Evaluation of national and global LAI products derived from optical remote sensing instruments over Canada

Evaluation of national and global LAI products derived from optical remote sensing instruments over Canada

Leaf area index (LAI) is an important surface variable for monitoring the status of vegetation and as input in a number of ecosystem process models. There are currently several coarse-resolution LAI maps over Canada, including a Canada Centre for Remote Sensing ten-day, 1-km resolution, Canada-wide...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on geoscience and remote sensing 2006-07, Vol.44 (7), p.1872-1884
Main Authors: Abuelgasim, A.A., Fernandes, R.A., Leblanc, S.G.
Format: Article
Language:eng
Subjects:
Correlation
Ecosystems
Forests
In situ measurements
Instruments
leaf area index (LAI)
Moderate Resolution Imaging Spectrometer (MODIS)
MODIS
Optical sensors
Polarization and Directionality of the Earth's Reflectance (POLDER)
Remote monitoring
Remote sensing
Retrieval
Robustness
Spatial resolution
Studies
Systeme Pour l'Observation de la Terre (SPOT) VEGETATION (VGT)
Uncertainty
Vegetation
Vegetation mapping
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Leaf area index (LAI) is an important surface variable for monitoring the status of vegetation and as input in a number of ecosystem process models. There are currently several coarse-resolution LAI maps over Canada, including a Canada Centre for Remote Sensing ten-day, 1-km resolution, Canada-wide product based on SPOT-4 VEGETATION (VGT), a MODIS eight-day, 1-km resolution, global product and a monthly, 7-km resolution, global map produced using POLDER-1. These products are difficult to validate because of their large spatial extent and coarse resolution. In this study we use in situ LAI measurements collected over a wide range of forest types and ecological zones in Canada to derive 30-m resolution reference LAI maps based on robust error-in-measurement regressions to Landsat Enhanced Thematic Mapper Plus vegetation indices. The reference maps and LAI products were aggregated to a coarser resolution (3 km for MODIS and VGT and 7 km for POLDER) before comparison to account for registration errors, and variability in sensor projected point spread functions. Spatially corresponding aggregated pixels with both high-quality reference and coarse scale LAI retrievals were compared. The comparison shows reasonable agreement (biases less than 25% or one LAI) between the VGT and reference LAI. The MODIS LAI product showed weak correlations (R 2
ISSN:0196-2892
1558-0644