Composite Scans are global irradiance spectra provided in comma-separated ASCII format. There are two header rows, followed by solar data:
- Header line 1:
Start Time, End Time, Duration
- Header line 2:
Number of rows of solar data, solar zenith angle, solar azimuth angle
- Line 3 - last line:
Wavelength in nm, spectral irradiance in µW/(cm2 nm), TSI reading (only every 10th row).
- S = site code (A = McMurdo Station; B = Palmer Station; C = South Pole Station)
- D = Scan type (D stands for solar scan)
- YY = Year
- HH = Hour at start of scan
- MM = Minute at start of scan
- DDD = Julian Day
Note that the file format of composite scans has changed since the beginning of network operation. Please consult Operations Reports for details.
TSI stands for "Total Scene Irradiance" sensor. The sensor consists of a filtered photodiode that is an integral part of the system. TSI measurements give an indication of the change of solar irradiance during the duration of a composite scan, for example due to clouds. For more information, see Section 2.1.2 of the Operations Report.