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Forecasting the Maxima of Solar Cycle 24 with Coronal Fe XIV Emission  

Richard Altrock   Submitted: 2012-09-12 12:42

The onset of the ''Rush to the Poles'' of polar crown prominences and their associated coronal emission is a harbinger of solar maximum. Altrock (Solar Phys. 216, 343, 2003) showed that the ''Rush'' was well-observed in the Fe XIV corona at the Sacramento Peak site of the National Solar Observatory prior to the maxima of Cycles 21 to 23. The data show that solar maximum in those cycles occurred when the center line of the Rush reached a critical latitude of 76? ? 2?. Furthermore, in the previous three cycles solar maximum occurred when the number of Fe XIV emission regions per day > 0.19 (averaged over 365 days and both hemispheres) first reached latitudes 20? ? 1.7?. Applying the above conclusions to Cycle 24 is difficult due to the unusual nature of this cycle. Cycle 24 displays an intermittent Rush that is only well-defined in the northern hemisphere. In 2009 an initial slope of 4.6?year^-1 was found in the north, compared to an average of 9.4 ? 1.7 ? year^-1 in the previous cycles. An early fit to the Rush would have reached 76? at 2014.6. However, in 2010 the slope increased to 7.5?year^-1 (an increase did not occur in the previous three cycles). Extending that rate to 76? ? 2? indicates that the solar maximum smoothed sunspot number in the northern hemisphere already occurred at 2011.6 ? 0.3. In the southern hemisphere the Rush to the Poles, if it exists, is very poorly defined. A linear fit to several maxima would reach 76? in the south at 2014.2. In 1999, persistent Fe XIV coronal emission known as the ''extended solar cycle'' appeared near 70? in the north and began migrating towards the equator at a rate 40% slower than the previous two solar cycles. However, in 2009 and 2010 an acceleration occurred. Currently the greatest number of emission regions is at 21? in the north and 24? in the south. This indicates that solar maximum is occurring now in the north but not yet in the south.

Authors: Richard C. Altrock
Projects: National Solar Observatory (Sac Peak)

Publication Status: submitted to Solar Physics
Last Modified: 2012-09-13 10:14
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The Extended Solar Cycle Tracked High into the Corona  

Richard Altrock   Submitted: 2012-09-12 10:55

We present observations of the extended solar cycle activity in white-light coronagraphs, and compare them with the more familiar features seen in the Fe XIV green-line corona. We show that the coronal activity zones seen in the emission corona can be tracked high into the corona. The peak latitude of the activity, which occurs near solar maximum, is found to be very similar at all heights. But we find that the equatorward drift of the activity zones is faster at greater heights, and that during the declining phase of the solar cycle, the lower branch of activity (that associated with the current cycle) disappears at about 3 R o. This implies that that during the declining phase of the cycle, the solar wind detected near Earth is likely to be dominated by the next cycle. The so-called ?rush to the poles? is also seen in the higher corona. In the higher corona it is found to start at a similar time but at lower latitudes than in the green-line corona. The structure is found to be similar to that of the equatorward drift.

Authors: S. J. Tappin, R. C. Altrock
Projects: National Solar Observatory (Sac Peak)

Publication Status: accepted for publication in Solar Physics
Last Modified: 2012-09-13 10:54
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Coronal Fe XIV Emission During the Whole Heliosphere Interval Campaign  

Richard Altrock   Submitted: 2011-06-29 15:29

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Richard C. Altrock
Projects: National Solar Observatory (Sac Peak)

Publication Status: Solar Phys., Online First, Feb. 2011, DOI 10.1007/s11207-011-9714-9
Last Modified: 2011-06-30 06:51
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Subject will be restored when possible  

Richard Altrock   Submitted: 2007-10-12 15:15

Torsional Oscillations (TO) were first observed on the surface of the Sun as waves of small deviations from differential rotation, which propagate from high latitudes to the equator over solar-cycle time scales. More recently they have been inferred from observations of solar global oscillations to occur in the convection zone. Long-lived brightenings in the corona have also been observed to propagate from near the poles to the equator over similar time scales. This paper will discuss the relationship between TO as observed on the solar surface and in the convection zone and brightenings in the corona. We find that there is an apparent connection between these two phenomena that extends from the equator to latitudes as high as 70 to 80 degrees. This may imply control of both of these phenomena by the driver of the solar cycle (the solar dynamo) and thus place observational constraints on dynamo models.

Authors: Richard Altrock, Rachel Howe and Roger Ulrich
Projects: GONG, Mount Wilson Observatory, National Solar Observatory (Sac Peak)

Publication Status: In Press in Proceedings of the 24th NSO Workshop, Subsurface and Atmospheric Influences on Solar Activity
Last Modified: 2007-10-12 21:07
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Subject will be restored when possible  

Richard Altrock   Submitted: 2007-10-12 15:13

Torsional Oscillations (TO) were first observed on the surface of the Sun as waves of small deviations from differential rotation, which propagate from high latitudes to the equator over solar-cycle time scales. More recently they have been inferred from observations of solar global oscillations to occur in the convection zone. Long-lived brightenings in the corona have also been observed to propagate from near the poles to the equator over similar time scales. This paper will discuss the relationship between TO as observed on the solar surface and in the convection zone and brightenings in the corona. We find that there is an apparent connection between these two phenomena that extends from the equator to latitudes as high as 70◦ to 80◦. This may imply control of both of these phenomena by the driver of the solar cycle (the solar dynamo) and thus place observational constraints on dynamo models.

Authors: Richard Altrock, Rachel Howe and Roger Ulrich
Projects: GONG

Publication Status: In Press in Proceedings of the 24th NSO Workshop, Subsurface and Atmospheric Influences on Solar Activity
Last Modified: 2007-10-12 15:13
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Solar Torsional Oscillations and Their Relationship to Coronal Activity  

Richard Altrock   Submitted: 2007-10-12 15:13

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Richard Altrock, Rachel Howe and Roger Ulrich
Projects: GONG,National Solar Observatory (Sac Peak)

Publication Status: ASP Conference Proceedings, vol.383, pp. 335-342, 2008, Proceedings of the 24th NSO Workshop, Subsurface and Atmospheric Influences on Solar Activity
Last Modified: 2012-01-11 14:26
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Abstracts by Author
Forecasting the Maxima of Solar Cycle 24 with Coronal Fe XIV Emission
The Extended Solar Cycle Tracked High into the Corona
Coronal Fe XIV Emission During the Whole Heliosphere Interval Campaign
Subject will be restored when possible
Subject will be restored when possible
Solar Torsional Oscillations and Their Relationship to Coronal Activity

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