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Session 2 - Everything Else.
Display session, Friday, June 27
Ballroom C, Chair: Richard Canfield

[2.63] Solar Irradiance Variations due to the Quiet Sun Network

K. P. Topka (SPRC), T. D. Tarbell, A. M. Title (LMATC)

An estimate for the change in total solar irradiance due to quiet sun network during the 11-year solar cycle is presented. The estimate is based on measurements of the center-limb contrast function for quiet sun magnetic elements. These measurements are the result of analysis of near-simultaneous, co-registered, digital, photometric images of the photospheric intensity (4300 - 6300 A) and line-of-sight magnetic field. Images were made with the Lockheed tunable filter instrument at the Swedish Solar Observatory, La Palma, between 1991 and 1994. The result is of order 0.1of the surface of the Sun and thus a very large extrapolation is made, limiting the accuracy of the result.

Measurements made by satellite radiometers indicate that on the time scale of solar activity, the total solar irradiance is greater at activity maximum than at minimum by about 0.1 to 0.15 Our result is consistent with this. Earlier results on active region plage, using similar data from La Palma, indicate that it does does not contribute significantly to long-term solar irradiance variations.

This work has been supported by NSF contract ATM-9320353, by NASA contracts NASW-4612 and NAS8-39747, and by Lockheed IR funds.


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