Improvements of the Longitudinal Magnetic Field Measurement from the Solar Magnetic Field Telescope at Huairou Solar Observing Station
arXiv:1904.07081 · doi:10.1007/s11207-021-01901-6
Abstract
The weak-field approximation implying linear relationship between Stokes and longitudinal magnetic field, , often suffers from saturation observed in strong magnetic field regions such as sunspot umbra. In this work, we intend to improve the magnetic field observations carried out by the \textit{Solar Magnetic Field Telescope} (SMFT) at Huairou Solar Observing Station, China. We propose using non-linear relationship between Stokes and to derive the magnetic field. To determine the form of the relationship, we perform a cross-calibration of the observed SMFT data and magnetograms provided by the \textit{Helioseismic and Magnetic Imager} on board the \textit{Solar Dynamics Observatory}. The algorithm of the magnetic field derivation is described in details. We show that using non-linear relationship between Stokes and allows us to eliminate magnetic field saturation inside sunspot umbra. The proposed technique enables one to enhance the reliability of the SMFT magnetic field data obtained even long before the space-based instrumentation era, since 1987.
16 pages, 9 figures, published by Solar Physics
References in corpus (7)
- The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs -- Space-weather HMI Active Region Patches
- The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
- VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager
- Inversion of the radiative transfer equation for polarized light
- New dynamo pattern revealed by solar helical magnetic fields
- A Non-Linear Magnetic Field Calibration Method for Filter-Based Magnetographs by Multilayer Perceptron
- From Polarimetry to Helicity: Studies of Solar Magnetic Fields at the Huairou Solar Observing Station