TY  - JOUR
AU  - Yaqian, He
AU  - Yanchen, Bo
AU  - Leilei, Chai
AU  - Xiaolong, Liu
AU  - Aihua, Li
PY  - 2016
DA  - 2016//
TI  - Linking in situ LAI and fine resolution remote sensing data to map reference LAI over cropland and grassland using geostatistical regression method
JO  - International Journal of Applied Earth Observations and Geoinformation
VL  - 50
KW  - Leaf area index;Up-scaling;Geostatistical regression;Reduced major axis;Vegetation index
AB  - Highlights•A geostatistical regression (GR) method for leaf area index up-scaling is proposed.•Performance of GR method is better than reduced major axis method.•Performance of GR method varies among vegetation indices and land cover types.;AbstractLeaf Area Index (LAI) is an important parameter of vegetation structure. A number of moderate resolution LAI products have been produced in urgent need of large scale vegetation monitoring. High resolution LAI reference maps are necessary to validate these LAI products. This study used a geostatistical regression (GR) method to estimate LAI reference maps by linking in situ LAI and Landsat TM/ETM+ and SPOT-HRV data over two cropland and two grassland sites. To explore the discrepancies of employing different vegetation indices (VIs) on estimating LAI reference maps, this study established the GR models for different VIs, including difference vegetation index (DVI), normalized difference vegetation index (NDVI), and ratio vegetation index (RVI). To further assess th...
SN  - 0303-2434
ID  - Yaqian2016
ER  - 
TY  - JOUR
AU  - Wang, Ying
AU  - Xue, Yong
AU  - Li, Yingjie
AU  - Guang, Jie
AU  - Mei, Linlu
AU  - Xu, Hui
AU  - Ai, Jianwen
PY  - 2012
DA  - 2012//
TI  - Prior knowledge-supported aerosol optical depth retrieval over land surfaces at 500 m spatial resolution with MODIS data
JO  - International Journal of Remote Sensing
VL  - 33
IS  - 3
AB  - Aerosol optical depth (AOD) values at a spatial resolution of 500 m were retrieved over terrain areas by applying a time series of Moderate resolution Imaging Spectroradiometer (MODIS) 500 m resolution data in the Heihe region (36–42° N, 97–104° E) of Gansu Province, China; in the Pearl River Delta (18–30° N, 108–122° E), China; and in Beijing (39–41° N, 115–118° E), China. A novel prior knowledge scheme was used in the algorithm that performs cloud screening, simultaneous AOD and surface reflectance retrieval from the MODIS 500 m Level 1B data. This prior knowledge scheme produced a new Ångström exponent α, utilizing a Terra pass time α and an Aqua pass time α to better satisfy the invariant α assumption. The retrieved AOD data were compared with AOD data observed with the ground-based, automatic Sun-tracking photometer CE318 at corresponding bands in the Heihe region and with Aerosol Robotic Network (AERONET) data in the Pearl River Delta and in Beijing. Validation experiments demonstrated the potential of ...
SN  - 0143-1161
ID  - Wang2012
ER  - 
TY  - JOUR
AU  - 刘艳
AU  - 王锦地
AU  - 周红敏
AU  - 薛华柱
PY  - 2010
DA  - 2010//
TI  - 黑河中游试验区不同分辨率LAI数据处理、分析和尺度转换
JO  - 遥感技术与应用
SP  - 805
EP  - 813
VL  - 25
IS  - 06
KW  - 叶面积指数(LAI);泰勒级数展开模型;尺度转换
AB  - 2008年开展的黑河综合遥感联合试验获取了大量野外实测叶面积指数(LAI)数据以及遥感LAI产品。在利用LAI地面点观测数据对遥感影像进行验证或者不同分辨率遥感产品相互比较的过程中存在由于地表异质性引起的尺度效应,导致无法直接进行验证、比较,需要进行尺度转换。以基于泰勒级数展开的尺度转换模型为基础,研究不同源LAI之间的尺度转换方法。包括两部分内容:①以高分辨率影像为辅助数据将地面实测点尺度的LAI转换到中、低分辨率遥感像元尺度;②利用高分辨率影像作为亚像元信息对低分辨率LAI产品进行尺度纠正。结果表明,利用泰勒级数展开模型进行尺度转换是一种简单可行的方法,经尺度转换的地面实测点尺度LAI可用作像元尺度数据比较验证的参考。
SN  - 1004-0323
ID  - 刘艳2010
ER  - 
TY  - JOUR
AU  - 康国婷
AU  - 阎广建
AU  - 任华忠
AU  - 王颢星
AU  - 钱永刚
PY  - 2009
DA  - 2009//
TI  - 田块尺度作物辐射温度获取方法对比研究
JO  - 地球科学进展
SP  - 784
EP  - 792
VL  - 24
IS  - 07
KW  - 田块尺度;辐射温度;热像仪;手持式辐射计;采样方式
AB  - 热像仪的优势在于可以获得组分辐射温度,常用于地面温度同步测量实验中,其数据与植被覆盖度联合还可以得到作物田块尺度的平均辐射温度。以黑河流域进行的星—机—地遥感综合观测试验加密观测——盈科绿洲玉米地的热像仪和手持式红外辐射计温度测量数据为基础对不同采样方式获得的地面辐射温度进行对比。对于热像仪数据:①采用阈值法对热像仪影像中的玉米和土壤背景两组分进行分离,获得了各自辐射温度的平均值;②利用LAB彩色变换法处理同步拍摄的真彩色照片,获得每块玉米样地的植被覆盖度;③最终结合组分温度和植被覆盖度求得地块平均的辐射温度。经过实验对比发现,由热红外图像计算获得的地面平均辐射温度与手持式红外辐射计垂直垄或顺垄条带采样获得的地面平均辐射温度差值较小,基本在±1℃以内,而3种测量方式的最大值、最小值相差较多。还模拟了几种常见尺度下利用手持式红外辐射计进行随机采样时,其采样平均值以不同的置信度处于真实温度±0.5℃之间所对应的采样次数。分析表明,基于点测量的采样方案难以仅利用1~2台手持式红外辐射计实现对田块或更大尺度平均辐射温度的准确测量,高时空采样频率是保障地面辐射温度测量精度的前提,与遥感像元尺度相匹配的地面真实性检验需要进行测量方法和设备的革新。
SN  - 1001-8166
ID  - 康国婷2009
ER  -