Optimization of Photospheric Electric Field Estimates for Accurate Retrieval of Total Magnetic Energy Injection

Abstract

Estimates of the photospheric magnetic, electric and plasma velocity fields are essential for studying the dynamics of the solar atmosphere, for example through the derivative quantities of Poynting and relative helicity flux and by using of the fields to obtain the lower boundary condition for datadriven coronal simulations. In this paper we study the performance of a data processing and electric field inversion approach that requires only high-resolution and high-cadence line-of-sight or vector magnetograms-which we obtain from Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO). The approach does not require any photospheric velocity estimates, and the lacking velocity information is compensated using ad hoc assumptions. We show that the free parameters of these assumptions can be optimized to reproduce the time evolution of the total magnetic energy injection through the photosphere in NOAA AR 11158, when compared to the recent state-of-the-art estimates for this active region. However, we find that the relative magnetic helicity injection is reproduced poorly reaching at best a modest underestimation. We discuss also the effect of some of the data processing details on the results, including the masking of the noise-dominated pixels and the tracking method of the active region, both of which have not received much attention in the literature so far. In most cases the effect of these details is small, but when the optimization of the free parameters of the ad hoc assumptions is considered a consistent use of the noise mask is required. The results found in this paper imply that the data processing and electric field inversion approach that uses only the photospheric magnetic field information offers a flexible and straightforward way to obtain photospheric magnetic and electric field estimates suitable for practical applications such as coronal modeling studies.

Time-dependent data-driven coronal simulations of AR 12673 from emergence to eruption

“…The intensely flaring AR 12673 was observed using the Helioseismic and Magnetic Imager (HMI; Scherrer et al 2012) on board the Solar Dynamics Observatory (SDO; Pesnell et al 2012). We downloaded the full-disc disambiguated vector magnetic field observations (Hoeksema et al 2014), provided in their native 0.5 spatial resolution with a 720 s cadence, from the Joint Science Operations Center (JSOC) using ELECTRICIT (ELEC-TRIC field Inversion Toolkit; Lumme et al 2017). To support parts of the analysis, we used corresponding extreme ultraviolet (EUV) observations from the Atmospheric Imaging Assembly (AIA; Lemen et al 2012), also on board SDO.…”

“…Processing of the photospheric vector magnetogram data was performed according to the pipeline described in Lumme et al (2017) and Pomoell et al (2019) using the ELECTRICIT software toolkit. First, a time series of reprojected magnetogram cutouts that track the AR over its disc transit was created (example frames from this series are shown in Fig.…”

The PDFI_SS Electric Field Inversion Software

“…Yeates (2017) derived electric field solutions that combine solutions for the same inductive contribution as those above, but with the non-inductive contribution to the electric field determined from a "sparseness" constraint, to minimize unphysical artifacts of the horizontal electric field from the purely inductive solution. Lumme et al (2017); Price et al (2019) used solutions for all three components of the electric field using time derivatives for all three components of B, as described for the "PTD" solutions in KFW14, using a centered grid formalism. For the non-inductive contribution to E, they used the ad-hoc treatments suggested in Cheung & DeRosa (2012).…”

“…Here, in a change from the notation used in KFW14, we use P for the poloidal potential instead of B, and T for the toroidal potential instead of J . This change was made for notational simplicity, and also corresponds with the notation used by Lumme et al (2017). We also note another useful form for equation (4), namely…”

Forecasting the Structure and Orientation of Earthbound Coronal Mass Ejections

“…It is possible to use the method with only the line‐of‐the‐sight magnetic field (e.g., Yardley et al, ), but recent studies emphasize that the complete constraining of the driving electric field is required for capturing the complex dynamics of the coronal magnetic field consistent with EUV observations. This requires applying photospheric vector magnetograms as well as determining the velocity field by using Dopplergrams and optical flow methods, or alternatively by using carefully constrained ad hoc assumptions for the velocity‐dependent part of the electric field (e.g., Cheung et al, ; Fisher et al, ; Kazachenko et al, ; Lumme et al, ).…”