Impact of spatial LAI heterogeneity on estimate of directional gap fraction from SPOT-satellite data
文献类型：SCI/SSCI论文
| 作者 | Ma L. L. ; Li C. R. ; Tang B. H. ; Tang L. L. ; Bi Y. Y. ; Zhou B. Y. ; Li Z. L. |
| 发表日期 | 2008 |
| 关键词 | directional gap probability scaling bias leaf area index clumping index leaf-area index photosynthetically active radiation vegetation temperatures canopy soil foliage retrieval models extinction fife |
| 英文摘要 | Directional gap probability or gap fraction is a basic parameter in the optical remote sensing modeling. Although some approaches have been proposed to estimate this gap probability from remotely sensed measurements, few efforts have been made to investigate the scaling effects of this parameter. This paper analyzes the scaling effect through aggregating the high-resolution directional gap probability (pixel size of 20 meters) estimated from leaf area index (LAI) images of VALERI database by means of Beer's law and introduces an extension of clumping index, (C) over cap, to compensate the scaling bias. The results show that the scaling effect depends on both the surface heterogeneity and the nonlinearity degree of the retrieved function. Analytical expressions for the scaling bias of gap probability and (C) over cap are established in function of the variance of LAI and the mean value of LAI in a coarse pixel. With the VALERI dataset, the study in this paper shows that relative scaling bias of gap probability increases with decreasing spatial resolution for most of land cover types. Large relative biases are found for most of crops sites and a mixed forest site due to their relative large variance of LAI, while very small biases occur over grassland and shrubs sites. As for (C) over cap, it varies slowly in the pure forest, grassland and shrubs sites, while more significantly in crops and mixed forest. |
| 出处 | Sensors |
| 卷 | 8 |
| 期 | 6 |
| 页 | 3767-3779 |
| 收录类别 | SCI |
| 语种 | 英语 |
| ISSN号 | 1424-8220 |
| 源URL | [http://ir.igsnrr.ac.cn/handle/311030/23299]  |
| 专题 | 地理科学与资源研究所_历年回溯文献 |
| 推荐引用方式 GB/T 7714 | Ma L. L.,Li C. R.,Tang B. H.,et al. Impact of spatial LAI heterogeneity on estimate of directional gap fraction from SPOT-satellite data. 2008. |
入库方式： OAI收割
来源：地理科学与资源研究所
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