NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
High-resolution observations of the polar magnetic fields of the sunHigh-resolution magnetograms of the solar polar region were used for the study of the polar magnetic field. In contrast to low-resolution magnetograph observations which measure the polar magnetic field averaged over a large area, we focused our efforts on the properties of the small magnetic elements in the polar region. Evolution of the filling factor (the ratio of the area occupied by the magnetic elements to the total area) of these magnetic elements, as well as the average magnetic field strength, were studied during the maximum and declining phase of solar cycle 22, from early 1991 to mid-1993. We found that during the sunspot maximum period, the polar regions were occupied by about equal numbers of positive and negative magnetic elements, with equal average field strength. As the solar cycle progresses toward sunspot minimum, the magnetic field elements in the polar region become predominantly of one polarity. The average magnetic field of the dominant polarity elements also increases with the filling factor. In the meanwhile, both the filling factor and the average field strength of the non-dominant polarity elements decrease. The combined effects of the changing filling factors and average field strength produce the observed evolution of the integrated polar flux over the solar cycle. We compared the evolutionary histories of both filling factor and average field strength, for regions of high (70-80 deg) and low (60-70 deg) latitudes. For the south pole, we found no significant evidence of difference in the time of reversal. However, the low-latitude region of the north pole did reverse polarity much earlier than the high-latitude region. It later showed an oscillatory behavior. We suggest this may be caused by the poleward migration of flux from a large active region in 1989 with highly imbalanced flux.
Document ID
19950042601
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lin, H.
(Big Bear Solar Observatory, Pasadena, CA United States)
Varsik, J.
(Big Bear Solar Observatory, Pasadena, CA United States)
Zirin, H.
(Big Bear Solar Observatory, Pasadena, CA United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1994
Publication Information
Publication: Solar Physics
Volume: 155
Issue: 2
ISSN: 0038-0938
Subject Category
Solar Physics
Accession Number
95A74200
Funding Number(s)
CONTRACT_GRANT: NSF ATM-91-22023
CONTRACT_GRANT: N00014-89-J-1069
CONTRACT_GRANT: NAGW-1972
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available