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Session 35 - Solar Magnetic Fields.
Display session, Tuesday, June 11
Tripp Commons,

[35.05] Solar-Cycle Variation of Polarity Inversion

H. P. Jones (NASA/GSFC)

Multi-scale polarity inversion maps are constructed from National Solar Observatory/Kitt Peak magnetograms for periods coinciding with those used by Harvey (1993, PhD Thesis, Utrecht University). The motivation for this analysis stems from earlier work on a small sample which suggested that neutral-line "length" varies as a power of the scale used to determine the polarity inversion loci and that only the amplitude, not the exponent, varies between maximum and minimum phases of the solar cycle. Harvey observed similar behavior in the areal distribution of new bipolar regions, and a plausible hypothesis is that neutral line length vs. scale is a mapping of this areal distribution, i.e., an efficient way to count bipoles. Broadly speaking, the behavior of neutral line length vs. scale is confirmed from this more extensive sample; the curves from many days at either minimum or maximum are tightly clustered and are nearly parallel on log-log plots. Emperically, if one represents the areal distribution of new bipolar regions as a function of time and area as \begindisplaymath n(t,A) \sim f(t)g(A), \enddisplaymath then neutral-line length, \ell, varies with scale, s, as \begindisplaymath \ell(s) \sim const*[g(s^2)/f(t)]^r \enddisplaymath where r \simeq 0.2. To explore whether this relation has more than emperical significance, future work is planned to compute neutral line maps from synthesized magnetograms based on the superposition of known, prespecified distributions of dipoles.

Program listing for Tuesday