| Presentation Title: | The Behavior of the Magnetic Field in Sun's High-latitude Regions
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| Author(s): | Nariaki Nitta, Rebecca Centeno, Yang Liu, Jon Linker
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Abstract:
The line-of-sight magnetograms from SDO/HMI suggest the difficulty of determining if and when the polar magnetic field has reversed or will reverse during solar cycle 25, depending on the definition of the polar regions. We compare vector magnetic field measurements of the polar regions by Hinode/SOT and HMI over a period that encompasses solar cycles 24 and 25 and discuss the realistic uncertainties in the magnetic flux from the polar regions. In addition, using SDO/AIA data, the frequency of brightenings is studied in various latitudinal zones above 60 degrees up to the poles. A large subset of these brightenings, which may or may not accompany coronal jets, are thought to result from reconnection of magnetic field elements of prevailing polarity of either pole with those of the opposite polarity that are expected to increase as we approach the solar maximum. We discuss implications of this study in the so-called open magnetic flux problem and possible improvement of heliospheric numerical models.