Extreme solar cycle variability in strong lines between 200 and 400 NM

Authors: White O.R.¹; Fontenla J.²; Fox P.A.¹

Source: Space Science Reviews, Volume 94, Numbers 1-2, November 2000 , pp. 67-74(8)

Publisher: Springer

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Abstract:

Our study of solar cycle irradiance variability in the UV between 200 and 400 nm requires a detailed knowledge of the composition of the solar spectrum in this wavelength range. We compute the synthetic spectrum from 250 to 300 nm and compare it with ATLAS3 and SOLSTICE observations. Synthetic solar spectra for solar minimum and maximum conditions show large variations in broad, strong UV lines. Strong lines of FeI between 260 nm and 264 nm show increases between 0.4× and 3×in their max/min ratio. Our ``broad lines'' database shows 167 lines with similar properties between 200 nm and 400 nm. Our results raise issues of the importance of such large variability in narrow bands and the difficulty of detection in measurements with spectral resolutions of 1 nm.

Language: English

Document Type: Regular paper

Affiliations: 1: High Altitude Observatory, National Center for Atmospheric Research, Box 3000 Boulder, Colorado 80307 USA 2: 1874 MacCullen Drive, Erie, Colorado 80516 USA

Publication date: 2000-11-01