Fe XIV Synoptic Observations as a Predictor for the Time of Solar Maximum in Cycle 24

Abstract:

In 2012 (Am. Geophys. Union Fall Meeting, Abstract SH12A-05) and 2013 (Solar Phys. Online First, DOI 10.1007/s11207-012-0216-1) Altrock discussed the status of Cycle 24 relative to synoptic observations of Fe XIV from Sacramento Peak (http://nsosp.nso.edu/corona). He found that using earlier cycles, in which solar maximum occurred when Fe XIV emission features associated with the classic "Rush to the Poles" reached latitudes 76° ± 2°, the northern hemisphere Fe XIV features predicted a maximum in the north at 2011.6 ± 0.3. This was confirmed by hemispheric sunspot numbers from SIDC (http://www.sidc.be/silso/) and sunspot areas from NASA MSFC (http://solarscience.msfc.nasa.gov/greenwch.shtml). The earlier papers also noted that southern high-latitude Fe XIV emission indicated the possibility of a southern maximum early in 2014. At low latitudes, earlier cycles reached solar maximum when Fe XIV emission features reached latitudes 20° ± 1.7°. In 2013, these features were at 21° and 15° in the north, again indicating that northern maximum had already occurred. In the south, the Fe XIV features were at 24°. Gopalswamy et al. (2012, Ap. J. Let. 750:L42) came to similar conclusions from a study of microwave brightness and prominence eruptions. This paper will extend the previous studies up to 2014 to include the recent extraordinary surge of activity in the southern hemisphere. In particular we will examine in more detail the relationship between hemispheric Fe XIV emission features and both global and hemispheric sunspot numbers to see (i) if the previous studies correctly predicted the times of hemispheric solar maxima and (ii) what we can learn from the inclusion of two more years of data. The observations used herein are the result of a cooperative program of the Air Force Research Laboratory and the National Solar Observatory.