A Comparison of Co-temporal Vector Magnetograms Obtained with HMI/SDO and SP/Hinode

作     者：Mei Zhang Haocheng Zhang Chengqing Jiang Mei Zhang;Haocheng Zhang;Chengqing Jiang

作者机构：National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space SciencesUniversity of Chinese Academy of SciencesBeijing 100049China High Altitude ObservatoryNational Center for Atmospheric Research3080 Center Green DriveBoulderCO 80301USA Jericho High School99 Cedar Swamp RoadJerichoNY 11753USA School of Space and EnvironmentBeihang UniversityBeijing 100091China 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2023年第23卷第12期

页      面：175-183页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：supported by the National Natural Science Foundation of China(NSFC,grant No.11973056) the National Key R&D Program of China(grant No.2021YFA1600500)。 

主　　题：The Sun-Sun magnetic fields-Sun photosphere-(Sun:)sunspots 

摘      要：Accurate measurement of magnetic fields is very important for understanding the formation and evolution of solar magnetic fields.Currently,there are two types of solar magnetic field measurement instruments:filter-based magnetographs and Stokes polarimeters.The former gives high temporal resolution magnetograms and the latter provides more accurate measurements of magnetic fields.Calibrating the magnetograms obtained by filter-based magnetographs with those obtained by Stokes polarimeters is a good way to combine the advantages of the two types.Our previous studies have shown that,compared to the magnetograms obtained by the Spectro-Polarimeter(SP)on board Hinode,those magnetograms obtained by both the filter-based Solar Magnetic Field Telescope(SMFT)of the Huairou Solar Observing Station and by the filter-based Michelson Doppler Imager(MDI)aboard SOHO have underestimated the flux densities in their magnetograms and systematic center-to-limb variations present in the magnetograms of both instruments.Here,using a sample of 75 vector magnetograms of stable alpha sunspots,we compare the vector magnetograms obtained by the Helioseismic and Magnetic Imager(HMI)aboard Solar Dynamics Observatory(SDO)with co-temporal vector magnetograms acquired by SP/Hinode.Our analysis shows that both the longitudinal and transverse flux densities in the HMI/SDO magnetograms are very close to those in the SP/Hinode magnetograms and the systematic center-to-limb variations in the HMI/SDO magnetograms are very minor.Our study suggests that using a filter-based magnetograph to construct a low spectral resolution Stokes profile,as done by HMI/SDO,can largely remove the disadvantages of the filter-type measurements and yet still possess the advantage of high temporal resolution.