EUV IRRADIANCE VARIATIONS MEASURED WITH THE SOHO CORONAL DIAGNOSTIC SPECTROMETER OVER 4 YEARS OF SOLAR CYCLE 23

摘要

The Coronal Diagnostic Spectrometer aboard the Solar and Heliospheric Observatory observes the solar EUV spectrum in two bands between 308-379 A and 513-633 A, spanning the temperature range from 3 x 10~4 K to 2.7 x 10~6 K. The full Sun irradiance can be measured by rastering the instrument over the solar disk. Measurements of the solar irradiance have been made starting 25 March 1997 and continue to the present, ranging from near solar minimum to solar maximum. This presentation extends earlier work by combining data from both before and after SOHO's accident in 1998. Comparisons are made between the CDS measurements, and predictions from the Hintereggar, EUVAC, EUV97, and SOLAR2000 models. Until the recent launch of the TIMED satellite, these measurements were the only current EUV spectral irradiance measurements taken on a regular basis. The high spectral resolution of these measurements, combined with the coverage of a significant proportion of the solar cycle, provide a unique dataset for understanding solar variability in the EUV.