Скачать или смотреть On the Interaction between Solar Photospheric Flow and Magnetic Fields

IfA Dissertation Defense, 07/15/2025
Jiayi Liu, University of Hawaii, Institute for Astronomy
On the Interaction between Solar Photospheric Flow and Magnetic Field
Abstract:
The interaction between plasma flow and magnetic field transports energy and magnetic helicity through the solar photosphere. It plays a fundamental role in heating the corona and powering eruptions. An overarching goal of this dissertation is to accurately infer the flow fields from a time sequence of photospheric spectropolarimetric data, which is essential to quantifying the energy and helicity transport in both active regions and quiet Sun.
The first part focuses on studying the flow field in active regions. Specifically, I investigate the apparently supersonic Doppler flows in the core of active region 12673 with a new flow tracking method and SDO/HMI and Hinode/SP observations. I show that the flows are parallel to the magnetic fields, and the large Doppler velocity is just a projection effect. In the second part, in preparation for quiet-Sun studies with the 4-m Daniel K. Inouye Solar Telescope(DKIST), I explore the capability of its high-resolution observation in quantifying the energy transport with the realistic magnetohydrodynamic simulation and forward modeling. I find that existing method can capture the majority of unsigned energy flux, but the net flux remains poorly estimated. In the third part, using active region 12673 as an example, I investigate the reasons for significant discrepancies between several widely used methods that estimate energy and helicity flux. I demonstrate that the curl-free part of the electric field, which is not well-constrained by observation and is treated in ad hoc fashion, is the main cause for the differences.