EUV irradiance measurements from SOHO during Cycle 23
Abstract
EUV irradiance variability of the double peak feature of cycle 23 is presented. EUV irradiance measurements are being made from SOHO on a regular basis by the Solar Extreme-Ultra-Violet Monitor (SEM) and the Coronal Diagnostic Spectrometer (CDS). SEM continuously measures the full solar disk absolute photon flux at the prominent and scientifically important He II 304 A line, as well as the absolute integral flux between 1 and 500 A. CDS produces full disk spectra in two bands in the range 307-380 A and 515-632 A. The "Sun as a Star" spectrum has been made roughly once a month starting 25 March 1997 to present. As well as irradiance values, the most recent observations also provide moderate resolution solar images to help quantify the important sources of irradiance variability. The EUV irradiance variability is compared to measurements of total irradiance from VIRGO and other solar cycle indices such as sunspot number, magnetic field measurements, and the 10.7 radio flux.
- Publication:
-
34th COSPAR Scientific Assembly
- Pub Date:
- 2002
- Bibcode:
- 2002cosp...34E..97B