微地形上太阳辐射模拟及与地表温度关系研究

在微地形上进行太阳辐射模拟对于探讨起伏地表微气候因素分布具有重要意义,为分析微地形对太阳辐射的影响及对地表温度的影响,利用实时动态差分仪(real-time kinematic,RTK)实地测量实验样区的微地形,生成分辨率为0.1 m×0.1 m的分米级高精度数字高程模型(digital elevation model,DEM),模拟微地形下太阳总辐射的时空分布;同时结合地面温度实测数据,建立地表温度与太阳辐射的关系。结果表明:微地形下太阳辐射具有明显的空间分布特征,表现为沟脊大,沟底小;阳坡大,阴坡小;坡度越大接受的太阳辐射量越少;实验样区接受太阳辐射量大小依次为夏季春季秋季冬季;地形遮蔽效应对太阳辐射影响程度依次为冬季秋季春季夏季;地表温度与太阳辐射呈显著相关,相关系数为0.622。     

数字地面模型

数字地面模型杨德麟（清华大学土木系１０００８４）数字地面模型（ＤＴＭ）简称数模,是以数字的形式按一定的结构组织在一起,表示实际地形特征的空间分布模型,也是地形形状大小和起伏的数字描述。数字表示方式包括：离散点的三维坐标（测量数据）、由离散点组成的规则...     

数字高程模型地形描述精度量化模拟研究

在首先提出数字高程模型（DEM）地形描述误差（Et)概念的基础上，以我国5个不同地貌类型区为试验样区，采用比较分析的方法，研究EDEM地形描述误差的成因、影响因素、量测方法以及误差的数学模拟途径。统计分析的结果证明DEM地形描述误差与DEM空间分辨率及其地面粗糙度之间存在着线性相关关系，回归分析结果显示，DEM地形描述误差Et的均方差RMS值可以表达为DEM水平分辨率（R）与地面垂直曲率（V）的函数：RMS Et=(0.0063V 0.0066)R-0.022V 0.2415。该结果可用以估算估算所建立的DEM的地形描述精度，也为确定适宜的DEM分辨率提供了理论依据。     

DEM地形描述误差空间结构分析

数字高程模型（ＤＥＭ）是地理信息系统的核心数据之一。然而,ＤＥＭ误差的存在程度不同地影响地理信息系统空间分析的精度。本文首先说明ＤＥＭ地形描述误差的提取方法,通过误差地图以及量化研究方法,揭示ＤＥＭ误差的空间分布规律。试验结构显示误差地图是实现ＤＥＭ误差可视化的有效方法;ＤＥＭ地形描述误差具有很强的空间自相关性。自相关值随地形复杂度与ＤＥＭ分辨率的改变而有规律地变化。该结果为ＤＥＭ误差的估算与模拟     

绿色空间生态服务与地形因子的相关性分析

绿色空间生态服务(green space ecosystem services,GSES)与地形因子(坡度、海拔、坡向)有密切的关系,研究其关系对区域生态服务功能的修复、完善和可持续发展具有重要意义。通过奉化市绿色空间地类的划分和生态服务的计算模型获得GSES的价值。利用GIS技术提取坡度、海拔、坡向3个地形因子,同时分别获得每个因子对应的GSES值,最后选择Spearman相关分析模型对GSES价值与地形因子值进行检验。结果显示,奉化市GSES价值在空间上呈现出东北部、东南部GSES价值最低,西部、南部GSES价值较高的格局;GSES价值与地形因子的相关性强度表现为:坡度海拔坡向。同时由于海拔、坡度和坡向的变化导致温度、水分和太阳辐射在地表发生变化,并致使生态服务空间格局随海拔、坡度和坡向的变化呈现一定的规律性。     

基于SRTM-DEM区域地形起伏的获取及应用

 基于数字高程模型（DEM）空间分析方法，利用SRTM采集的DEM数据，提出两种获取区域地形起伏的关键技术，即高程条带法（Swath Profile）和高程阈值法（Threshold Value），并通过扩展区域地形起伏获取的技术方法，初步实现了黄土高原典型地区侵蚀量的定量化分析。     

顾及城区形态特征的太阳辐射传输模型及其遥感应用

准确量化地表太阳辐射量是反射率遥感反演之基础,开展城区表面辐射研究具有重要意义。本文选择天空视域因子（V）表征城区下垫面形态特征,并区分太阳直接辐射、天空漫辐射以及环境辐射的不同影响,构建了城区表面太阳辐射模型USSR（Urban Surface Solar Radiation）;然后,以Landsat 8可见光和近红外波段遥感数据为例,分析了USSR模型对于量化城区表面太阳辐射的应用前景。研究结论为：（1）USSR模型以天空视域因子为核心要素,清楚量化了城区表面各辐射分量,有效模拟了城区表面太阳辐射传输过程,能够较好地表达城区下垫面形态结构对入射辐射的影响;（2）将USSR模型应用于Landsat 8遥感数据可见光和近红外波段时,基于USSR模型估算得到的城区表面太阳辐射,与不考虑下垫面形态特征影响相比,前者可以较好地表达城区下垫面对入射辐射的“截留”作用;（3）USSR模型估算结果与TEB模型相比,二者具有较高的相关性,间接验证了USSR模型的可用性;（4）对USSR模型的V和下垫面反射率两变量进行敏感性分析,显示随着V值的增加,结果呈递增趋势;通常情况下的地表反射参数P设置值,相对于参数V的影响要弱,呈现不敏感性。本文提出的USSR模型可订正城区表面太阳辐射值,从而拓展城市遥感的应用深度和广度。     

基于DEM的水土流失分析

数字高程模型（DEM）是地理信息系统地理数据库中最为重要的空间信息资料和赖以进行地形分析的核心数据。数字地形模型从已知3维坐标的散乱点和已知高程的等高线出发,构筑地形表面,以数字的形式表示实际地形特征的空间分布,从而建立起相关区域内任一点的地形情况。利用数字高程模型进行宏观地形因子和微观地形因子的分析,直观地显示研究区域的地貌形态,为水土流失监测、分析、治理提供了重要的科学依据。     

复杂地形下太阳辐射计算工具的开发与验证

借鉴国内外利用DEM计算复杂地形下太阳辐射的模式,开发了一种运用ArcGIS 10.0支持的Add-In插件开发模式,计算复杂地形下太阳辐射的新的工具。利用该工具计算了黑河上游山区2011年全年的日太阳辐射值,并与ArcGIS本身的太阳辐射计算工具运算结果以及位于黑河上游葫芦沟流域的3个气象站点2011年的太阳辐射实测数据进行了比较分析。结果表明,该工具可很好地模拟太阳辐射的时空变异,且运算结果明显优于ArcGIS本身的太阳辐射计算工具。     

基于改进的MT-CLIM模型的中高纬低山丘陵区太阳辐射模拟——以小兴安岭为例

将DEM、坡度和坡向作为地形因子,基于ENVI/IDL编写MT-CLIM模型批量处理程序,使用改进MTCLIM模型对小兴安岭地区的地面气象台站进行太阳辐射模拟,并将模拟结果分别与辐射台站实测数据和二次趋势面统计模型进行验证。研究结果表明:从整年上,其与辐射台站的拟合精度R2为0.813 3,其中,夏季模拟太阳辐射日值拟合精度偏低,而其与二次趋势面统计模型拟合精度R2值范围为0.571 3~0.793 3;采用改进的MT-CLIM模型模拟较大区域的太阳辐射,比统计模型具有更好的普适性和高效性,能获得较好的中高纬低山丘陵区模拟效果,且为森林生态过程模型的输入参数研究提供依据。     

Mapping solar energy potential of southern India through geospatial technology

Abstract

There is an urgent need for alternate energy resources throughout the world due to the decline in the accessibility of fossil fuels and other conventional resources. In this pursuit, solar energy offers a favourable solution and can easily be converted into energy. There are some solar radiation models which provide point and area-based computations based on the geometry of surface orientation and visible sky. The work comprises the mapping of the solar energy generation potential of southern India to balance the competing and upcoming energy demands. The current work explores and employs the geospatial technology to prepare solar energy potential map to deliver the valuable inputs to the energy sector. The research was supported with satellite-derived global solar radiation and temperature data over a span of one year. The values obtained from the spatial radiation models were processed to get the improved datasets. Suitable cartographic visualization of solar insolation parameters was presented for enhanced understanding of the spatial distribution of solar potential, PV output, air-temperature or other spatial characteristics. Twelve monthly maps, an annual map, and another map with the location of the measurement stations were created to unravel a number of unturned mystery about the understanding of solar resource diversity in a spatial context, which will support our decisions & arguments for any kind business.     

A New 3‐D Solar Radiation Model for 3‐D City Models

Estimates of solar radiation distribution in urban areas are often limited by the complexity of urban environments. These limitations arise from spatial structures such as buildings and trees that affect spatial and temporal distributions of solar fluxes over urban surfaces. The traditional solar radiation models implemented in GIS can address this problem only partially. They can be adequately used only for 2‐D surfaces such as terrain and rooftops. However, vertical surfaces, such as facades, require a 3‐D approach. This study presents a new 3‐D solar radiation model for urban areas represented by 3‐D city models. The v.sun module implemented in GRASS GIS is based on the existing solar radiation methodology used in the topographic r.sun model with a new capability to process 3‐D vector data representing complex urban environments. The calculation procedure is based on the combined vector‐voxel approach segmenting the 3‐D vector objects to smaller polygon elements according to a voxel data structure of the volume region. The shadowing effects of surrounding objects are considered using a unique shadowing algorithm. The proposed model has been applied to the sample urban area with results showing strong spatial and temporal variations of solar radiation flows over complex urban surfaces.     

Incorporating dynamic factors for improving a GIS‐based solar radiation model

Solar radiation has been a major input to agricultural, hydrological, and ecological modeling. However, solar radiation is usually influenced by three groups of dynamic factors: sun–earth position, terrain, and atmospheric effects. Therefore, an integrated approach to accurately consider the impacts of those dynamic factors on solar radiation is essential to estimate solar radiation over rugged terrain. In this study, a spatial and temporal gap‐filling algorithm was proposed to obtain a seamless daily MODIS albedo dataset. A 1 km‐resolution digital elevation model was used to model the impact of local topography and shading by surrounding terrain on solar radiation. A sunshine‐based model was adopted to simulate radiation under the influence of clouds. A GIS‐based solar radiation model that incorporates albedo, shading by surrounding terrain, and variations in cloudiness was used to address the spatial variability of these factors in mountainous terrain. Compared with other independent solar radiation products, our model generated a more reliable solar radiation product over rugged terrain, with an R² of 0.88 and an RMSE of 2.55 MJ m^?2 day^?1. The improved solar radiation products and open source app can be used further in practice or scientific research.     

起伏地形下我国太阳直接辐射空间制图

建立了起伏地形下太阳直接辐射分布式计算模型 ;成功地解决了起伏地形中地形相互遮蔽对太阳直接辐射影响的难题 ;采用数据集群技术 ,探讨了不同数据集情况下太阳直接辐射计算模式的时空有效性 ;以 1km× 1km分辨率的DEM数据作为地形的综合反映 ,完成了我国 1km× 1km分辨率各月气候平均太阳直接辐射空间分布制图     

A method of downscaling temperature maps based on analytical hillshading for use in species distribution modelling

Climate maps have been widely used for the construction of species distribution models. These maps derive from interpolation of data collected by meteorological stations. The sparse distribution of stations generates maps with coarse spatial resolution that are unable to detect microclimates or areas that can serve as plant or animal refuges. This work proposes a method for downscaling temperature maps using the solar radiation falling upon hillsides as predictor for the influence of relief on local variability. Solar irradiance is estimated from a digital elevation model of the study area using a routine based on analytical hillshading. Some examples of downscaling from 1 km to 25 m spatial resolution are shown. The results are compared with the surface temperature maps from Landsat 8 satellite imagery.     

基于NOAA卫星的陕西省太阳总辐射反演研究

本文以2007年3-9月陕西省地面总日射实测小时累计值及NOAA卫星影像为信息源,采用半物理模式的统计经验反演得出地面太阳总辐射,进而分析了陕西省地面总日射的分布状况.对反演结果与地面辐射站实测结果进行比较,平均相对误差为8.43%.     

A New GIS-based Solar Radiation Model and Its Application to Photovoltaic Assessments

The solar radiation model r.sun is a flexible and efficient tool for the estimation of solar radiation for clear‐sky and overcast atmospheric conditions. In contrast to other models, r.sun considers all relevant input parameters as spatially distributed entities to enable computations for large areas with complex terrain. Conceptually the model is based on equations published in the European Solar Radiation Atlas (ESRA). The r.sun model was applied to estimate the solar potential for photovoltaic systems in Central and Eastern Europe. The overcast radiation was computed from clear‐sky values and a clear‐sky index. The raster map of the clear‐sky index was computed using a multivariate interpolation method to account for terrain effects, with interpolation parameters optimized using a cross‐validation technique. The incorporation of terrain data improved the radiation estimates in terms of the model's predictive error and the spatial pattern of the model outputs. Comparing the results of r.sun with the ESRA database demonstrates that integration of the solar radiation model and the spatial interpolation tools in a GIS can be especially helpful for data at higher resolutions and in regions with a lack of ground measurements.     

一个植被双向反射模式的反演控制试验

利用地面遥感观测数据,对一个浑浊介质假定下的植被双向反射模式,增加了对太阳漫射辐射因素处理,在可见光波段上,进行了系列模式反演试验。这些试验有助于完善植被双向反射模式中物理过程的描述,了解模式反演过程的控制和选择合适遥感观测数据进行模式反演。分析试验结果发现：（１） 对 Ｌ Ａ Ｉ进行初值预估有利于获得较好的植被双向反射模式反演结果。（２） 加入植被对太阳漫射辐射的反射过程描述,可以使植被双向反射模式的反演结果更加合理。（３） 使用在太阳天顶角不太大（ ＜ ４５°） 和太阳方位角偏离１８０°不多（ ＜ ４５°） 观测条件下得到的遥感数据,可以使植被双向反射模式的反演结果较好。（４） 在３１°—６１°的太阳天顶角范围和１３６°—２５８°的太阳方位角范围内,多角度观测使太阳天顶角和方位角因素对 Ｌ Ａ Ｉ反演结果的影响不显著。（５） 当太阳漫射辐射的份额不大时,对 Ｌ Ａ Ｉ反演结果的影响不显著。如果只针对 Ｌ Ａ Ｉ,那么对反演植被双向反射模式所应用的地面遥感数据可以不进行大气校正处理,这样的结果虽然是从对地面遥感数据的处理中获得的,仍然对卫星遥感的观测时段选择和卫星遥感数据的选取和分析有一定的价值。     

Impact of aerosols on terrestrial gross primary productivity in North China using an improved boreal ecosystem productivity simulator with satellite-based aerosol optical depth

ABSTRACT

Atmospheric aerosols can alter the direct and diffuse components of global solar radiation, which further influences terrestrial gross primary productivity (GPP) via photosynthesis. To investigate the impact of aerosols on GPP, GPP is modeled using the Boreal Ecosystem Productivity Simulator (BEPS) under two aerosol scenarios (S1& S2) over cropland and grassland ecosystems in the highly polluted North China. In S1, the aerosol-effect is not considered and an original empirical method is used when estimating direct and diffuse solar radiation in BEPS. In S2, BEPS is improved by a new empirical method which incorporates the impact of aerosols using the remote sensing-based aerosol optical depth (AOD). Results suggest that aerosols can reduce GPP of the sunlit leaves by decreasing direct solar radiation, but increase GPP of the shaded leaves by increasing diffuse solar radiation. The impact of aerosols on GPP is more significant over the cropland ecosystem (p < 0.05) with a more complex canopy structure during the peak period of the growing season. Furthermore, an AOD value of 0.3–0.6 with a diffuse fraction (the fraction of diffuse solar radiation in global solar radiation) around 30-40% can largely increase total GPP over the cropland ecosystem. The study improves the accuracy of GPP modeling using BEPS by highlighting the aerosol-effect on GPP via solar radiation over highly polluted regions.

Abbreviations: gross primary productivity (GPP); aerosol optical depth (AOD); boreal ecosystem productivity simulator (BEPS)     

电离层异常原因分析与建模

分析了地震、磁暴、太阳耀斑等自然现象引发电离层异常的物理机制,并总结了电离层异常的特点。针对电离层中电子分布受地磁、太阳热辐射和地壳变动等影响较大,基于抛物层和赤道双峰模型建立了电子密度呈高斯型分布的电离层异常模型,为进一步研究电离层异常的耦合机制提供了依据。