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Retrieval of spruce leaf chlorophyll content from airborne image data using continuum removal and radiative transfer

Citation

Malenovsky, Z and Homolova, L and Zurita-Milla, R and Lukes, P and Kaplan, V and Hanus, J and Gastellu-Etchegorry, J-P and Schaepman, ME, Retrieval of spruce leaf chlorophyll content from airborne image data using continuum removal and radiative transfer, Remote Sensing of Environment, 131 pp. 85-102. ISSN 0034-4257 (2013) [Refereed Article]

Copyright Statement

Copyright 2012 Elsevier.

DOI: doi:10.1016/j.rse.2012.12.015

Abstract

We investigate combined continuum removal and radiative transfer (RT) modeling to retrieve leaf chlorophyll a & b content (Cab) from the AISA Eagle airborne imaging spectrometer data of sub-meter (0.4 m) spatial resolution. Based on coupled PROSPECT-DART RT simulations of a Norway spruce (Picea abies (L.) Karst.) stand, we propose a new Cab sensitive index located between 650 and 720 nm and termed ANCB650720. The performance of ANCB650720 was validated against ground-measured Cab of ten spruce crowns and compared with Cab estimated by a conventional artificial neural network (ANN) trained with continuum removed RT simulations and also by three previously published chlorophyll optical indices: normalized difference between reflectance at 925 and 710 nm (ND925&710), simple reflectance ratio between 750 and 710 nm (SR750/710) and the ratio of TCARI/OSAVI indices. Although all retrieval methods produced visually comparable Cab spatial patterns, the ground validation revealed that the ANCB650720 and ANN retrievals are more accurate than the other three chlorophyll indices (R2=0.72 for both methods). ANCB650720 estimated Cab with an RMSE=2.27 μg cm−2 (relative RRMSE=4.35%) and ANN with an RMSE=2.18 μg cm−2 (RRMSE=4.18%), while SR750/710 with an RMSE=4.16 μg cm−2 (RRMSE=7.97%), ND925&710 with an RMSE=9.07 μg cm−2 (RRMSE=17.38%) and TCARI/OSAVI with an RMSE=12.30 μg cm−2 (RRMSE=23.56%). Also the systematic RMSES was lower than the unsystematic one only for the ANCB650720 and ANN retrievals. Our results indicate that the newly proposed index can provide the same accuracy as ANN except for Cab values below 30 μg cm−2, which are slightly overestimated (RMSE=2.42 μg cm−2). The computationally efficient ANCB650720 retrieval provides accurate high spatial resolution airborne Cab maps, considerable as a suitable reference data for validating satellite-based Cab products.

Item Details

Item Type:Refereed Article
Keywords:chlorophyll retrieval, imaging spectroscopy, continuum removal, radiative transfer, PROSPECT, DART, optical indices, Norway spruce, high spatial resolution, AISA
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Geomorphology and Regolith and Landscape Evolution
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management at Regional or Larger Scales
Author:Malenovsky, Z (Dr Zbynek Malenovsky)
ID Code:86466
Year Published:2013
Web of Science® Times Cited:49
Deposited By:Geography and Environmental Studies
Deposited On:2013-09-17
Last Modified:2014-04-15
Downloads:0

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