Dynamics of the Photospheric Magnetic Field in the Vicinity of the Solar Equator

作者：Obridko V N^*; Chertoprud V E

来源：Astronomy Reports, 2012, 56(2): 146-152.

DOI：10.1134/S1063772912010076

SOHO-MDI daily magnetic field synoptic data (a 14-year series of daily maps of the solar magnetic field intensity B available at the site http://soi.stanford.edu/magnetic/index5.html) have been used to analyze the dynamics of the photospheric magnetic field in the vicinity of the solar equator. The standard deviation s(B) of the field B calculated over areas of tens of square degrees on the solar disk was taken as a basic index. An 11-year variation similar to that observed at higher latitudes is observed in the vicinity of the equator, and is similar for weak and strong fields; i.e., the solar cycle exists in the sunspot-free zone. New qualitative data support the idea that the weak background magnetic field increases toward the solar limb. This angular dependence suggests the existence of a transverse component of the background field. The magnetic fields in the vicinity of the equator were significantly different in the initial phases of Cycles 23 and 24. Annual variations of s(B) were observed near the center of the solar disk. These variations are due to two factors: the annual variation of the distance from the equator to the disk center and the increase of s(B) with with distance from the equator. Reliable detection of these variations is an evidence of high accuracy of the s(B) estimates.

• 出版日期2012-2