DOI: 10.7910/dvn/kouaou
title: NLFFF extrapolations of AR10978 — boundary data

description: &lt;hr&gt;&lt;h2&gt;NLFFF extrapolations of AR10978 &mdash; boundary data&lt;/h2&gt;

&lt;h3&gt;Brief description&lt;/h3&gt;

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 &lt;a href=http://dx.doi.org/10.1088/0004-637X/811/2/107&gt;DeRosa et al. (2015)&lt;/a&gt;. This dataset contains the boundary
data used to constrain the NLFFF extrapolations. The data and metadata are
stored in the nonproprietary &lt;a href=https://www.hdfgroup.org/HDF5/&gt;HDF5
format&lt;/a&gt;, for which bindings exist in C, C++, Fortran90, IDL, Java, MATLAB,
Python, R, and many other languages. &lt;p&gt;

&lt;h3&gt;Filename convention&lt;/h3&gt;
The filenames below use the following convention:
&lt;ul&gt;
&lt;li&gt;&lt;code&gt;bin&lt;i&gt;XX&lt;/i&gt;_BC.h5&lt;/code&gt; : boundary data for bin level &lt;i&gt;XX&lt;/i&gt;
&lt;/ul&gt;&lt;p&gt;

&lt;h3&gt;Data and metadata contained in each file&lt;/h3&gt;

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. For each bin level, the data file
contains the following arrays:
&lt;ul&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;I_CONT&lt;/b&gt;&lt;/tt&gt;: continuum image&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;BXH&lt;/b&gt;&lt;/tt&gt;: &lt;i&gt;B&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; component, fill-fraction
 included, in G&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;BYH&lt;/b&gt;&lt;/tt&gt;: &lt;i&gt;B&lt;sub&gt;y&lt;/sub&gt;&lt;/i&gt; component, fill-fraction
 included, in G&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;BZH&lt;/b&gt;&lt;/tt&gt;: &lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt; component, fill-fraction
 included, in G&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;JZ&lt;/b&gt;&lt;/tt&gt;: normal component &lt;i&gt;J&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt; of the current
 density, in mA/m&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ALPHA&lt;/b&gt;&lt;/tt&gt;: force-free parameter &lt;i&gt;&alpha;&lt;/i&gt;, equivalent to
 &lt;i&gt;J&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt;/&lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt;, in Mm&lt;sup&gt;&minus;1&lt;/sup&gt;&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_BXH&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;B&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; component,
 propagated from the inversion output and not including disambiguation
 uncertainties&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_BYH&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;B&lt;sub&gt;y&lt;/sub&gt;&lt;/i&gt; component,
 propagated from the inversion output and not including disambiguation
 uncertainties&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_BZH&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt; component,
 propagated from the inversion output and not including disambiguation
 uncertainties&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_JZ&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;J&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt;, propagated
 from the inversion output and not including disambiguation
 uncertainties&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_ALPHA&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;&alpha;&lt;/i&gt;, propagated from
 the inversion output and not including disambiguation uncertainties&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_BXH_WD&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;B&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; component,
 as above but also including a penalization effect if &lt;tt&gt;AMBIG_CONF&lt;/tt&gt;
 is less than 0.9&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_BYH_WD&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;B&lt;sub&gt;y&lt;/sub&gt;&lt;/i&gt; component,
 as above but also including a penalization effect if &lt;tt&gt;AMBIG_CONF&lt;/tt&gt;
 is less than 0.9&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_BZH_WD&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;B&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt; component,
 as above but also including a penalization effect if &lt;tt&gt;AMBIG_CONF&lt;/tt&gt;
 is less than 0.9&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_JZ_WD&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;J&lt;sub&gt;z&lt;/sub&gt;&lt;/i&gt;, as above
 but also including a penalization effect if &lt;tt&gt;AMBIG_CONF&lt;/tt&gt; is less
 than 0.9&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ERR_ALPHA_WD&lt;/b&gt;&lt;/tt&gt;: uncertainty in &lt;i&gt;&alpha;&lt;/i&gt;, as above but
 also including a penalization effect if &lt;tt&gt;AMBIG_CONF&lt;/tt&gt; is less than
 0.9&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;AMBIG_CONF&lt;/b&gt;&lt;/tt&gt;: confidence level in ambiguity resolution
 (ranges from 0.5 to 1.0)&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ORIG_LATITUDE&lt;/b&gt;&lt;/tt&gt;: original latitude of each observed point&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;ORIG_CMD&lt;/b&gt;&lt;/tt&gt;: original longitude (central meridian distance)
 of each observed point&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;LOC_XY&lt;/b&gt;&lt;/tt&gt;: location, relative to disk center, in Mm of each
 point for &lt;i&gt;x&lt;/i&gt; and &lt;i&gt;y&lt;/i&gt;&lt;/li&gt;
&lt;li&gt;&lt;tt&gt;&lt;b&gt;OKDATA&lt;/b&gt;&lt;/tt&gt;: mask showing where edges that have no data reside
 (residual from interpolation to regularly spaced grid)&lt;/li&gt;
&lt;/ul&gt;&lt;p&gt;

Each file also contains a &lt;tt&gt;&lt;b&gt;POINT&lt;/b&gt;&lt;/tt&gt; substructure that contains
information about the remapping. The most useful quantities are probably
&lt;tt&gt;&lt;b&gt;XY_SIZE&lt;/b&gt;&lt;/tt&gt; (the pixel size of the remapped data in Mm) and
&lt;tt&gt;&lt;b&gt;RADIUS&lt;/b&gt;&lt;/tt&gt; (the radius of the sun in arcseconds as viewed from the
Hinode spacecraft).&lt;p&gt;

In the uncertainties having the &lt;tt&gt;&lt;b&gt;_WD&lt;/b&gt;&lt;/tt&gt; 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&deg;, 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 &lt;i&gt;B&lt;sub&gt;trans&lt;/sub&gt;&lt;/i&gt; vector in the middle
of it is undetermined (that is, it could just really go either way).&lt;p&gt;
&lt;hr&gt;