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Why isn't the solar constant a constant?  

kejun Li   Submitted: 2012-01-05 01:28

In order to probe the mechanism of variations of the Solar Constant on theinter-solar-cycle scale, total solar irradiance (TSI, the so-called SolarConstant) in the time interval of 7 November 1978 to 20 September 2010 isdecomposed into three components through the empirical mode decomposition andtime-frequency analyses. The first component is the rotation signal, countingup to 42.31% of the total variation of TSI, which is understood to be mainlycaused by large magnetic structures, including sunspot groups. The second is anannual-variation signal, counting up to 15.17% of the total variation, theorigin of which is not known at this point in time. Finally, the third is theinter-solar-cycle signal, counting up to 42.52%, which are inferred to becaused by the network magnetic elements in quiet regions, whose magnetic fluxranges from (4.27-38.01) imes1019 Mx.

Authors: K. J. Li, W. Feng, J. C. Xu, P. X. Gao, L. H. Yang, H. F. Liang, L. S. Zhan
Projects: None

Publication Status: ApJ (in press)
Last Modified: 2012-01-09 07:29
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Relationship between group sunspot number and Wolf sunspot number  

kejun Li   Submitted: 2010-06-14 17:08

Continuous wavelet transform and cross-wavelet transform have been used to investigate the phase periodicity and synchrony of the monthly mean Wolf (Rz) and group (Rg) sunspot numbers during the period of June 1795 to December 1995. The Schwabe cycle is the only one common period in Rg and Rz, but it is not well-defined in case of cycles 5-7 of Rg and in case of cycles 5 and 6 of Rz. In fact, the Schwabe period is slightly different in Rg and Rz before cycle 12, but from cycle 12 onwards it is almost the same for the two time series. Asynchrony of the two time series is more obviously seen in cycles 5 and 6 than in the following cycles, and usually more obviously seen around the maximum time of a cycle than during the rest of the cycle. Rg is found to fit Rz better in both amplitudes and peak epoch during the minimum time time of a solar cycle than during the maximum time of the cycle, which should be caused by their different definition, and around the maximum time of a cycle, Rg is usually less than Rz. Asynchrony of Rg and Rz should somewhat agree with different sunspot cycle characteristics exhibited by themselves.

Authors: Kejun Li, Hongfei Liang
Projects: None

Publication Status: accepted by AN
Last Modified: 2010-06-15 09:00
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The Phase Shifts of the Paired Wings of Butterfly Diagrams  

kejun Li   Submitted: 2010-06-14 17:05

Sunspot groups observed by Royal Greenwich Observatory/US Air Force/NOAA from May 1874 to November 2008 and the Carte Synoptique solar filaments from March 1919 to December 1989 are used to investigate the relative phase shift of the paired wings of butterfly diagrams of sunspot and filament activities. Latitudinal migration of sunspot groups (or filaments) does asynchronously occur in the northern and southern hemispheres, and there is a relative phase shift between the paired wings of their butterfly diagrams in a cycle, making the paired wings spatially asymmetrical on the solar equator. It is inferred that hemispherical solar activity strength should evolve in a similar way within the paired wings of a butterfly diagram in a cycle, making the paired wings just and only keep the phase relationship between the northern and southern hemispherical solar activity strengths, but a relative phase shift between the paired wings of a butterfly diagram should bring about an almost same relative phase shift of hemispheric solar activity strength.

Authors: Kejun Li, Hongfei Liang, Wen Feng
Projects: None

Publication Status: accepted by RAA
Last Modified: 2010-06-15 09:00
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Latitude migration of solar filaments  

kejun Li   Submitted: 2010-02-25 21:22

The Carte Synoptique catalogue of solar filaments from March 1919 to December 1989, corresponding to complete cycles 16 to 21 is utilized to show latitudinal migration of filaments at low latitudes (less than 50 deg), and the latitudinal drift of solar filaments in each hemisphere in each cycle of the time interval is compared with the corresponding drift of sunspot groups. The physical implication behind the latitudinal drift of filaments is explored.

Authors: K.J. Li
Projects: None

Publication Status: accepted by MNRAS
Last Modified: 2010-02-26 08:38
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On long-term solar activity at high latitudes  

kejun Li   Submitted: 2007-01-31 20:44

The interesting characteristics of long-term solar activity at highlatitudesare reported as follows:
(1) two cyclic behaviors, but in anti-phase witheach other, simultaneously exist at high latitudes: the magnetic fluxes inunits of gauss of the line-of-sight magnetic fields at latitudes of 600to 700, possibly representing the amplitude of solar magnetic activityat high latitudes, are in complete anti-phase with solar activity at middleand low latitudes, usually represented by sunspot numbers, however, thenumbers of filaments at latitudes of 600 to 900, possiblyrepresenting the complexity of solar magnetic activity at high latitudes,are strangely in complete anti-phase with the magnetic fluxes;
(2) twolatitude migrations, but in two reverse drift directions with each other,exist in a cycle: a poleward migration drifts from middle latitudes towardthe solar poles at the first half part of a normal cycle, following anequatorward migration found from the solar poles toward middle latitudes atthe other half part of the normal cycle;
(3) polar faculae, a frequentlyobserved phenomenon at high latitudes, are inferred to be more related withthe amplitude than the complexity of solar magnetic activity at highlatitudes, and they are in phase with the magnetic fluxes;
(4) high-latitudeflares, a violent active phenomenon at high latitudes, keep in step withneither the amplitude nor the complexity of solar magnetic activity at highlatitudes, they seemingly occur just around the maximum times of the both.

Authors: K. J. Li, J. Mu, and Q. X. Li
Projects: None

Publication Status: In press
Last Modified: 2007-02-01 09:30
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Abstracts by Author
Why isn't the solar constant a constant?
Relationship between group sunspot number and Wolf sunspot number
The Phase Shifts of the Paired Wings of Butterfly Diagrams
Latitude migration of solar filaments
On long-term solar activity at high latitudes

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