34th Solar Physics Division Meeting, June 2003
Session 19 The Changing Solar Interior I
Poster, Wednesday, June 18, 2003, 3:30-5:00pm, Mezzanine

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[19.07] The Rapid Onset of Solar Cycle 23

J. L. R. Saba (Lockheed Martin ATC and NASA/GSFC), G. L. Slater, K. T. Strong (Lockheed Martin ATC)

Within two solar rotations, in August/September 1997, the integrated full-disk X-ray flux (an indicator of coronal heating) seen by the Yohkoh Soft X-ray Telescope jumped from low, solar-minimum conditions to 50 percent of the total flux at solar maximum (reached in year 2000).

During the same period, magnetic data from both the SOHO Michelson Doppler Imager and the National Solar Observatory Vacuum Telescope at Kitt Peak showed factor of 2-3, step-function increases in the strong field (above 25 G) flux in both northern and southern hemispheres, although in the south the increase was a rotation later.

The natures of the new and old cycle regions changed after this step up in solar activity:

a) Before the step, both new and old cycle regions were present. Both types were compact, isolated, and short lived; their numbers were similar and few, with the old cycle regions occurring within 20 degrees of the equator and the new cycle regions appearing at higher latitudes.

b) After the step, no significant old-cycle regions emerged. The new cycle regions were more active and longer lived, and often showed interconnections with each other and with the polar regions.

We discuss these results in the context of current models.

This work is supported by NASA contracts NAG5-10483 (MDI) and NAS8-00119 (SXT).


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