Status of the Total Solar Irradiance Climate Data Record
Greg Kopp [Greg.Kopp@lasp.colorado.edu], Laboratory for Atmospheric and Space
Physics (LASP), University of Colorado, Boulder
Recent efforts by the international total solar irradiance (TSI) instrumentation community
have led to enhanced understandings of instrument sensitivities and the causes of
measurement offsets, resulting in improved accuracy of the TSI data record needed for
discerning solar influences in climate studies. Experiments on the TSI Radiometer Facility
(TRF), the world’s only facility capable of directly comparing a TSI instrument to a NISTcalibrated cryogenic radiometer measuring irradiances at solar power levels in vacuum,
permit not only optical power and irradiance measurement validations, but also diagnostics
of instrument artifacts such as scatter that can lead to erroneously high measurements.
Understanding these instrument artifacts allows for retroactive corrections to flight data and
better estimates of measurement uncertainties. Instrument validations on the TRF have been
performed by ground-based or flight versions of the SORCE/TIM, Glory/TIM,
PICARD/PREMOS, SoHO/VIRGO, and ACRIMSat/ACRIM3. I summarize what these
improved understandings indicate for the 33-year long TSI climate data record and discuss
the future of this critical, uninterrupted record given the recent launch failure of the Glory
spacecraft.