The level2 daily mean DIARAD Total Solar Irradiance
This is the data as measured by the left channel of the DIARAD radiometer after ageing correction by the right channel.
The daily mean DIARAD Total Solar Irradiance
This is the data as measured by both channels of the DIARAD radiometer.
'left': daily mean left channel measurements - the left channel is measuring continuously 'right': right channel measurements minus 5 W/m2 - the right channel is measuring sporadically for verification of the ageing of the left channel
The DIARAD ageing correction
The operational measurements are made with the DIARAD Left channel. From time to time - roughly every month - measurements are made with the DIARAD Right channel. The difference between the Right and the Left channel measurements, shown below, provides a measurement of the ageing of the Left channel.
'measured' : measured Right minus Left TSI, normalised to zero at the beginning of the mission. 'fit' : running mean of measured points - The DIARAD Left measurements are corrected for ageing by adding this fit.