Spatial validation of the collection 4 MODIS LAI product in eastern Amazonia
Spatial validation of the collection 4 MODIS LAI product in eastern Amazonia
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DOI：
10.1109/tgrs.2005.856632
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发表时间：
2005-10
影响因子：
8.2
通讯作者：
L. Aragão;Y. Shimabukuro;F. Espírito-Santo;M. Williams
中科院分区：
文献类型：
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作者：
L. Aragão;Y. Shimabukuro;F. Espírito-Santo;M. Williams
本文报告了 Collection 4 MODIS 叶面积指数 (LAI) 产品在亚马逊流域东部 Tapajo/spl 急性/s 地区的验证情况。验证站点包含在 MODIS LAI 产品的图块 h12v09 中。评估MODIS LAI精度的方法包括两个主要步骤：（1）基于现场数据和来自增强型专题制图器Plus传感器的遥感信息之间的关系，以及现场数据和来自数字高程模型的地形信息之间的关系，对LAI表面的生成进行多元回归分析； (2)这些LAI表面与MODIS LAI表面的直接比较。分析表明，Tapajo/spl 急性/s 地区的 MODIS LAI 被显着高估了 1.18 倍。未发现 MODIS LAI 与验证表面之间的关系。这些结果表明备份算法在 LAI 检索中占主导地位，该算法在饱和域过度补偿了 LAI 值。土地覆盖层 (MOD12Q1) 的过度概括可能是查找表参数化的不确定性来源。必须在亚马逊地区开展进一步的验证工作，对 MODIS LAI 表面进行定量质量评估，以提高其准确性。
This paper reports on the validation of the Collection 4 MODIS leaf area index (LAI) product over the Tapajo/spl acute/s region, eastern Amazonia. The validation site is enclosed in tile h12v09 of the MODIS LAI product. The methodology to assess MODIS LAI accuracy included two main steps: (1) a multiple regression analysis for the generation of LAI surfaces, based on the relationships between field data and remote sensing information from the Enhanced Thematic Mapper Plus sensor, and between field data and topographic information from a digital elevation model; (2) the direct comparison of these LAI surfaces with the MODIS LAI surfaces. The analysis indicated that MODIS LAI is significantly overestimated for the Tapajo/spl acute/s region by a factor of 1.18. No relationships between MODIS LAI and the validation surfaces were found. These results are indicative of a predominance of LAI retrievals by the backup algorithm, which is overcompensating LAI values at the saturation domain. The overgeneralization of the land cover layer (MOD12Q1) can be a source of uncertainties for the lookup table parameterization. Further validation efforts must be carried out over Amazonia for a quantitative quality assessment of the MODIS LAI surfaces in order to improve its accuracy.