Factors affecting data resolution

• resolutions of satellite data for the different channels are valid at the earth's position directly below the satellite. This location on the earth is called the satellite subpoint.
• The satellite footprint is the area currently being scanned by the satellite.  Think of the footprint as being similar to the area being photographed with a camera.

• The size of the footprint gets larger when it is further to the east or west from nadir.  Nadir is the angle of the footprint from the subpoint location.  Accordingly, the resolution gets worse with increasing nadir angle.  Here are the footprint resolutions for GOES and Polar orbiting satellites as a function of nadir angle.
• Decreasing resolution is a function of:
  • Curvature of the earth
  • to a lesser extent, the increasing distance of the footprint from the satellite.
• Data at angles greater than 60° are not very useful