Abstract:
This MODIS 250-meter surface reflectance two-band product is computed from
MODIS level-1B land bands 1 and 2 (centered at 648 nanometers and 858
nanometers, respectively). The product is an estimate of the surface
spectral reflectance for each band as it would be measured at ground
level if there were no atmospheric scattering
... or absorption. A correction
scheme reducing the effects of atmospheric gases, aerosols, and thin
cirrus clouds is applied to all non-cloudy pixels passing level-1B
quality control.
The 8-day product is a composite of the previous 8 daily L2G surface
reflectance products, which maintain the native 250-meter resolution in
bands 1 and 2. The best observations during an 8-day period, as
determined by overall pixel quality, observational coverage, and minimum
500-meter band-3 value, are matched geographically according to corresponding
250-meter pointer files. Quality assurance data for the MOD09Q1 product are
provided at different levels of detail, including at the individual pixel
level, at each band and each resolution level, and at the level of the entire
file.
Data Set Characteristics:
Area: ~10 degrees x 10 degrees lat/long
Image Dimensions: 4800 x 4800 rows/columns
File Size: ~139 MB
Resolution: 250 meters
Projection: Sinusoidal
Data Format: HDF-EOS
Science Data Sets (SDS HDF Layers): 3
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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