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Journal of Applied Remote Sensing

Relationships between Moderate Resolution Imaging Spectroradiometer water indexes and tower flux data in an old growth conifer forest
Author(s): Yen-Ben Cheng; Sonia Wharton; Susan L. Ustin; Pablo J. Zarco-Tejada; Matthias Falk; Kyaw Tha Paw U
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Paper Abstract

Methods to accurately estimate the biophysical and biochemical properties of vegetation are a major research objective of remote sensing. We assess the capability of the MODIS satellite sensor to measure canopy water content and evaluate its relationship to ecosystem exchange (NEE) for an evergreen forest canopy. A time-series of three vegetation indexes were derived from MODIS data, the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Water Index (NDWI), and the Normalized Difference Infrared Index (NDII), which were compared to physically based estimates of equivalent water thickness (EWT) from the airborne AVIRIS hyperspectral instrument over a temperate conifer forest in southwestern Washington. After cross-calibration of the imagery, water indexes derived from MODIS showed good agreement with AVIRIS EWT, while the NDVI was insensitive to water content variation. Three years of NEE data from eddy covariance measurements at the Wind River AmeriFlux tower were compared with the time series of MODIS indexes, which show seasonal water content has similar trajectory with NEE. In contrast, the MODIS NDVI time series did not yield a good relationship with NEE. This study demonstrates the potential to use MODIS water indexes for spatial and temporal NEE estimation at regional and global scales in appropriate ecosystems.

Paper Details

Date Published: 1 May 2007
PDF: 26 pages
J. Appl. Remote Sens. 1(1) 013513 doi: 10.1117/1.2747223
Published in: Journal of Applied Remote Sensing Volume 1, Issue 1
Show Author Affiliations
Yen-Ben Cheng, Univ. of California/Davis (United States)
Sonia Wharton, Univ. of California/Davis (United States)
Susan L. Ustin, Univ. of California/Davis (United States)
Pablo J. Zarco-Tejada, Univ. of California/Davis (United States)
Matthias Falk, Univ. of California/Davis (United States)
Kyaw Tha Paw U, Univ. of California/Davis (United States)

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