What is the meaning of "total solar irradiance"(TSI)?

Sofie

total solar irradiance—(Abbreviated TSI.) The amount of solar radiation received outside the earth's atmosphere on a surface normal to the incident radiation, and at the earth's mean distance from the sun. Reliable measurements of solar radiation can only be made from space and the precise record extends back only to 1978. The generally accepted value is 1368 W m−2 with an accuracy of about 0.2%. Variations of a few tenths of a percent are common, usually associated with the passage of sunspots across the solar disk. The solar cycle variation of TSI is on the order of 0.1%. http://amsglossary.allenpress.com/glossary/search?id=total-solar-irradiance1 Mar 12 07, 6:17 AM

beeaydee

Total solar irradiance is defined as the amount of radiant energy emitted by the Sun over all wavelengths that fall each second on 11 ft2 (1 m2) outside Earth's atmosphere. http://science.enotes.com/earth-science/insolation-total-solar-irradiance Mar 12 07, 6:18 AM