THE GLOBAL AUGUST 11, 1999 ECLIPSE CORONA AND SOLAR CYCLE VARIATIONS

摘要

Qualitative results from the last solar total eclipse (August 11th, 1999) are presented in order to extract some quantitative parameters permitting to discuss the structure of the near-maximum corona and insert the results among what is known of the changing with the solar cycle of activity structure. The collaborative study of the Solar Corona has been performed in Iran, using a radial gradient filter in white light and other techniques. From the eclipse-processed pictures, a structural drawing was analysed to give the distribution of streamlines over the entire corona, in order to look at the deviations from the local radial direction of identified coronal streamers. From the deduced parameter and the known solar cycle variations of this instantaneous "average deviation" of coronal streamers, as deduced from eclipse observations of 4 preceding cycles, we correctly predicted the moment of the following maximum of activity. We further discuss the method, using the "average deviations" measured in 1996-2001 from the Lasco C2 coronagraph processed images (from NRL) of SoHO and found an excellent agreement with the parameters deduced from the last total eclipses of 1998, 1999 and 2001. We believe that "average deviations" are a good parameter to contribute in the understanding of the origin of solar cycle variations of the solar wind and of the magnetic field.