Learn More
Passive optical multiangle observations make possible the retrieval of scene structural characteristics that cannot be obtained with, or require fewer underlying assumptions than, single-angle sensors. Retrievable quantities include aerosol amount over a wide variety of surfaces (including bright targets); aerosol microphysical properties such as particle(More)
—This paper assesses the effect of changes in solar zenith angle (SZA) and sensor changes on reflectances in channel 1, channel 2, and normalized difference vegetation index (NDVI) from the advanced very high resolution radiometer (AVHRR) Pathfinder land data set for the period July 1981 through September 1994. First, the effect of changes in SZA on channel(More)
—This paper describes results from prototyping of the moderate resolution imaging spectroradiometer (MODIS) radiative transfer-based synergistic algorithm for the estimation of global leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) absorbed by vegetation using land surface reflectances (LASUR) and Landsat data. The algorithm(More)
Leaf area index (LAI) collected in a needle-leaf forest site near Ruokolahti, Finland, during a field campaign in June 14 – 21, 2000, was used to validate Moderate Resolution Imaging Spectroradiometer (MODIS) LAI algorithm. The field LAI data was first related to 30-m resolution Enhanced Thermal Mapper Plus (ETM+) images using empirical methods to create a(More)
— Knowledge of the directional and hemispherical reflectance properties of natural surfaces, such as soils and vegetation canopies, is essential for classification studies and canopy model inversion. The Multi-angle Imaging SpectroRa-diometer (MISR), an instrument to be launched in 1998 onboard the EOS-AM1 platform, will make global observations of the(More)
—This paper presents empirical and theoretical analyses of spectral hemispherical reflectances and transmit-tances of individual leaves and the entire canopy sampled at two sites representative of equatorial rainforests and temperate coniferous forests. The empirical analysis indicates that some simple algebraic combinations of leaf and canopy spectral(More)
The concept of canopy spectral invariants expresses the observation that simple algebraic combinations of leaf and canopy spectral transmittance and reflectance become wavelength independent and determine a small set of canopy structure specific variables. This set includes the canopy interceptance, the recollision and the escape probabilities. These(More)
Radiation reflected from vegetation canopies exhibits high spatial variation. Satellite-borne sensors measure the mean intensities emanating from heterogeneous vegetated pixels. The theory of radiative transfer in stochastic media provides the most logical linkage between satellite observations and the three-dimensional canopy structure through a closed(More)