Critique on the solar rehabilitation procedures used in SOLMET-2

Abstract

A critique of the NOAA procedure for rehabilitation of solar data is given by comparing recent data on clear solar noon atmospheric transmission with the calculated transmissions used in the rehabilitation process. It is found that the standard year irradiance (SYI) method used by NOAA is generally within about 3% of the data except for sites at high latitude in winter. The SYI values are too low at such sites, the worst case being Seattle where winter insolation is underestimated by over 20%. The overall assessment of the NOAA rehabilitation procedures at most sites is that the final result: standard year corrected data provide a reasonable set of consistent values. However, the data at northerly sites are too low.