The results from a study to discern the dependence on spatial resolution by the various nonlinear force-free field (NLFFF) extrapolation methods are described in the Astrophysical Journal (http://dx.doi.org/10.1088/0004-637X/811/2/107). The citations for the boundary data used to constrain the NLFFF extrapolations, as well as the analysis volumes of the extrapolations themselves, are below. Clicking on the DOI links will lead to a webpage from which the data can be downloaded.
| Boundary data | DeRosa, M.L. et al., 2015, “NLFFF extrapolations of AR10978 — boundary data”, http://dx.doi.org/10.7910/DVN/KOUAOU, Harvard Dataverse, v1.2 |
| Analysis volumes | DeRosa, M.L. et al., 2015, “NLFFF extrapolations of AR10978 — analysis volumes”, http://dx.doi.org/10.7910/DVN/7ZGD9P, Harvard Dataverse, v1.2 |
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Introduction
The results from a study to discern the dependence on spatial resolution by the various nonlinear force-free field (NLFFF) extrapolation methods are described in the Astrophysical Journal. This webpage provides links to the boundary data used to constrain the NLFFF extrapolations, as well as to the analysis volumes of the extrapolations themselves.
Links to boundary data
The remapped vector magnetogram data that were used as lower boundary conditions to produce the NLFFF extrapolations are available for download via the links in the table below. As described in the ApJ article, the data have been interpolated onto a uniform grid, and projected to a helioplanar coordinate system so that the data appear as if AR10978 were at disk center. The data and metadata are stored in the nonproprietary HDF5 format, for which bindings exist in C, C++, Fortran90, IDL, Java, MATLAB, Python, R, etc. For each case, the data file contains the following arrays:
| I_CONT | continuum image |
| BXH | Bx component, fill-fraction included, in G |
| BYH | By component, fill-fraction included, in G |
| BZH | Bz component, fill-fraction included, in G |
| JZ | normal component Jz of the current density, in mA/m2 |
| ALPHA | force-free parameter α, equivalent to Jz/Bz, in Mm−1 |
| ERR_BXH | uncertainty in Bx component, propagated from the inversion output and not including disambiguation uncertainties |
| ERR_BYH | uncertainty in By component, propagated from the inversion output and not including disambiguation uncertainties |
| ERR_BZH | uncertainty in Bz component, propagated from the inversion output and not including disambiguation uncertainties |
| ERR_JZ | uncertainty in Jz, propagated from the inversion output and not including disambiguation uncertainties |
| ERR_ALPHA | uncertainty in α, propagated from the inversion output and not including disambiguation uncertainties |
| ERR_BXH_WD | uncertainty in Bx component, as above but also including a penalization effect if AMBIG_CONF is less than 0.9 |
| ERR_BYH_WD | uncertainty in By component, as above but also including a penalization effect if AMBIG_CONF is less than 0.9 |
| ERR_BZH_WD | uncertainty in Bz component, as above but also including a penalization effect if AMBIG_CONF is less than 0.9 |
| ERR_JZ_WD | uncertainty in Jz, as above but also including a penalization effect if AMBIG_CONF is less than 0.9 |
| ERR_ALPHA_WD | uncertainty in α, as above but also including a penalization effect if AMBIG_CONF is less than 0.9 |
| AMBIG_CONF | confidence level in ambiguity resolution (ranges from 0.5 to 1.0) |
| ORIG_LATITUDE | original latitude of each observed point |
| ORIG_CMD | original longitude (central meridian distance) of each observed point |
| LOC_XY | location, relative to disk center, in Mm of each point for x and y |
| OKDATA | mask showing where edges that have no data reside (residual from interpolation to regularly spaced grid) |
Each file also contains a POINT substructure that contains information about the remapping. The most useful quantities are probably XY_SIZE (the pixel size of the remapped data in Mm) and RADIUS (the radius of the sun in arcseconds as viewed from the Hinode spacecraft).In the uncertainties having the _WD suffix, note that disambiguation uncertainties were propagated as follows: where 100 trials (100 random number seeds) of the disambiguation did not agree 90% of the time, those azimuth errors were set to 180°, possibly resulting in apparently large spikes in uncertainties (as compared with more reasonable neighboring pixels). Most of these are in weak-signal areas, but not all. However, in strong-signal areas, these uncertainty spikes occur where, e.g., there’s a divergence-point and the single Btrans vector in the middle of it is undetermined (that is, it could just really go either way).
| Boundary Data File | File Size | |||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bin 2 | bin02_BC.h5
| 19 MB
| Bin 3
| bin03_BC.h5
| 8.6 MB
| Bin 4
| bin04_BC.h5
| 4.8 MB
| Bin 6
| bin06_BC.h5
| 2.1 MB
| Bin 8
| bin08_BC.h5
| 1.2 MB
| Bin 10
| bin10_BC.h5
| 780 KB
| Bin 12
| bin12_BC.h5
| 540 KB
| Bin 14
| bin14_BC.h5
| 400 KB
| Bin 16
| bin16_BC.h5
| 320 KB | |
Links to extrapolation analysis volumes
The analysis volumes from all 71 NLFFF extrapolations that were analyzed as part of the ApJ article are available for download via the links in the table below, organized by method/code (CFIT, FEMQ, magnetofrictional, optimization, and XTRAPOL) and bin level. For the Grad-Rubin methods, both the N and P solutions are provided. As above, the data are stored in the HDF5 format, and in each file are included the extrapolation cubes as well as arrays that index each of the three dimensions (in Mm).
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