Surfrad versus Boulder
Obviously, the radiation fluxes from Boulder, Surfrad frequently fall below the recommended physical possible limits. To judge the data quality as a whole the measurements were compared with the data from the nearby BSRN station Boulder.
For intercomparison hourly averaged radiation fluxes from both stations were chosen from 1996. A linear regression presented in the figures below indicates an agreement of both datasets within the expected measuring accuracy. This example shows that the interpretation of the results of the recommended physical possible limits must be taken with care.