Deriving the slope-mean shielded astronomical solar radiation spectrum and slope-mean possible sunshine duration spectrum over the Loess Plateau

Solar radiation is often shielded by terrain relief, especially in mountainous areas, before reaching the surface of the Earth. The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR) and the possible sunshine duration(PSD) over the Loess Plateau. To this end, we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform. In each test area, 5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope, SASR and PSD. Then, we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum, and proposed a method to extract them from the computed slope, SASR and PSD over rectangular analysis windows. Using this method, we found both spectrums in a year or in a season for each of the four seasons in the six test areas. Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum. The values of the two spectrums decreased when the slope increased.Furthermore, the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature. The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD. All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures. This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.

基于大气状态参数的太阳光谱模型与测试方法研究

针对影响光伏组件发电性能的太阳光谱光功率预测系统直接测试难问题,基于温度、相对湿度和压力等大气状态参数,提出了一个新的简单地面太阳光谱的量化计算模型。通过设计实验对比常州地区直接测量与模型计算得到的地面太阳光谱,分析了模型计算光谱方法的适用性和局限性,并探讨该模型为光伏组件的输出性能精确评估的应用。研究结果表明晴天天气可见光波段,测量光谱与计算光谱之间的相对误差保持在5%以内;阴天天气比晴天天气适用性较差,但也保持在20%以内;不同季节对模型的适用性影响不大,相对误差保持在10%以内。

使用6S模型由GMS5卫星资料反演陆地大气气溶胶光学厚度

采用每日08、11、14、17时(北京时)地面气象观测资料、卫星资料,应用6S辐射传输模型(second simulation of satellite signal in the solar spectrum)建立一幅晴空条件下4个时次的大气辐射参数背景底图。利用辐射传输理论,在辐射参数(背景底图上)与大气气溶胶光学厚度(aerosol op-tical depth,AOD;任意一天与背景底图同时次)之间建立了闭合一元非线性方程,求解方程得到晴空条件下陆地大气气溶胶光学厚度。选用一月内的GMS5-VISSR可见光通道资料,按上述方法得到选定时间段内的每日08、11、14和17时北京气象观测站位置处的550 nm晴空大气气溶胶光学厚度。反演得到的晴空AOD值可以反映1个月内气溶胶光学厚度的日变化规律。另外,在中国大陆范围内划定反演试验区域,选择试验区域内的气象站所在位置为反演点,制作底图,并求算2002年5月1—17日、7月13日—8月14日站点位置的AOD。由站点值插值到整个反演试验区域内,所得结果反映出任意时次反演试验区内的气溶胶空间分布情况。

研究太阳分离活动体光谱不对称轮廓的“多云模型”方法和应用

本文提出了处理分离的太阳活动体光谱不对称轮廓的一种方法──“多云模型”方法。在某些假设和一定的近似条件下利用本文提出的方法可同时得到太阳多个分离活动体的视向速度Ｖ，多普勒线宽△λ_Ｄ和线心光学深度τ_０，源函数Ｓ的近似值。文章给出了该方法的几个应用实例并进行了讨论。研究表明，计算所得的Ｖ和△λ_Ｄ的值是较为可靠的，二云模型是处理由两个分离活动体沿视线重叠而产生的不对称轮廓较为有效的方法。

基于可见光图像的近红外场景仿真

利用地物光谱仪采集了晴天条件下典型地物在380-1100 nm的光谱反射率,并利用经过定标后的CMOS相机采集典型地物不同时段的可见光、近红外图像,结合相机辐射定标结果和地物目标的反射率建立了可见光、近红外图像灰度值的映射关系,且对简单场景进行图像分割,并通过查找表快速将可见光图像转化为近红外图像。建立了太阳辐射模型,在反演精度要求不是很高的条件下,可以反演一天内任意时刻的近红外图像。仿真结果表明,本文方法可生成真实感较好的近红外图像,为后续的各时段、各种天气条件及多种地物的近红外场景仿真奠定基础。

在轨超高分辨率傅里叶光谱仪仪器线型函数更新方法研究

仪器线型函数是傅里叶光谱仪重要的物理表征参数之一,影响仪器测量光谱的精度.随着空间测量和大气探测等遥感应用在高精度上的需求,如何实时在轨测量并更新星载光谱仪的仪器线型函数,成为当前提高在轨超高分辨率光谱仪测量精度的重要手段.以傅里叶型光谱仪为例,根据仪器线型函数的原理,利用在轨超高分辨率光谱仪实测太阳光谱定标数据不受大气气溶胶影响且具有独立太阳弗朗和费线的特征,来对在轨超高分辨率光谱仪的仪器线型函数进行监督和更新.实验以Kurucz太阳光谱模型作为参考光谱,在对应波段范围内分别选取多条实测太阳定标光谱和参考光谱的特征峰,通过调整光谱仪的狭缝模型,对特征峰残差进行迭代对比,演算出仪器ILS参数变化.最后,用更新的仪器线型函数与临边理论光谱卷积,与实测临边定标光谱比较验证,误差范围在-6%~8%.结果表明,该方法可为在轨超高分辨率光谱仪仪器线型函数的监督更新提供参考依据.

月表可照时间谱和太阳辐射谱空间分布特征研究

以20 m分辨率的月球数字高程模型(Digital Elevation Model,DEM)为数据源,在不同的纬度区域选取了16个典型月貌样区,基于数据并行技术定量计算月表实际起伏地形下2020年的可照时间和太阳辐射。源于数字地形分析中的坡谱模型,采用矩形窗口扩张法提取了不同地貌样区的稳定坡度–年平均可照时间谱、坡度–年平均太阳辐射谱、坡向–年平均太阳辐射谱以及稳定面积。结果表明:月表太阳辐射和可照时间的空间分布受地形要素影响显著;月表可照时间和太阳辐射整体呈现出随纬度增大而逐渐减小的分布特征;各样区稳定面积与坡度的变异系数呈正相关关系。研究结果可为未来月球基地建设选址提供支持。

Biomimetic Material Simulating Solar Spectrum Reflection Characteristics of Yellow Leaf

To counter the threat of hyperspectral detection, it is necessary to develop biomimetic materials to simulate the solar spectral re- flection characteristics of plant leaf accurately. Two kinds ofmembranaceous yellow biomimetic materials were prepared by dispersing the particles of chrome titanium yellow and iron oxide yellow as fillers in polyvinyl alcohol films respectively. Reflectance and transmittance of the biomimetic materials were measured, and absorption and scattering coefficients of the biomimetic materials were inverted with a four-flux model. Results indicate that the biomimetic material adopting chrome titanium yellow particles can simulate the solar spectrum reflection characteristics of yellow leaf because of the similar absorption and scattering characteristics. The biomimetic material adopting iron oxide yellow particles cannot simulate the spectrum reflection characteristics of yellow leaf near the wavelength of 900 nm due to the characteristic absorption of the iron oxide. When the volume fraction of the chrome titanium yellow particles is lower than 2.12%, the absorption and scattering coefficients both increase approximately linearly with the volume fraction, indicating that the particles can scatter radiation independently. Therefore, the reflectance of the biomimetic material can be regulated through linearly changing of the volume fraction of the chrome titanium yellow particles.

基于Drude-Lorentz模型的金银纳米颗粒光谱特征研究

基于Drude-Lorentz模型,利用最小二乘法得到了金银纳米材料介电常数的最优表达式。结合Mie理论,系统研究了球形金银纳米颗粒的消光光谱、吸收光谱、散射光谱等特性,比较并分析了不同尺寸下金银纳米颗粒的散射消光比等光谱特性。研究表明:(1)随着金纳米颗粒尺寸的增大,散射作用随之加强,入射波长为529 nm时发生表面等离激元共振,半径为10 nm、20 nm、30 nm、40 nm、50 nm理想金纳米球体的散射消光比依次为0.76%、5.65%、12.81%、19.36%和37.13%;(2)银纳米颗粒对入射光的消光作用相对金纳米颗粒更为显著,散射作用的贡献比重更大,入射波长为415 nm时,半径依次为10 nm、20 nm、30 nm、40 nm、50 nm理想银纳米球体的散射消光比依次为17.85%、63.46%、85.44%、93.29%和96.45%,且随着入射波长的增加,散射消光比逐步提高。