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- Title
Observations and Simulations of the Polar Field Reversals in Cycle 23.
- Authors
Durrant, C. J.; Wilson, P. R.
- Abstract
We have used observations obtained by the National Solar Observatory at Kitt Peak to study the reversals of the polar magnetic fields in Cycle 23. We have compared them with corresponding data obtained by the Mt. Wilson Observatory, when these are available, testing both data sets against the locations of Hα filaments. Because of the unreliability of the data at extreme latitudes and because the apparent time of reversal varies with the degree of smoothing applied to the data, it is difficult to determine precise reversal time in each hemisphere from direct observations. However, we show that it is possible to obtain a better-defined and more precise reversal time using polar maps derived from simulations of the synoptic fields. These indirect values, however, depend critically on the diffusivity used in the simulations. We applied various tests to confirm an empirical value for the diffusivity parameter of about 600 km2 s-1 and hence determined empirical reversal times of CR 1976 in the northern hemisphere and CR 1981 in the south.
- Subjects
ORBITING solar observatories; ORBITING astronomical observatories; SOLAR magnetic fields; SOLAR filaments; NORTHERN sky (Astronomy); SOLAR cycle; SOLAR activity
- Publication
Solar Physics, 2003, Vol 214, Issue 1, p23
- ISSN
0038-0938
- Publication type
Article
- DOI
10.1023/A:1024042918007