Solar radiation enters the Earth's atmosphere with a portion being scattered by clouds and aerosols.

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Processing, archiving and distributing Earth science data
at the NASA Langley Research Center

What is the Space Oblique Mercator (SOM) projection?

SOM is a space-based map projection in which the reference meridian nominally follows the spacecraft ground track. It provides a mapping from latitude and longitude to a coordinate system that is approximately aligned with the MISR swath. SOM was used because it minimizes distortion and resampling effects, and permits the greatest flexibility in the choice of Earth-based projections. SOM also allows direct cross-comparison with data from other instruments and simplifies global mapping, since the data have already been geolocated. For more information see the MISR Level 1 Georectification and Registration Algorithm Theoretical Basis Document (ATBD-MISR-03), and also Snyder, J.P., Map Projection - A Working Manual, United States Geological Survey Professional Paper 1395, U.S. Government Printing Office, Washington, DC (1987).

  SOM vs Lat/Lon
  • Terra orbits Earth in a pattern of 233 unique paths.
  • SOM defines a separate projection for each path.
SOM Background. Orbital Paths/Blocks. Example of MISR paths and blocks.