应用前景、已有方案以及获取新的月球样品对月球反射光谱研究的重要性.     

月球紫外-可见-近红外反射光谱的基本特征及解析方法

月球紫外一可见一近红外反射光谱(强度,反照率以及吸收特征)是研究月球表面物质组成的重要手段。文章简要介绍了月球表面反射光谱的基本特征、形成机制以及现有月球反射光谱数据及其解析方法。这些方法主要有光谱参数、连续背景扣除、高斯反卷积分析以及主成分分析。还讨论了高光谱探测器在月球探测中的应用前景、已有方案以及获取新的月球样品对月球反射光谱研究的重要性。     

各向异性反射对基于光谱混合分析的植被盖度估算的影响

光谱混合分析法是解决亚像元植被盖度反演估算问题最行之有效的方法,线性光谱混合分析又是其中最常用的研究手段。传统观点认为基于线性光谱混合分析的植被盖度估算精度主要受多重散射和端元光谱可变性的影响,而且各向异性反射这个地物表面所固有的特性也常常被忽略。研究设计了由寸苔草、沙和水3种地物类别组成的棋盘式混合地物反射率光谱测试方案,在探讨分析传统的多重散射与端元光谱可变性的基础上,进一步分析评价了各向异性反射对基于光谱混合分析的植被盖度估算的影响。结果表明,各向异性反射是不可忽视的,在最小化多重散射及端元光谱可变性的影响后,考虑各向异性反射后寸苔草盖度估算精度显著提升,均方根误差RMSE下降了52%。研究不仅证实了各向异性反射在植被盖度估算问题中的重要性,还印证了其是同种端元类型光谱差异性的另一重要来源,拓宽了端元光谱可变性的范畴,为利用光谱混合分析法更准确地进行植被盖度估算提供了新的思路和方法。     

月球表面钛的研究进展

月球表面(尤其是月海玄武岩)蕴藏有丰富的钛铁矿,因此对月球表面Ti含量进行研究十分的重要。本文总结了目前已有的利用UV、VIS和NIR光谱进行月表Ti含量的反演机理和方法,特别是发展比较成熟的光谱比值反演方法的机理和反演步骤,该工作为我国利用嫦娥工程的干涉成像光谱仪的科学数据开展月表Ti含量的反演研究奠定了坚实的基础,最后针对我国的干涉成像光谱仪数据提出了研究Ti含量的思路与方法。     

基于SPIS的月球表面充电模拟研究

目的研究月球表面不同等离子体环境下航天器表面充放电效应情况。方法利用欧空局开发的SPIS软件建模,并仿真模拟,通过分析表面电流种类、大小,得出不同环境下的一般性的充放电规律。结果月球表面探测器存在表面充电风险,磁鞘层、磁尾瓣、等离子体片及太阳风4种不同典型等离子体环境下表面充电电位差异较大,连接处充电电位存在分布不均匀的渐变现象。表面充电电位区间约为-1784~142 V。结论光照条件能显著影响探测器表面电位,特殊区域充电电位会受到临近区域充放电效应形成的新的小范围等离子体环境的影响。     

赤潮对近岸水体生物光学特性的影响

研究了赤潮对近岸水体生物光学特性的影响.从大连湾采集11个站位的水体生物光学数据,分析了赤潮发生时生物要素、反射光谱以及吸收光谱的变化特征.结果表明,大连湾本次赤潮由微微型藻类引起;赤潮对水体遥感反射率的光谱形状影响明显,与正常水体相比,由于高浓度叶绿素a的强吸收作用,导致440、632 nm波段附近出现反射谷,红光波...     

胡敏酸衰减全反射-傅里叶变换-红外光谱研究

胡敏酸是土壤有机质的重要组成部分。胡敏酸的物化结构和特性直接影响其环境地球化学行为,因此,也是胡敏酸地球化学研究的重要内容。傅里叶变换-红外光谱是胡敏酸物化结构和性质研究的强大工具,以往的研究通常采用压片-透射吸收法来研究分析胡敏酸的有机官能团信息。本工作采用透射-傅里叶变换-红外光谱和衰减全反射-傅里叶变换-红外光谱两种分析方法对比研究了黄壤和石灰土中胡敏酸的有机官能团信息。结果表明,两种分析方法给出完全一致的研究结果,即:黄壤胡敏酸脂肪碳含量较高,芳香结构含量较低;石灰土胡敏酸分子的脂肪碳含量较低,芳香结构和含氧官能团含量较高。比较而言,衰减全反射-傅里叶变换-红外光谱操作简便,无需对待测胡敏酸样品进行预处理,可以广泛地应用于胡敏酸红外光谱的分析。     

复杂环境下具有轨道特征目标模型光散射特性研究

依据目标表面材料光谱反射率、等效光学常数色散曲线和双向反射分布函数（BRDF）及表面高度起伏均方根,建立了理论模型,计算分析了一种空间简单体组合模型在太阳、地球-大气系统背景影响下目标可见光散射特性随入射波长和轨道高度的变化关系。计算结果表明,散射体在相同轨道的条件下,表面材料的反射率越高,光散射强度越大;散射体材料相同时,散射体散射强度随着散射体轨道高度的增加而减小。     

胡敏酸衰减全反射-傅里叶变换-红外光谱研究

胡敏酸是土壤有机质的重要组成部分。胡敏酸的物化结构和特性直接影响其环境地球化学行为,因此,也是胡敏酸地球化学研究的重要内容。傅里叶变换-红外光谱是胡敏酸物化结构和性质研究的强大工具,以往的研究通常采用压片-透射吸收法来研究分析胡敏酸的有机官能团信息。本工作采用透射-傅里叶变换-红外光谱和衰减全反射-傅里叶变换-红外光谱两种分析方法对比研究了黄壤和石灰土中胡敏酸的有机官能团信息。结果表明,两种分析方法给出完全一致的研究结果,即:黄壤胡敏酸脂肪碳含量较高,芳香结构含量较低;石灰土胡敏酸分子的脂肪碳含量较低,芳香结构和含氧官能团含量较高。比较而言,衰减全反射-傅里叶变换-红外光谱操作简便,无需对待测胡敏酸样品进行预处理,可以广泛地应用于胡敏酸红外光谱的分析。     

月球尘环境模拟试验方法研究

在调研国外月球环境地面模拟试验的基础上,分析了月球尘环境对于月面探测设备可能的影响以及开展月球尘地面模拟试验的意义和价值。以美国Apollo计划带回的月球尘样品为例,研究了月球尘的物理特性与化学成分,并对国外现有月球尘模拟产品情况进行了分析。对于极端环境条件下月球尘特性可能发生的变化和危害进行了分析。最后针对月球尘环境的特点,提出了从制备月球尘产品到环境参数模拟与控制到试验参数采集、分析与修正的一整套月球尘环境模拟试验方案。     

月球上发现固态水

月球勘探者’在月球两极发现水冰的存在 ,不仅为人类在月球上建立维持生命系统 ,而且为我们研究地球上水的来源提供了新的线索。本文简明介绍了月球上固态水的探测、分布区、来源及其意义。     

二氧化硫对棉花叶片光谱反射特性的影响

在动态熏气箱中对棉株进行SO_2处理(2ppm,8小时).测定叶片光谱反射率和微分光谱.受SO_2伤害的棉叶光谱反射率发生变化:在可见光部分,反射率普遍增加;在近红外部分,反射率降低.整个光谱反射曲线发生蓝移,初步确定几个波段可用于区别污染的与正常的棉叶光谱反射特性.     

土壤中过量铜对水稻叶片光谱反射特性的影响

水稻移栽于添加不同量铜(分别为50、100、400ppm)的土壤上,叶片光谱反射特性发生规律性变化。在可见光部分反射率提高;在近红外部分反射率下降;在光谱反射率曲线的微分图上显示出蓝移。这些变化在分蘖期最为显著。从几个波段可以看出,正常的与铜毒害的水稻的光谱反射特性有较大差异。     

Coadaptive changes in physiological and biophysical traits related to thermal stress in web spiders

Web spiders are considered to have expanded their habitats from dim to bright environments during the evolutionary history. Because they are sedentary predators exposed to the sun, they may have developed a suite of adaptive traits to cope with thermal stress. We examined the critical thermal maximum, spectral reflectance of solar energy by the body surface, and surface–volume ratio (SVR) for 11 spider species. Analysis of the four genera having a pair of species inhabiting both bright and dim environments showed that species in bright environments exhibited higher lethal temperatures, but spectral reflectance and SVR did not differ. Independent contrasts using the 11 species indicated that critical thermal maximum was positively correlated with spectral reflectance and spectral reflectance was negatively correlated with SVR. These results suggest that physiological tolerance to high temperatures and a biophysical mechanism to reduce heat gain evolved jointly during the history of habitat expansion in araneoid spiders.     

基于实测光谱的杭州湾悬浮物浓度遥感反演模式

悬浮物是我国近海水质遥感监测的主要参数之一.利用ASD地物光谱仪测量杭州湾水体的反射光谱,同步采集表层水样获取悬浮物浓度,模拟水色卫星MODIS和MERIS的波段设置提取遥感反射率,基于人工神经网络分别建立2种悬浮物浓度的遥感反演模式.实测结果表明,杭州湾水体中悬浮物浓度较高,泥沙含量远远大于叶绿素浓度,平均值分别为705 mg/L和1.164 mg/m³;2个监测站位的悬浮物浓度表现出时空上的差异,尤其是随潮汐变化的短周期变异十分显著;实测水体反射率光谱曲线在650～700 nm之间与800 nm附近分别出现峰值,光谱曲线一阶微分结果显示第一反射峰的位置随着悬浮物浓度增大向长波方向移动.基于神经网络建立的模拟算法充分利用了卫星不同通道的光谱信息,可以同时模拟水体中色素与非色素悬浮物的浓度,模型取得了较好的拟合效果,R²均大于0.95,可以应用于实际卫星遥感反演,尤其是MERIS数据,因其具有相对较高的空间分辨率,在近海水环境遥感监测中的应用前景更为广阔.     

Die Geologie des Mondes

A summary of lunar geology. Light feldspathic rocks which constitute the highland areas are components of the primeval crust of the Moon. Dark pyroxeneand ilmenite-rich basaltic lava flows — resulting from partial melting processes in the lunar mantle — filled the Maria basins, 3.1–3.9 × 10⁹ years ago. Craters of all sizes and large circular basins were formed by impacting bodies from outside which produced the regolith blanket — a mass of comminuted rocks with fragments of impact breccias, impact melt glasses and impact melt rocks.     

Spectral characteristics of plant communities from salt marshes:A case study from Chongming Dongtan,Yangtzeestuary,China

The spectral reflectance of recently formed salt marshes at the mouth of the Yangtze River, which are undergoing invasion by Spartina alterniflora, were assessed to determine the potential utility of remotely sensed data in assessing future invasion and changes in species composition. Following a review of published research on remote sensing of salt marshes, 53 locations along three transects were sampled for paired data on plant species composition and spectral reflectance using a FieldSpec™ Pro JR Field Portable Spectroradiometer. Spectral data were processed concerning reflectance, and the averaged reflectance values for each sample were reanalysed to correspond to a 12-waveband bandset of the Compact Airborne Spectral Imager. The spectral data were summarised using principal components analysis (PCA) and the relationships between the vegetation composition, and the PCA axes of spectral data were examined. The first PCA axis of the reflectance data showed a strong correlation with variability in near infrared reflectance and ‘brightness’, while the second axis was correlated with visible reflectance and ‘greenness’. Total vegetation cover, vegetation height, and mudflat cover were all significantly related to the first axis. The implications of this in terms of the ability of remote sensing to distinguish the various salt marsh species and in particular the invasive species S. alterniflora were discussed. Major differences in species with various physiognomies could be recognised but problems occurred in separating early colonising S. alterniflora from other species at that stage. Further work using multi-seasonal hyperspectral data might assist in solving these problems.     

Crustal evolution in the silicate planets

This paper reviews recent discoveries from space missions to the Moon, Mercury, Mars, and Venus, and their implications for planetary development. It appears that all these planets have undergone similar sequences of crustal evolution, the chief difference among them being how far each has evolved. All have apparently undergone a first differentiation in which a global crust was formed. This crust was partly disrupted by heavy impact bombardment some 4·10⁹ years ago. A second differentiation, resulting in basalt eruptions, followed. The Moon and Mercury essentially stopped evolving at this point; Mars and Venus continued to a stage of incipient plate tectonics, with crustal fracturing and vulcanism. Terrestrial Precambrian geologic evidence is consistent with a similar but further-advanced evolutionary sequence for the Earth as well, and the theory is proposed that terrestrial continents are the greatly altered and redifferentiated remnants of an originally global igneous crust of intermediate composition. The ocean basins of today are the multi-cyle descendants of mare-like basins localized by a late heavy bombardment about 4·10⁹ years ago analogous to that which formed the lunar mare basins and similar basins on other planets.     

An epicuticular multilayer reflector generates the iridescent coloration in chrysidid wasps (Hymenoptera, Chrysididae)

Chrysidid wasps in the subfamily Chrysidinae are brood parasitoids or cleptoparasites of other insects and famous for their cuticular iridescence. In this study, we examine the dorsal abdominal cuticle of the chrysidid wasp Hedychrum rutilans to identify the underlying color mechanism. Using scanning electron microscopy, reflectance spectral analysis, and theoretical calculations, we demonstrate the presence of an epicuticular multilayer reflector consisting of six lamellae with a thickness of 185 nm each. The lamellae exhibit a rough surface probably functioning as spacers between the individual layers. The reflector has a measured reflectance maximum at λ = 630 nm, i.e., in the red part of the visible spectrum of light at normal incidence and the reflectance maximum shifts to green as the angle of incidence increases. Complementary theoretical modeling corroborates the view that the epicuticular multilayer generates the iridescent color of the chrysidid cuticle. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.