SUN'S GLOBAL ASYMMETRIES FROM SOHO/MDI DATA

Clear evidence of the onset of the coming activity cycle is provided by the rising asymmetry in the fine structure of the five 72 day sets of SOHO/MDI oscillation data covering 5/1/96-4/27/97. We propose to use upcoming SOHO/MDI data to track the rising phase of solar activity in the way that has never been done before. We will begin with the second five consecutive 72 day datasets which begin on 4/28/97. We will track the asymmetries in the data to probe the nature of the S un's near surface magnetic field by inverting the splitting data for the structure of the field. We will use these results to distinguish among the various models of the field. The real fields are complicated and critical clues from observations are essential.

A persistent surface asymmetry on the Sun has been apparent throughout the current activity minimum when not too much happens in the Sun's outermost layers. We propose to use the SOHO/MDI splitting data to learn whether the asymmetry reflects local, near-surface properties of indirectly reflects a deeply buried toroidal magnetic field.

The f-mode data in the five sets have also revealed a small, but possibly systematic variation of the Sun's seismic radius. We propose to use the coming f-mode data to track the radius and interpret any changes in it.