SORCE Total Solar Irradiance

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The SORCE Mission Page

These measurements are made by the LASP Total Irradiance Monitor (TIM) instrument aboard the SORCE spacecraft. TIM has been measuring total solar irradiance (TSI, W/m^2) since shortly after the SORCE launch in early 2003. This data set contains daily averaged TSI.

The total solar irradiance (TSI) measurement monitors changes in incident sunlight to the Earth's atmosphere. The TIM measures TSI to an estimated absolute accuracy of 350 ppm, 0.035%. Relative changes in solar irradiance are measured to less than 10 ppm/yr (0.001%/yr), allowing determination of possible long-term variations in the Sun's output.

The Solar Radiation and Climate Experiment (SORCE) is a NASA-sponsored satellite mission that is providing state-of-the-art measurements of incoming x-ray, ultraviolet, visible, near-infrared, and total solar radiation. The measurements provided by SORCE specifically address long-term climate change, natural variability and enhanced climate prediction, and atmospheric ozone and UV-B radiation. These measurements are critical to studies of the Sun; its effect on our Earth system; and its influence on humankind.


Units: watts/meter^2

Time range: February 25, 2003 through 7 days prior to today

Update schedule: daily

Dataset volume: The LASP ascii (la) representation of this dataset is about 150 bytes per day


If you use this dataset please cite the following in any resulting publications:

Woods, Thomas; Martin Snow, 2010, "SORCE Total Spectral Irradiance", version,


Kopp, G. and Lean, J.L., "A New, Lower Value of Total Solar Irradiance: Evidence and Climate Significance," Geophys. Res. Letters Frontier article, Vol. 38, L01706, doi:10.1029/2010GL045777, 2011.

Kopp, G., Heuerman, K., Harber, D., and Drake, V., "The TSI Radiometer Facility - Absolute Calibrations for Total Solar Irradiance Instruments", SPIE Proc. 6677-09, 26-28 Aug. 2007.