Abstract:
The Earth Science Enterprise is a mission-based NASA initiative designed to
provide data from a series of Earth Observing System (EOS) satellites. These
data may be used to evaluate Earth-related processes and changes in the
environment. In December 1999, NASA launched its Terra satellite into a polar,
Sun-synchronous, 705-kilometer orbit with a
... morning equatorial crossing time.
Multiple sensors flown aboard Terra, include the Moderate-Resolution Imaging
Spectroradiometer (MODIS) instrument. Employing a conventional imaging
spectroradiometer concept, the MODIS instrument is designed to measure
biological and physical processes on a global basis, resulting in a variety of
MODIS products.
This MODIS surface reflectance product is computed from MODIS level-1B land
bands and provides an estimate of the surface spectral reflectance for these
bands as they would have been measured at ground level if there had been no
atmospheric scattering or absorption. These level-3 data cover the Earth's land
surfaces at 500-meter spatial resolution for bands 1 through 7, centered at 648
nanometers, 858 nanometers, 470 nanometers, 555 nanometers, 1,240 nanometers,
1,640 nanometers, and 2,130 nanometers, respectively. Corrections were made to
these daytime data to accommodate for the effects of atmospheric gases,
aerosol, and cirrus clouds.
These MOD09A1 data are provided every 8 days as a gridded level-3 product in
the Integerized Sinusoidal projection. This MODIS surface reflectance product
may be used to generate land-related products or used as input to global and
regional climate models and surface energy balance models. These data also
may be used for land cover characterization.
Data Set Characteristics:
Area: 10 degrees x 10 degrees lat/long
Image Dimensions: 2400 x 2400 rows/columns
File Size: 50-500 MB
Resolution: 500 meters
Projection: Sinusoidal
Data Format: HDF-EOS
Science Data Sets (SDS HDF Layers): 12
Version-4 MODIS/Terra data are validated products.
NOTE: These products are validated, meaning that product uncertainties are
well defined over a range of representative conditions. Although there may be
later improved versions, these data are ready for use in scientific
publications still experimental in nature upon their initial release.
Investigations are underway to assess the scientific validity of these
products. 
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