The Nimbus 7 solar total irradiance: A new algorithm for its derivation

摘要: The Nimbus 7 satellite has measured the solar total irradiance from November 1978 to July 1991 (153 months). These measurements are important both in physics and for climate change. To insure that capturing true behavior of Sun, it is essential properties radiometer its changes over time be understood. calibration can viewed as a process removing instrumental influences raw measurements, leaving experimenter with an estimate variability. In this paper changing pointing, zero offsets, stability gain, temperature sensitivity, other platform instruments all examined their effects on considered. Only question relative accuracy (not absolute) examined. resulting derived irradiances compared previous analyses Solar Maximum Mission (SMM) measurements. Compared analyses, newly values higher somewhat less variable than older values. Removal off-axis pointing errors new treatment offsets major reasons changes. SMM agree quite well so long any activity present. When Sun becomes quiet, variability resolution, comparison results breaks down. Between 1980 1988 correlation daily 0.83, 0.62 using previously published satellites. monthly means have 0.90, indicating about 80% longer-term variance common. when satellites were operating without problems, was 0.3155% average. For May 1984 December 1988, 0.3255% higher. Therefore if continues operate properly until period 1 year after launch UARS active cavity monitor (ACRIM), appears differences between 7, ACRIM, ACRIM within few hundredths percent. A self-consistent set several nearly two cycles feasible.