10. EXPLOITATION AND EVALUATION OF RETRIEVAL
ALGORITHMS FOR GEOSTATIONARY SATELLITE DATA
PROCESSING
85
The differences between AVHRR and SEVIRI observations are
summarized in Figure 4. LAI changes generate spectral displacements or
“spectral signatures” in the red versus near-infrared spectral space diagram
(Verstraete and Pinty 1996). These displacements can be affected by
perturbing factors such as the presence of aerosols, clouds, or illumination
and observation geometry changes. In particular, AVHRR observations
suffer from angular effect under-sampling that may be emphasized by the
presence of cloud. To illustrate the consequences of these two effects on the
spectral signatures, let’s assume that only one out of the first and last three
days of the simulation period is cloud free. The resulting spectral
ALGORITHMS FOR GEOSTATIONARY SATELLITE DATA
PROCESSING
85
The differences between AVHRR and SEVIRI observations are
summarized in Figure 4. LAI changes generate spectral displacements or
“spectral signatures” in the red versus near-infrared spectral space diagram
(Verstraete and Pinty 1996). These displacements can be affected by
perturbing factors such as the presence of aerosols, clouds, or illumination
and observation geometry changes. In particular, AVHRR observations
suffer from angular effect under-sampling that may be emphasized by the
presence of cloud. To illustrate the consequences of these two effects on the
spectral signatures, let’s assume that only one out of the first and last three
days of the simulation period is cloud free. The resulting spectral