Table C-3. Solar Radiation Source Flags
| Flag | Definition |
| A | Post-1976 measured solar radiation data as received from NCDC or other sources |
| B | Same as 'A' except the global horizontal data underwent a calibration correction |
| C | Pre-1976 measured global horizontal data (direct and diffuse were not measured before
1976), adjusted from solar to local time, usually with a calibration correction |
| D | Data derived from the other two elements of solar radiation using the relation,
Kt = Kn + Kd (see
Part 2, Section 8.1 for more information) |
| E | Modeled solar radiation data using inputs of observed sky cover (cloud amount)
and aerosol optical depths derived from direct normal data collected at the same location |
| F | Modeled solar radiation using interpolated sky cover and aerosol optical depths
derived from direct normal data collected at the same location |
| G | Modeled solar radiation data using observed sky cover and aerosol optical
depths estimated from geographical relationships |
| H | Modeled solar radiation data using interpolated sky cover and estimated
aerosol optical depths |
| ? | Source does not fit any of the above categories. Used for nighttime values, calculated
extraterrestrial values, and missing data |