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Variation of the solar magnetic flux spectrum during solar cycle 23  

Chunlan Jin   Submitted: 2013-12-19 23:04

By using the unique database of SOHO/MDI full disk magnetograms from 1996 September to 2011 January, covering the entire solar cycle 23, we analyze the time-variability of the solar magnetic flux spectrum and study the properties of extended minimum of cycle 23. We totally identify 11.5 million magnetic structures. It has been revealed that magnetic features with different magnetic fluxes exhibit different cycle behaviors. The magnetic features with flux larger than 4.0 imes 1019 Mx, which cover solar active regions and strong network features, show exactly the same variation as sunspots; However, the remaining 82% magnetic features which cover the majority of network elements show anti-phase variation with sunspots. We select a criterion that the monthly sunspot number is less than 20 to represent the Sun's low activity status. Then we find the extended minimum of cycle 23 is characterized by the long duration of low activity status, but the magnitude of magnetic flux in this period is not lower than previous cycle. Both the duration of low activity status and the minimum activity level defined by minimum sunspot number show a century period approximately. The extended minimum of cycle 23 shows similarities with solar cycle 11, which preceded the mini-maxima in later solar cycles. This similarity is suggestive that the solar cycles following cycle 23 are likely to have low activity.

Authors: Chunlan Jin & Jingxiu Wang
Projects: None

Publication Status: accepted by JGR
Last Modified: 2013-12-20 14:56
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The Sun's small-scale magnetic elements in Solar Cycle 23  

Chunlan Jin   Submitted: 2011-02-16 20:16

With the unique database from Michelson Doppler Imager aboard the Solar and Heliospheric Observatory in an interval embodying solar cycle 23, the cyclic behavior of solar small-scale magnetic elements is studied. More than 13 million small-scale magnetic elements are selected, and the following results are unclosed. (1) The quiet regions dominated the Sun's magnetic flux for about 8 years in the 12.25 year duration of Cycle 23. They contributed (0.94 - 1.44) x 1023 Mx flux to the Sun from the solar minimum to maximum. The monthly average magnetic flux of the quiet regions is 1.12 times that of active regions in the cycle. (2) The ratio of quiet region flux to that of the total Sun equally characterizes the course of a solar cycle. The 6-month running-average flux ratio of quiet region had been larger than 90.0% for 28 continuous months from July 2007 to October 2009, which characterizes very well the grand solar minima of Cycles 23-24. (3) From the small to large end of the flux spectrum, the variations of numbers and total flux of the network elements show no-correlation, anti-correlation, and correlation with sunspots, respectively. The anti-correlated elements, covering the flux of (2.9 - 32.0) x 1018 Mx, occupies 77.2% of total element number and 37.4% of quiet Sun flux. These results provide insight into reason for anti-correlated variations of small-scale magnetic activity during the solar cycle.

Authors: C. L. Jin, J. X. Wang, Q. Song and H. Zhao
Projects:

Publication Status: Accepted by ApJ
Last Modified: 2011-02-18 07:39
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THE PROPERTIES OF HORIZONTAL MAGNETIC ELEMENTS IN QUIET SOLAR INTRANETWORK  

Chunlan Jin   Submitted: 2009-03-20 03:22

Using the data observed by the Solar Optical Telescope/Spectro-Polarimeter aboard the Hinode satellite, the horizontal and vertical fields are derived from the wavelength-integrated measures of Zeeman-induced linear and circular polarizations. The quiet intranetwork regions are pervaded by horizontal magnetic elements. We categorize the horizontal intranetwork magnetic elements into two types: one is the non-isolated element which is accompanied by the vertical magnetic elements during its evolution; another is the isolated element which is not accompanied by the vertical magnetic elements. Their properties, such as lifetime, size and magnetic flux density, are studied, and the relationships among various magnetic parameters are investigated. We identify 446 horizontal intranetwork magnetic elements, among them 87 elements are isolated and 359 are non-isolated. Quantitative measurements reveal that the isolated elements have relatively weaker horizontal magnetic fields, almost equal size, and shorter lifetime comparing with the non-isolated elements. Most non-isolated horizontal intranetwork magnetic elements are identified to associate with the emergence of Omega-shaped flux loops. A few non-isolated elements seem to indicate scenarios of submergence of Omega loops or emergence of U-like loops. There is a positive correlation between the lifetime and the size for both the isolated and non-isolated HIFs. It is also found that there is also positive correlation between the lifetime and the magnetic flux density for non-isolated HIFs, but no correlation for isolated HIFs. Even though the horizontal elements show lower magnetic flux density, they could carry the total magnetic flux in the order of magnitude close to 1025 Mx to the solar surface each day.

Authors: Chunlan Jin, Jingxiu Wang and Guiping Zhou
Projects: None

Publication Status: ApJ, in press
Last Modified: 2009-03-20 09:15
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Subject will be restored when possible  

Chunlan Jin   Submitted: 2008-09-16 21:19

Observations of the quiet Sun from the Solar Optical Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft reveal the magnetic characteristics of the solar photosphere. By making use of the deep mode observations of three quiet regions, we have statistically studied the vector magnetic fields of solar granulation. More than 2000 normal granules are manually selected to form a sample. It is recognized that some granules are even darker than the mean photosphere in intensity, and there is a linear correlation between intensity and Doppler velocity in granules.
The distributions of longitudinal and transverse apparent magnetic flux densities, Doppler velocity and continuum intensity of granules are obtained, and their unsigned magnetic flux measured. Two approaches are carried out in this study. First we obtained the magnetic properties of granulation by averaging the measurements for all the sampling granules. Secondly, we reconstructed an average granular cell basedon a sub-sample, and obtained the detailed distribution of apparent magnetic flux density within the model granular cell. All the results have been compared with that of inter-granular lanes and a few typical abnormal granules.
Our statistic analysis reveals the following results: (1) The unsigned magnetic flux of individual granule spans the range from 1.1 x 1015 to 3.3 x 1018 Mx with a peak distribution at 1.6 x 1016 Mx; (2) The unsigned longitudinal apparent flux densityof granules ranges from almost zero to 212 Mx cm-2 with a mean longitudinal apparent flux density of 12 Mx cm-2, while the transverse apparent flux density ofgranules ranges from 4 to 218 Mx cm-2 with a mean transverse apparent flux density of 79 Mx cm-2. The longitudinal and transverse apparent magnetic flux densities of granules are positively correlated, and the longitudinal apparent flux density of granules is weaker than the corresponding transverse apparent flux density; (3) The magnetic inclination of granules with respect to the surface that's perpendicular to the line-of-sight falls in the range of 4.8 to 76.7 degrees with a peak distribution at 25 degrees. On average, the magnetic vectors in granules are more vertical than that in the inter-granular lanes; (4)There is a strong preference that both the vertical and horizontal fields on the quiet Sun reside in the inter-granular lanes; (5) The detailed distributions of apparent flux density, Doppler velocity, and continuum intensity within an average granular cell are presented. These distributions can well be empirically formulated.

Authors: Chunlan Jin, Jingxiu Wang, and Meng Zhao
Projects:

Publication Status:
Last Modified: 0000-00-00 00:00
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Vector Magnetic Fields of Solar Granulation  

Chunlan Jin   Submitted: 2008-09-16 21:19

Observations of the quiet Sun from the Solar Optical Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft reveal the magnetic characteristics of the solar photosphere. By making use of the deep mode observations of three quiet regions, we have statistically s tudied the vector magnetic fields of solar granulation. More than 2000 normal granules are manually selected to form a sample. It is recognized that some granules are even darker than the mean photosphere in intensity, and there is a linear correlation between intensity and Doppler velocity in granules.

The distributions of longitudinal and transverse apparent magnetic flux densities, Doppler velocity and continuum intensity of granules are obtained, and their unsigned magnetic flux measured. Two approaches are carried out in this study. First we obtained the magnetic properties of granulation by averaging the measurements for all the sampling granules. Secondly, we reconstructed an average granular cell based on a sub-sample, and obtained the detailed distribution of apparent magnetic flux density within the model granular cell. All the results have been compared with that of inter-granular lanes and a few typical abnormal granules.

Our statistic analysis reveals the following results: (1) The unsigned magnetic flux of individual granule spans the range from 1.1 x 1015 to 3.3 x 1018 Mx with a peak distribution at 1.6 x 1016 Mx; (2) The unsigned longitudinal apparent flux density of granules ranges from almost zero to 212 Mx cm-2 with a mean longitudinal apparent flux density of 12 Mx cm-2, while the transverse apparent flux density of granules ranges from 4 to 218 Mx cm-2 with a mean transverse apparent flux density of 79 Mx cm-2. The longitudinal and transverse apparent magnetic flux densities of granules are positively correlated, and the longitudinal apparent flux density of granules is weaker than the corresponding transverse apparent flux density; (3) The magnetic inclination of granules with respect to the surface that's perpendicular to the line-of-sight falls in the range of 4.8 to 76.7 degrees with a peak distribution at 25 degrees. On average, the magnetic vectors in granules are more vertical than that in the inter-granular lanes; (4) There is a strong preference that both the vertical and horizontal fields on the quiet Sun reside in the inter-granular lanes; (5) The detailed distributions of apparent flux density, Doppler velocity, and continuum intensity within an average granular cell are presented. These distributions can well be empirically formulated.

Authors: Chunlan Jin, Jingxiu Wang, and Meng Zhao
Projects: Hinode/SOT

Publication Status: ApJ Submitted
Last Modified: 2008-09-16 21:23
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Subject will be restored when possible  

Chunlan Jin   Submitted: 2008-09-04 20:34

Observations of quiet Sun from the Solar Optical Telescope/Spectro-Polarimeter (SOT/SP) aboard the emph{Hinode} spacecraft would reveal the magnetic characters of the solar photosphere. By making use of the deep mode observations of three quiet regions, we have statistically studied the vector magnetic fields of solar granulation. More than 2000 normal granules are manually selected to form a sample. It is recognized that some granules are even darker than the mean photosphere in intensity, and there is a linear correlation between intensity and Doppler velocity in granules. The distributions of longitudinal and transverse apparent magnetic flux densities, Doppler velocity and continuum intensity of granules are obtained, and their unsigned magnetic flux measured. Two approaches are carried out in this study. First we obtained the magnetic properties of granulation by averaging the measurements for all the sampling granules. Secondly, we reconstructed an average granular cell based on a sub-sample, and obtained the detailed distribution of apparent magnetic flux density within the model granular cell. All the results have been compared with that of inter-granular lanes and a few typical abnormal granules. Our statistic analysis reveals the following results: (1) The unsigned magnetic flux of individual granule spans the range from 1.1 imes 1015 Mx to 3.3 imes 1018 Mx with a peak distribution at 1.6 imes 1016 Mx; (2) The unsigned longitudinal apparent flux density of granules ranges from almost zero to 212 Mx cm-2 with a mean longitudinal apparent flux density of 12 Mx cm-2, while the transverse apparent flux density of granules ranges from 4 to 218 Mx cm-2 with a mean transverse apparent flux density of 79 Mx cm-2. The longitudinal and transverse apparent magnetic flux densities of granules are positively correlated, and the longitudinal apparent flux density of granules is weaker than the corresponding transverse apparent flux density; (3) The magnetic inclination of granules with respect to the surface that's perpendicular to the line-of-sight falls in the range of 4.8 to 76.7 degrees with a peak distribution at 25 degrees. On average, the magnetic vectors in granules are more vertical than that in the inter-granular lanes; (4) There is a strong preference that both the vertical and horizontal fields on the quiet Sun reside in the inter-granular lanes; (5) The detailed distributions of apparent flux density, Doppler velocity, and continuum intensity within an average granular cell are presented. These distributions can well be empirically formulated.

Authors: Chunlan Jin, Jingxiu Wang, and Meng Zhao
Projects: None

Publication Status: accepted
Last Modified: 2008-09-05 08:30
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Abstracts by Author
Variation of the solar magnetic flux spectrum during solar cycle 23
The Sun's small-scale magnetic elements in Solar Cycle 23
THE PROPERTIES OF HORIZONTAL MAGNETIC ELEMENTS IN QUIET SOLAR INTRANETWORK
Subject will be restored when possible
Vector Magnetic Fields of Solar Granulation
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