Vigorous vegetation growth in the Southern United States after heavy rains
fell during April and early May, 2004, is quantified in these images and
data products from the Multi-angle Imaging SpectroRadiometer (MISR). The
images were acquired on April 1 (top set) and May 3 (bottom set), and
extend through Kansas and Missouri, Oklahoma and Arkansas, and eastern
Texas, with the Texas-Louisiana border at the bottom right-hand corner.
The left-hand images are natural-color views from MISR's nadir camera. In
the month between the April and May images, the overall greenness is
enhanced, and the Boston and Ouachita Mountains are transformed from
brownish hues to vivid green. The city of Dallas, Texas, appears as the
pale gray area at lower left and the Red River (which corresponds with the
Texas-Oklahoma border) is apparent as the yellowish feature flowing toward
the lower left-hand edge. Scattered clouds appear in the upper right-hand
corners of both images. Quantitative values for the vegetation changes are
provided by the center and right-hand images. The middle panels show Leaf
Area Index (LAI), or the area of leaves per unit area of ground below them,
as measured from above. The right-hand panels show FPAR, which is the
fraction of the photosynthetically active region (PAR) of visible light
(400 - 700 nm) absorbed by green vegetation. LAI and FPAR are two important
quantities for monitoring the photosynthetic activity and carbon uptake
efficiency of live vegetation. MISR's LAI and FPAR products make use of
aerosol retrievals to correct for atmospheric scattering and absorption
effects, and use plant canopy structural models to determine the
partitioning of solar radiation. Both of these aspects are facilitated by
the multiangular nature of the MISR measurements.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth
continuously and every 9 days views the entire globe between 82 degrees
north and 82 degrees south latitude. These data products were generated
from a portion of the imagery acquired during Terra orbits 22810 and 23276.
The panels cover an area of about 380 kilometers x 704 kilometers, and
utilize data from blocks 61 to 65 within World Reference System-2 path 26.
MISR was built and is managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra
satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD.
JPL is a division of the California Institute of Technology.