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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg

[1.06] Comparison of UV Irradiance Variations during Solar Cycles 21 and 22

F. Varadi, J. M. Pap, D. Parker, R. Ulrich (UCLA), L. Floyd, D. Prinz (NRL), L. Puga, R. Viereck (NOAA Space Environment Center)

The main goal of this paper is to study the UV irradiance variations in the Mg II h amp; k core-to-wing ratio derived from the SUSIM irradiance observations on board the Upper Atmosphere Research Satellite and the SBUV instruments on the Nimbus-7 and NOAA satellites. The SUSIM instrument has been monitoring solar UV irradiance since October 12, 1991. The combined Nimbus-7/SBUV1 and NOAA9/SBUV2 data cover the time interval of November 1978 to present and provide information about the UV irradiance variations for almost two solar cycles. The observed UV irradiance changes are compared to the Magnetic Plage Strength Index (MPSI) and Mt. Wilson Sunspot Index (MWSI) derived from the ground-based observations at the Mt. Wilson Observatory at 525 nm. Previous results show that the linear relationship between UV irradiance and proxy data representing the changing emission of plages and the magnetic network breaks down at the minimum of solar cycle 21. In this paper we examine the variations observed in UV irradiance during the various phases of solar cycles 21 and 22, with emphasis on studying the UV irradiance variability during the two solar minima.

Program listing for Friday