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1.
Recent studies in Amazonian tropical evergreen forests using the Multi-angle Imaging SpectroRadiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) have highlighted the importance of considering the view-illumination geometry in satellite data analysis. However, contrary to the observed for evergreen forests, bidirectional effects have not been evaluated in Brazilian subtropical deciduous forests. In this study, we used MISR data to characterize the reflectance and vegetation index anisotropies in subtropical deciduous forest from south Brazil under large seasonal solar zenith angle (SZA) variation and decreasing leaf area index (LAI) from the summer to winter. MODIS data were used to observe seasonal changes in the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Topographic effects on their determination were inspected by dividing data from the summer to winter and projecting results over a digital elevation model (DEM). By using the PROSAIL, we investigated the relative contribution of LAI and SZA to vegetation indices (VI) of deciduous forest. We also simulated and compared the MISR NDVI and EVI response of subtropical deciduous and tropical evergreen forests as a function of the large seasonal SZA amplitude of 33°. Results showed that the MODIS-MISR NDVI and EVI presented higher values in the summer and lower ones in the winter with decreasing LAI and increasing SZA or greater amounts of canopy shadows viewed by the sensors. In the winter, NDVI reduced local topographic effects due to the red-near infrared (NIR) band normalization. However, the contrary was observed for the three-band EVI that enhanced local variations in shaded and sunlit surfaces due to its strong dependence on the NIR band response. The reflectance anisotropy of the MISR bands increased from the summer to winter and was stronger in the backscattering direction at large view zenith angles (VZA). EVI was much more anisotropic than NDVI and the anisotropy increased from the summer to winter. It also increased from the forward scatter to the backscattering direction with the predominance of sunlit canopy components viewed by MISR, especially at large VZA. Modeling PROSAIL results confirmed the stronger anisotropy of EVI than NDVI for the subtropical deciduous and tropical evergreen forests. PROSAIL showed that LAI and SZA are coupled factors to decrease seasonally the VIs of deciduous forest with the first one having greater importance than the latter. However, PROSAIL seasonal variations in VIs were much smaller than those observed with MODIS data probably because the effects of shadows in heterogeneous canopy structures or/and cast by emergent trees and from local topography were not modeled. 相似文献
2.
快速准确地获取土地利用/覆被信息是遥感领域研究的一个热点课题.本文用5种决策树分类器及MISR多角度数据,对塔里木河下游地区进行土地覆被分类研究.通过对不同波段和观测角数据组合形成的6个数据集进行分类比较发现:(1)无论使用哪种分类器,相比于天底角观测方式,多角度观测都能获得更高的分类精度,特别是能显著提高灌木,林地和草地类型的分类精度,说明多角度观测能有效地反映地物的反射异质性信息,更好地区分地物.(2)与MLC分类法相比,决策树算法的分类精度更高,特别是随机森林和C 5.0方法最为突出,说明决策树的分类能力要优于MLC法.使用多角度数据集时,这种差别更明显,说明决策树能更有效地利用多角度信息.(3)4种决策树算法(J48,Random Forest,LMT,C 5.0)使用近红外波段的分类效果好于使用红光波段的分类效果,说明近红外波段能提供更多的地物反射异质性信息. 相似文献
3.
WU YunZhao LU HuaYu & LIU Qiang School of Geographic Oceanographic Sciences Nanjing University Nanjing China 《中国科学:地球科学(英文版)》2010,(4)
Deserts,which have high surface albedo and wide area,are important components of the earth system.It is very important for the research of surface radiation and energy balance to understand the anisotropic scattering of desert areas.The emergence and development of multi-angle remote sensing made possible the inversion of the anisotropic scattering of desert areas at the regional or global scale.Firstly,this paper explored the accuracy of the inversion of asymmetry factor using the Hapke model and the simul... 相似文献
4.
天山典型林带积雪的多角度遥感识别 总被引：1，自引：1，他引：0
天山中段的山地针叶林带很大程度上影响了该地区整体卫星雪盖的识别精度,多角度卫星遥感技术的发展为林区积雪识别提供了新的途径。本文选取了2000年4月至2001年6月,10个时段研究区内无云覆盖的(Multi-angle Imaging Spectro Radiometer)MISR多角度数据,首先对红光波段不同角度观测结果组成的角度谱图像进行非监督分类,以确定天山林带的分布区域,然后在玛纳斯河中下游与那拉提山东部选取典型像元,分析这些像元红光波段各角度反射率在林区不同积雪覆盖状况下的表现差异。研究发现,若林区存在积雪,0°,±26.1°,±45.6°五个观测角度反射率的平均值大于0.1,在部分降雪月份,后向45.6°观测的反射率大于天顶方向观测的2.5倍。根据这一结论,给出基于MISR数据的研究区不同时段的积雪识别结果。结果表明,MISR红光波段对林区积雪反应敏感,不同角度观测的反射率在林区有雪和无雪时差异较大,故可利用多角度遥感信息进行林区积雪识别。 相似文献
5.
地表反照率是反映地表能量平衡的重要参数。本文通过中国陆地生态系统通量观测研究网络的实测反照率和MODIS的地表反照率产品对MISR的短波反照率数据进行验证和分析:提取了中国通量网中的8个站点的数据和对应的MODIS、MISR的反照率产品用于验证。验证的结果显示,在多数站点,MISR短波反照率能与地面数据相吻合,大部分的反演误差都集中在0.04以内;MISR与MODIS短波反照率的吻合度更高,总体的误差为0.018,均方根误差在0.04左右。总的来说,MISR地表反照率产品具有较高的反演质量。 相似文献
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7.
中国中东部MODIS与MISR气溶胶光学厚度的对比 总被引：5，自引：2，他引：3
Terra/MODIS前一版本C4和最新版本C5的气溶胶光学厚度(AOT Aerosol OpticalThickness)数据,以及搭载于同一卫星上的Terra/MISR气溶胶光学厚度数据,在中国中东部地区存在差异。本文利用AERONET气溶胶光学厚度数据对以上三种资料验证的结果表明:MODIS气溶胶算法改进之后得到的C5 AOT数据较C4精度确有很大提高,且优于MISR的AOT数据。 相似文献
8.
针对现在缺少对风云二号E星云导风资料的详细对比评估,结合多角度成像仪与风云二号E星云导风的特性,提出了将二者云导风资料的交叉对比方法,利用多角度成像仪云导风资料的优势特征作为对比参照,对2010以及2011年的风云二号E星云导风资料进行参照对比,分析风云二号E星云导风资料的特性。选择2010、2011年1～8月的风云二号E星资料分别与多角度成像仪云导风资料进行分析,对两种资料进行匹配处理,并对匹配结果进行准确的统计分析,便于分析风云二号E星云导风资料的优缺点以及质量变化。研究结果表明:风云二号E星云导风资料的整体质量要稍差于多角度成像仪云导风资料;但是就风云二号E星云导风资料自身而言,2011年的资料质量较2010年有不同程度的提高。 相似文献
9.
Ralph A.KAHN 《中国科学D辑(英文版)》2009,52(1):132-144
The Multiangle Imaging SpectroRadiometer (MISR) launched by NASA in late 1999 has a unique multiangle design, which points
nine cameras at fixed angles along the satellite flight track and collects reflected solar radiation simultaneously. This
design allows the retrieval of a rich dataset of particle abundance, shape and composition over both land and ocean. Some
of its capabilities have not been seen by any currently operating satellite aerosol sensors. Since MISR is sensitive to fine
particles, it provides a new data source to study the spatial and temporal characteristics of air quality over large geographical
regions. We first briefly introduce the MISR instrument, the retrieval and structure of MISR aerosol data, and then review
the applications of MISR aerosol data in various aspects of air quality research since its launch. These include the spatial
distributions of particle pollution events such as dust storms, wild fires, and urban pollution. Because of the high quality
of MISR aerosol data, they can be used as quantitative indicators of particle pollution levels. We review the current modeling
studies of surface level particle concentrations. Next, we introduce research results using MISR’s advanced data such as the
plume heights, and particle microphysical properties. In the discussion, we compare MISR research with current MODIS research
to the best of our ability as MODIS data have been more extensively explored by the Chinese scientific community. Finally,
we summarize the advantages and disadvantages of MISR data related to its applications to the air quality research. Given
the highly quantitative measurements and comprehensive aerosol information MISR can provide, we believe that it will provide
great values to advance our understanding of the particle air pollution in China.
Supported by Harvard-EPA Center on Particle Health Effects (Grant Nos. R-827353 and R-832416), NASA’s Climate and Radiation
Research and Analysis Program, the EOS-MISR Instrument Project and the National High Technology Research and Development Program
of China (Grant No. 2006AA06A305). 相似文献
10.
LI Jian CHEN Shengbo QIN Wenhan Mike MUREFU WANG Yufei YU Yan ZHEN Zhijun 《中国地理科学(英文版)》2019,(4):679-688
The Multi-angle imaging spectroradiometer(MISR) land-surface(LS) bidirectional reflectance factor(BRF) product(MILS_BRF) has unique semi-simultaneous multi-angle sampling and global coverage. However, unlike on-satellite observations, the spatio-temporal characteristics of MILS_BRF data have rarely been explicitly and comprehensively analysed. Results from 5-yr(2011–2015) of MILS_BRF dataset from a typical region in central Northeast Asia as the study area showed that the monthly area coverage as well as MILS_BRF data quantity varies significantly, from the highest in October(99.05%) through median in June/July(78.09%/75.21%) to lowest in January(18.97%), and a large data-vacant area exists in the study area during four consecutive winter months(December through March). The data-vacant area is mainly composed of crop lands and cropland/natural vegetation mosaic. The amount of data within the principal plane(PP)±30°(nPP) or cross PP ±30°(nCP), varies intra-annually with significant differences from different view zeniths or forward/backward scattering directions. For example, multiple off-nadir cameras have nPP but no nCP data for up to six months(September through February), with the opposite occurring in June and July. This study provides explicit and comprehensive information about the spatio-temporal characteristics of product coverage and observation geometry of MILS_BRF in the study area. Results provide required user reference information for MILS_BRF to evaluate performance of BRDF models or to compare with other satellite-derived BRF or albedo products. Comparing this final product to on-satellite observations, what was found here reveals a new perspective on product spatial coverage and observation geometry for multi-angle remote sensing. 相似文献