THE GLOBAL SOLAR MAGNETIC FIELD-IDENTIFICATION OF TRAVELING, LONG-LIVED RIPPLES
- Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
We have examined the global structure of the solar magnetic field using data from the Fe I spectral line at 5250.2 A obtained at the 150 foot tower telescope at the Mt. Wilson Observatory. For each point on the solar surface, we find the value of the magnetic field in the meridional plane, B{sub m} , by averaging over all available observations using a cosine weighting method. We have revised our cosine weighting method by now taking into account more fully the highest latitude geometry. We use the annual variation in the latitude of the disk center, b{sub 0}, to deduce the tilt angle of the field relative to the local vertical so that we can find the radial component of the field, B{sub r} , from B{sub m} . We find this tilt angle to be small except for a near-polar zone where a tilt-angle model can reduce the annual variation. The reduced annual variation in the deduced B{sub r} allows us to study dB{sub r} /dt and associated deviations in B{sub r} from a smoothed B{sub r} with a smoothing width of 2.5 yr. These functions make evident the presence of small amplitude (3-5 G) but spatially coherent ripples with a semi-regular periodicity of one to three years. At any given time, the half-wavelength (peak to trough) is between 15 Degree-Sign and 30 Degree-Sign of latitude. These patterns are ubiquitous and in many cases drift from near the equator to the poles over a time period of roughly two years. The drift rate pattern is not compatible with simple advection.
- OSTI ID:
- 22126694
- Journal Information:
- Astrophysical Journal, Vol. 768, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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