TMCF PGE: IRRELVDEP

This TMCF PGE calculates the elevation angle dependence of one irradiance measurement sequence. One irradiance measurement sequence in one orbit over one of three diffusers (quartz volume diffuser, regular aluminium diffuser, backup aluminium diffuser) contains 77 light measurements followed by 77 dark / background measurements. During the 77 light measurements (144 seconds) the elevation angle from the sun onto the on-board diffuser is changing from about +4.0 degrees to about -4.0 degrees as a result of the orbital movement of the satellite. The change in elevation angle causes a change in measured irradiance signal. This TMCF PGE investigates this elevation angle dependence.
For the level-1b irradiance product only the quartz volume diffuser is used and the individual measurements in the elevation angle range between -3.0 degrees and +3.0 degrees are first corrected for elevation and azimuth (seasonal) angle dependence and subsequently averaged.