2024-03-28T15:06:11Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/105852016-10-11T07:56:11Zcom_10261_74com_10261_6col_10261_453
http://hdl.handle.net/10261/10585
9759
Needle Chlorophyll Content Estimation: A Comparative Study of PROSPECT and LIBERTY
2004
comunicación de congreso
Moorthy, I.
Miller, John R.
Zarco-Tejada, Pablo J.
Noland, Thomas L.
Chlorophyll
PROSPECT
LIBERTY
Radiative Tranfer Models
Model Inversion
2004
2003 - International Geoscience and Remote Sensing Symposium, IGARSS'03 pp. 1676-1678 vol. 3, Toulouse (France), 21-25/7/2004.
Inversion capabilities of leaf-level radiative transfer
models, PROSPECT and LIBERTY, were evaluated to estimate
needle chlorophyll content from measured needle reflectance and
transmittance spectra. Sensitivity studies, using simulation
results, were conducted on the models’ biophysical parameters to
determine robust inversion approaches. Unlike PROSPECT,
which has only one scattering parameter (N), the LIBERTY
model is comprised of two highly sensitive scattering parameters
(average cell diameter and intercellular air gap), which influence
visible and near infrared spectral characteristics and challenge
usual iterative minimization techniques. Validation of inversion
algorithms were based on Jack Pine (Pinus Banksiana) needles,
collected in forested areas near Sudbury, Ontario, Canada,
between June and September of 2001 for laboratory spectral and
biochemical measurements. Both PROSPECT and LIBERTY
were capable of accurately inverting model-simulated reflectance
and transmittance spectra for needle pigment content. However,
inversions using actual data have proven more challenging. For
PROSPECT, with an empirically determined geometric form
factor to account for needle shape, inversions using measured
spectra yield pigment estimates with an RMSE of 13 ug/cm2 over
a pigment range between 15 and 68 ug/cm2. For LIBERTY,
current efforts focus on effectively accounting for the highly
sensitive model scattering parameters to permit accurate
inversion of measured needle spectra for pigment estimation.
Comparisons of inversion results using both PROSPECT and
LIBERTY, as well as contrasts in the sensitivity of specific model
parameters to retrieval accuracy are presented. Such assessments
of leaf-model inversion capabilities are necessary prior to
coupling it with canopy models to make stand level pigment
estimations.
openAccess