Summary

The published information on instrumental accuracy has been presented above: it is repeated here for completeness.

For the ERBE solar monitor, the precision and accuracy are estimated to be less than 0.l% and 0.2%, respectively, set by electronic noise and 13-bit digitizing quantization.

For the ERBE scanner instrument, the precision (3) and systematic error bounds, respectively, are estimated as:

         Band                   Uncertainty ()
------------------------        ---------------------
Shortwave (0.2 - 5.0 m)         0.3  and 0.75
Longwave (5.0 - 50.0 m)         0.45 and 0.75
  Total (0.2 - >50 m)           0.3  and 0.5

The actual performance of the instruments over a number of years and the careful, space- relevant calibrations justify confidence in these instruments. Despite the inclusion of features to maintain long-term calibration on the satellite, there is still a possibility that the on-board systems will drift in a manner that cannot be discerned from the ground. Many satellite instruments have suffered from degradation of calibrations over time, especially in the shortwave channels. Methods of verifying satellite instrument calibrations exist and should be a routine part of an integrated scientific program; these methods include the use of high-flying aircraft and clear-sky observations of well-characterized land areas. These issues are discussed in more detail in the section of this report entitled Indirect Calibration.