GOLF: A New Proxy for Solar Magnetism

Abstract

Solar magnetism is measured with different indices: for instance the Magnetic Plage Solar Index (MPSI) and the Mount Wilson Sunspot Index (MWSI), number of sunspots, radio flux at 10.7 cm, Ca II K, Mg II K, EUV, He I or Lα. Bachmann & White (1994) compared these indicators of the solar activity showing a hysteresis of the solar cycle variations and a time lag between these indices not related to instrumental effects. Later, Ozgüç & Ataç (2001) extended this study of hysteresis phenomenon between flare index and other solar indices (mean magnetic field, coronal index). In its original working configuration, GOLF/SoHO was able to measure the solar mean magnetic field over 26 days (García et al. 1999). We check here if the velocity data could be used as another solar magnetism proxy with the advantage of having a duty cycle ≥95% during the last 12 years. We will compare the GOLF data with some of the above-mentioned solar activity indices.