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Documenting improvement in leaf area index estimates from MODIS using hemispherical photos for Australian savannas

Sea, William B., Choler, Philippe, Beringer, Jason, Weinmann, Richard, Hutley, Lindsay B. and Leuning, Ray (2011). Documenting improvement in leaf area index estimates from MODIS using hemispherical photos for Australian savannas. Agricultural and Forest Meteorology,151(11):1453-1461.

Document type: Journal Article

IRMA ID 82057923xPUB65
Title Documenting improvement in leaf area index estimates from MODIS using hemispherical photos for Australian savannas
Author Sea, William B.
Choler, Philippe
Beringer, Jason
Weinmann, Richard
Hutley, Lindsay B.
Leuning, Ray
Journal Name Agricultural and Forest Meteorology
Publication Date 2011
Volume Number 151
Issue Number 11
ISSN 0168-1923   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-80052281399
Start Page 1453
End Page 1461
Total Pages 9
Place of Publication Amsterdam
Publisher Elsevier BV
HERDC Category C1 - Journal Article (DIISR)
Abstract This paper compares estimates of Leaf Area Index (LAI) obtained from the MODIS (Moderate Resolution Imaging Spectroradiometer) collections 4.8 (MC4) and 5.0 (MC5) with ground-based measurements taken along a 900km north-south transect through savanna in the Northern Territory, Australia. There was excellent agreement for both the magnitude and timing in the annual variation in LAI from MC5 and biometric estimates at Howard Springs, near Darwin, whereas MC4 overestimated LAI by 1-2m 2m -2 for the first 200 days of the year. Estimates of LAI from MC5 were also compared with those obtained from the analysis of digital hemispherical photographs taken during the dry season (September 2008) based on algorithms that included random and clumped distribution of leaves. Linear regression of LAI from MC5 versus that using the clumping algorithm yielded a slope close to 1 (m=0.98). The regression based on a random distribution of leaves yielded a slope significantly different from 1 (m=1.37), with higher Mean Absolute Error (MAE) and bias compared to the clumped analysis. The intercept for either analysis was not significantly different from zero but inclusion of five additional sites that were visually bare or without green vegetation produced a statistically significant offset of +0.16m 2m -2 by MC5. Overall, our results show considerable improvement of MC5 over MC4 LAI and good agreement between MC5 and ground-based LAI estimates from hemispherical photos incorporating clumping of leaves.
Keywords LAI
Savannas
MODIS validation
Hemispherical photos
DOI http://dx.doi.org/10.1016/j.agrformet.2010.12.006   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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Created: Fri, 17 Jan 2014, 00:50:54 CST