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Excess open solar magnetic flux from satellite data: 1. Analysis of the third perihelion Ulysses pass

Lockwood, M., Owens, M. J. and Rouillard, A. P. (2009) Excess open solar magnetic flux from satellite data: 1. Analysis of the third perihelion Ulysses pass. Journal of Geophysical Research, 114. A11103. ISSN 0148-0227

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To link to this article DOI: 10.1029/2009JA014449

Abstract/Summary

We use the third perihelion pass by the Ulysses spacecraft to illustrate and investigate the “flux excess” effect, whereby open solar flux estimates from spacecraft increase with increasing heliocentric distance. We analyze the potential effects of small-scale structure in the heliospheric field (giving fluctuations in the radial component on timescales smaller than 1 h) and kinematic time-of-flight effects of longitudinal structure in the solar wind flow. We show that the flux excess is explained by neither very small-scale structure (timescales < 1 h) nor by the kinematic “bunching effect” on spacecraft sampling. The observed flux excesses is, however, well explained by the kinematic effect of larger-scale (>1 day) solar wind speed variations on the frozen-in heliospheric field. We show that averaging over an interval T (that is long enough to eliminate structure originating in the heliosphere yet small enough to avoid cancelling opposite polarity radial field that originates from genuine sector structure in the coronal source field) is only an approximately valid way of allowing for these effects and does not adequately explain or account for differences between the streamer belt and the polar coronal holes.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
ID Code:5815
Uncontrolled Keywords:open solar flux; Solar Physics, Astrophysics, and Astronomy: Magnetic fields;Interplanetary Physics: Interplanetary magnetic fields; Corotating streams; Solar Physics, Astrophysics, and Astronomy: Solar and stellar variability;
Publisher:American Geophysical Union

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