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Statistical properties of bipolar magnetic regions
Li, Dong
2017-05-01
Source PublicationRESEARCH IN ASTRONOMY AND ASTROPHYSICS
ISSN1674-4527
Volume17Issue:5Pages:16
Corresponding AuthorLi, Dong(lidong@pmo.ac.cn)
AbstractUsing observations from the Michelson Doppler Imager (MDI) onboard Solar and Heliospheric Observatory (SOHO), we develop a computational algorithm to automatically identify bipolar magnetic regions (BMRs) in active regions (ARs), and then study their statistical properties. The individual magnetic (positive or negative) pole of a BMR is determined from the region with an absolute strength above 55G and with an area larger than 250 pixel(2) (similar to 495 Mm(2)), while a BMR is identified as a pair of positive and negative poles with the shortest area-weight distance between them. Based on this method, 2234 BMRs are identified fromMDI synoptic magnetograms between Carrington Rotations 1909 (1996 May 06) and 2104 (2010 December 10). 1005 of them are located in the northern hemisphere, while the other 1229 are in the southern hemisphere. We find that the BMR parameters (e.g., latitude, separation, fragment number and strength) are similar to those of ARs. Moreover, based on the maximum likelihood estimation (MLE) method, the frequency distributions representing the occurrence of these BMRs as functions of area and magnetic flux exhibit a power-law behavior, i.e., dN/d x alpha x (-alpha x), with indices of alpha(A) = 1.98 +/- 0.06 and alpha(F) = 1.93 +/- 0.05 respectively. We also find that their orientation angles (theta) follow "Hale's Polarity Law" and deviate slightly toward the direction of the solar equator. Consistent with previous findings, we obtain the dependence of orientation angles on latitudes for normal BMRs during the 23rd solar cycle. The north-south asymmetry of these BMRs is also detected here.
Keywordmethods: statistical Sun: activity Sun: magnetic fields
DOI10.1088/1674-4527/17/5/40
WOS KeywordACTIVE REGIONS ; FREQUENCY-DISTRIBUTIONS ; SUNSPOT GROUPS ; SOLAR-FLARES ; TILT ANGLES ; FLUX ; FIELDS ; CYCLE ; BURSTS ; SUN
Indexed BySCI
Language英语
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000405574100001
PublisherNATL ASTRONOMICAL OBSERVATORIES, CHIN ACAD SCIENCES
Citation statistics
Document Type期刊论文
Identifierhttp://libir.pmo.ac.cn/handle/332002/22869
Collection中国科学院紫金山天文台
Corresponding AuthorLi, Dong
AffiliationChinese Acad Sci, Key Lab Dark Matter & Space Sci, Purple Mt Observ, Nanjing 210008, Jiangsu, Peoples R China
Recommended Citation
GB/T 7714
Li, Dong. Statistical properties of bipolar magnetic regions[J]. RESEARCH IN ASTRONOMY AND ASTROPHYSICS,2017,17(5):16.
APA Li, Dong.(2017).Statistical properties of bipolar magnetic regions.RESEARCH IN ASTRONOMY AND ASTROPHYSICS,17(5),16.
MLA Li, Dong."Statistical properties of bipolar magnetic regions".RESEARCH IN ASTRONOMY AND ASTROPHYSICS 17.5(2017):16.
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