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

作　　者：Mei Zhang Haocheng Zhang Chengqing Jiang 

机构地区：[1]National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China [2]School of Astronomy and Space Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]High Altitude Observatory,National Center for Atmospheric Research,3080 Center Green Drive,Boulder,CO 80301,USA [4]Jericho High School,99 Cedar Swamp Road,Jericho,NY 11753,USA [5]School of Space and Environment,Beihang University,Beijing 100091,China

出　　处：《Research in Astronomy and Astrophysics》2023年第12期175-183,共9页天文和天体物理学研究（英文版）

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)。

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.

关 键 词：The Sun-Sun magnetic fields-Sun photosphere-(Sun:)sunspots 

分 类 号：P182.22[天文地球—天文学]