Photospheric magnetic and electric field maps for NOAA AR 11158

This dataset contains the main time series of photospheric magnetic and electric field maps in NOAA AR 11158 created for the publication Lumme et al. (2017).

The time series of photospheric magnetic field maps (i.e. vector magnetograms), ELECTRICIT_vector_magnetogram_series_AR11158.zip, was created from SDO/HMI disambiguated full-disk vector magnetograms using the ELECTRICIT software toolkit. The dataset contains the three components of the photospheric magnetic field (Bx,By,Bz) in local Cartesian coordinate system. The system is formed so that the photosphere is projected to a flat surface using Mercator projection centered at the location of the active region at each time (for further details see Lumme et al., 2017). Magnetograms are determined in a 744 x 610 grid with constant grid spacing of 0.03 deg (ca. 364 km) in the Mercator-projected heliographic coordinates. The time series spans from 2011 Feb 10 00:00 TAI to 2011 Feb 20 00:00 TAI (TAI is 37 seconds ahead of UT) with cadence of 12 minutes. The filename format is "{TIME}_{field_component}.fits".

Four time series of horizontal electric field maps (i.e. electrograms) and one time series of maps of the horizontal components of the magnetic vector potential were created. The following three series were created using the ELECTRICIT toolkit: ELECTRICIT_electrograms_AR11158_div_E0_and_vector_potential.zip, ELECTRICIT_electrograms_AR11158_div_E_omega_23_256.zip, ELECTRICIT_electrograms_AR11158_div_E_U_42.zip, where the titles refer to the use of the respective assumption for the non-inductive component - and thus also on the divergence - of the electric field (see the publication for details). The electric field components (Ex, Ey) are given in the same local Cartesian coordinate system as the magnetic field components described above. The first time series contains also the horizontal components of the vector potential (Ax, Ay) consistent with the Bz component of each magnetogram. Both the electric field and the vector potential are given in a staggered grid (Yee mesh, Yee, 1966) with respect to the magnetogram grid. Moreover, the electric field inversion is done in a way that crops one pixel from each side of the input magnetogram grid. Thus Ex (and Ax) component is given in 742 x 609 grid and Ey (and Ay) component in 743 x 608 grid. The time series spans from 2011 Feb 10 13:12 TAI to 2011 Feb 18 00:48 TAI.

The fourth electric field time series, DAVE4VM_electrograms_AR11158.zip, was created using DAVE4VM velocity inversion code from which output the electric field was calculated using the ideal Ohm's law. All three components of the electric field (Ex,Ey,Ez) are given in the same coordinate system and grid as the magnetic field series above. The time series spans from 2011 Feb 10 00:12 TAI to 2011 Feb 18 00:48 TAI.

June 28, 2011
Erkka Lumme
Space Physics Research Team
University of Helsinki

References:

Lumme, E., Pomoell, J., and Kilpua. E. K. J., Optimization of photospheric electric field estimates for accurate retrieval of total magnetic energy injection. Solar Physics. 2017, submitted.

Yee, K. Numerical solution of initial boundary value problems involving Maxwell's equations in isotropic media. IEEE Transactions on antennas and propagation. 1966.