statisticalpropertiesofbipolarmagneticregions

	statisticalpropertiesofbipolarmagneticregions
	Li Dong
刊名	researchinastronomyandastrophysics
	2017
卷号	17 期号:5 页码:16
ISSN号	1674-4527
英文摘要	Using 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.
语种	英语
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/30234]
专题	中国科学院紫金山天文台
作者单位	中国科学院紫金山天文台
推荐引用方式 GB/T 7714	Li Dong. statisticalpropertiesofbipolarmagneticregions[J]. researchinastronomyandastrophysics,2017,17(5):16.
APA	Li Dong.(2017).statisticalpropertiesofbipolarmagneticregions.researchinastronomyandastrophysics,17(5),16.
MLA	Li Dong."statisticalpropertiesofbipolarmagneticregions".researchinastronomyandastrophysics 17.5(2017):16.