We have determined both the size of the area that contributes to the solar irradiance increase around an active region and the angular distribution of the radiance excess in it, using data obtained during about one year around solar minimum (April 1996 - April 1997). During the solar minimum and the early raising phase of the new maximum it is possible to study the effect of isolated active regions while there are few of them. The result of this study will be important to separate the contribution of the active regions to the solar irradiance change during the solar cycle from any underlying long term effect, if there is one. The solar radiance measured by the Low-resolution Oscillations Imager (LOI) of the VIRGO instrument and by the MDI instrument aboard SOHO is used to determine the dimension of the radiating area. The increase in irradance is determined by the Sun Photometers (SPM) and Radiometers on the VIRGO instrument.
AAS/Solar Physics Division Meeting #28
- Pub Date:
- May 1997