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Multiscale analysis and validation of the MODIS LAI product
BibTeX
@MISC{Strategy_multiscaleanalysis,
author = {Ii Sampling Strategy and Yuhong Tian A and Curtis E. Woodcock A and Yujie Wang A and Jeff L. Privette C and Nikolay V. Shabanov A and Liming Zhou B and Yu Zhang A and Wolfgang Buermann A and Jiarui Dong A and Brita Veikkanen D and Tuomas Häme D and Kaj Andersson D and Mutlu Ozdogan A and Yuri Knyazikhin A and Ranga B. Myneni A},
title = {Multiscale analysis and validation of the MODIS LAI product},
year = {}
}
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Abstract
The development of appropriate ground-based validation techniques is critical to assessing uncertainties associated with satellite databased products. In this paper, the second of a two-part series, we present a method for validation of the Moderate Resolution Imaging Spectroradiometer Leaf Area Index (MODIS LAI) product with emphasis on the sampling strategy for field data collection. Using a hierarchical scene model, we divided 30-m resolution LAI and NDVI images from Maun (Botswana), Harvard Forest (USA) and Ruokulahti Forest (Finland) into individual scale images of classes, region and pixel. Isolating the effects associated with different landscape scales through decomposition of semivariograms not only shows the relative contribution of different characteristic scales to the overall variation, but also displays the spatial structure of the different scales within a scene. We find that (1) patterns of variance at the class, region and pixel scale at these sites are different with respect to the dominance in order of the three levels of landscape organization within a scene; (2) the spatial structure of LAI shows similarity across the three sites, that is, ranges of semivariograms from scale of pixel, region and class are less than 1000 m. Knowledge gained from these analyses aids in formulation of sampling strategies for validation of biophysical products derived from moderate resolution sensors such as MODIS. For a homogeneous (within class) site, where the scales of class and region account for most of the spatial variation, a sampling strategy should focus more on using accurate land cover maps and selection of regions. However, for a heterogeneous (within class) site, accurate point measurements and GPS readings are needed.
Keyphrases
multiscale analysis modis lai product spatial structure hierarchical scene model different landscape scale harvard forest individual scale image lai show similarity appropriate ground-based validation technique landscape organization spatial variation relative contribution field data collection accurate point measurement ndvi image overall variation different characteristic scale biophysical product moderate resolution sensor different scale gps reading accurate land cover map 30-m resolution lai modis lai analysis aid ruokulahti forest sampling strategy two-part series region account
