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Validation of Collection 5 MODIS LAI product by scaling-up method using field measurements

机译：使用现场测量通过放大方法验证Collection 5 MODIS LAI产品

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摘要

Leaf area index (LAI) is very often a critical parameter in process-based models of vegetation canopy response to global environment change. This paper made an assessment of the Collection 5 MODIS LAI product (MCD15A2) using field sample data in cropland areas. One of the major problems for validating MODIS LAI product using field measurements is the scale mismatch between ground "point" measurements and the MODIS resolutions. In heterogeneous areas, we need to transform field measurements to the scale of MODIS due to scale effect caused by the heterogeneity of land surface. In this study, we performed the scale transformation through fractal method. LAI was measured with the LAI-2000 plant canopy analyzer. The LAI-2000 measurements were multiplied by a clumping index to get true LAI values. The field data was related to 30-m resolution TM images using empirical methods to create reference LAI map. Fractal dimensions for each MODIS pixel were calculated using a triangular prism method based on reference LAI map. Then the field LAI values were upscaled to 1km spatial resolution using the fractal dimension theory. The MODIS LAI product validation results shown that, MODIS LAI are lower than the ground measurements without scale effect correction, but quite close to the upscaled field measured LAI. The conclusion is the fractal dimension theory can be used to solve the scale problem caused by spatial heterogeneity in LAI products validation.
机译：在基于过程的植被冠层对全球环境变化的响应的基于模型的模型中，叶面积指数（LAI）通常是关键参数。本文使用农田地区的现场样本数据对Collection 5 MODIS LAI产品（MCD15A2）进行了评估。使用现场测量来验证MODIS LAI产品的主要问题之一是地面“点”测量与MODIS分辨率之间的比例失配。在异质性地区，由于地表异质性引起的尺度效应，我们需要将实地测量转换为MODIS的尺度。在这项研究中，我们通过分形方法进行了尺度转换。使用LAI-2000植物冠层分析仪测量LAI。将LAI-2000的测量值乘以总成指数即可得出真实的LAI值。使用经验方法将现场数据与30米分辨率的TM图像相关，以创建参考LAI图。每个MODIS像素的分形维数是根据参考LAI映射使用三角棱镜方法计算的。然后，使用分形维数理论将现场LAI值提升到1km空间分辨率。 MODIS LAI产品验证结果表明，MODIS LAI低于未进行尺度效应校正的地面测量结果，但与现场实测LAI相当接近。结论是分形维数理论可以用来解决LAI产品验证中空间异质性引起的尺度问题。

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  • 来源
  • 会议地点 Prague(CZ)
  • 作者

    Huazhu Xue; Jindi Wang; Chen Ping;

  • 作者单位

    State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications, CAS,School of Surveying and Land Information Engineering, Henan Polytechnic University,Jiaozuo,454000,China,Research Center for Remote Sensing and GIS, School of Geography, Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, Beijing Normal University, 100875, China;

    State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications, CAS,Research Center for Remote Sensing and GIS, School of Geography, Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, Beijing Normal University, 100875, China;

    State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications, CAS,Research Center for Remote Sensing and GIS, School of Geography, Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, Beijing Normal University, 100875, China;

  • 会议组织
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境遥感;
  • 关键词

    scale-up; fractal dimension; triangular prism; LAI-2000; TM; MCD15A2;

    机译：放大;分形维数三棱镜; LAI-2000； TM值; MCD15A2;

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