Abstract:
The MODIS Global Geolocation Angle (MODGGA) files contain information
on solar illumination and instrument viewing geometry angles. These
data can be used to model the geometric relationship and distance
between the area of the Earth's surface imaged, the sun, and the
sensor. This is often required to perform atmospheric corrections, or
... to convert or calibrate spectral data to known (absolute) radiance or
reflectance units.
MODMGGA files are used as input to higher-level products such as MODIS
Surface Reflectance (MOD09). Geometric information for each sensor
observation is stored on a geolocated grid with Level-2 geophysical
parameters stored as Level-2G (gridded) products. The multiple
observations stored in the L2G grids are examined by the Level-3
processes to extract only the most relevant observations per grid
cell.
Data Set Characteristics:
Area: ~10 degrees x 10 degrees lat/long
Image Dimensions: 1200 x 1200 rows/columns
File Size: ~44 MB
Resolution: 1 kilometer
Projection: Sinusoidal
Processing Level: 2G
Data Format: HDF-EOS
Science Data Sets (SDS HDF Layers): 7
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. 
