Total solar irradiance (TSI) is the dominant driver of the global temperature of the Earth. The climate of the Earth is almost completely determined by the balance between the intensity of the solar radiation and the response of the Earth's atmosphere via absorption, reflection, and re-radiation. Changes in either the solar irradiance or the composition of the atmosphere can cause climate change. Solar irradiance is a purely natural phenomenon, while the composition of the atmosphere is influenced by both natural and anthropogenic effects such as the byproducts of modern industrial societies. Over the past century the average temperature at the Earth's surface has increased by approximately 0.5 degree Celsius. Attributing the portions of this increase and the concomitant climate change due to natural events and anthropogenic sources is of primary importance to the establishment of scientifically and economically effective policy.

The continued measurement of the TSI to determine the Sun's direct and indirect effects on Earth's climate, at current state-of-the-art accuracy and without temporal gaps in the dataset, constitutes the solar irradiance requirement for the Glory mission and the objective of the Total Irradiance Monitor (TIM) instrument. It is essential that there be no temporal gaps in the multi-decadal measurement record of the TSI, as any measured changes in the atmospheric temperature must be appropriately interpreted in the context of solar irradiance variations.

The Glory/TIM continues what will be, at the time of launch in Dec. 2008, an uninterrupted 30-year record of TSI measurements. This instrument is a rebuild of the successful SORCE/TIM launched in early 2003.

+ Go to SORCE/TIM Website

• Greg Kopp, TIM Instrument Scientist
  Laboratory for Atmospheric and Space Physics
  1234 Innovation Drive
  Boulder, Colorado 80303-7814
  Phone: (303) 735-0934
  E-mail: Greg.Kopp@lasp.colorado.edu

• Claus Fröhlich
• Judith Lean
• Joe Rice
• Rodney Viereck
• Dick White

Kopp, G., and G. Lawrence, 2005. The Total Irradiance Monitor (TIM): Instrument design. Solar Phys. 230, 91-109. (Download PDF, document size 1 MB)

Kopp, G., K. Heuerman, and G. Lawrence, 2005. The Total Irradiance Monitor (TIM): Instrument calibration. Solar Phys. 230, 111-127. (Download PDF, document size 2.4 MB)

Kopp, G., G. Lawrence, and G. Rottman, 2005. The Total Irradiance Monitor (TIM): Science results. Solar Phys. 230, 129-139. (Download PDF, document size 1.7 MB)

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