Total Irradiance Measurements of ERB, ACRIM I, ACRIM II and ERB-S

This chart shows the total solar irradiance (TSI) data gathered by the Nimbus/ERB, Solar Maximum Mission/ ACRIM I, ERB-S, and UARS/ACRIM II instruments. These instrument measurements demonstrate that the total light energy coming to the earth from the sun is not constant and has an 11 year cycle peak-to-peak. This data also shows the absolute variability between these instruments. The UARS spacecraft was launched in September 1991 and is still flying and gathering TSI data.