Space Science Reviews

, Volume 125, Issue 1, pp 39-51

First online:

Measurement of Total and Spectral Solar Irradiance

  • G. RottmanAffiliated withLaboratory for Atmospheric and Space Physics, University of Colorado Email author 

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The Sun’s electromagnetic radiation powers our solar system. In the case of the Earth it heats the lands and ocean, maintains our atmosphere, generates clouds, and cycles water. For other planets and minor bodies, similar and appropriate physical processes occur, also powered by the Sun. The Sun varies on all time scales and a precise knowledge of the Sun's irradiance and its variation is essential to our understanding of environments and physical conditions throughout our solar system. Measurements of solar irradiance and its variation can only be made from space, and almost thirty years of observation have now established that the total solar irradiance (TSI) varies by only 0.1 to 0.3%, while certain portions of the solar spectrum, the ultraviolet for example, vary by orders of magnitude more. This paper provides an overview of TSI observations and of spectral irradiance observations from the ultraviolet to the near infrared.


solar irradiance solar activity cycle climate variability atmospheric photochemistry instruments and techniques