NLFFF extrapolations of AR10978 — boundary data

NLFFF extrapolations of AR10978 — boundary data Brief description 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 DeRosa et al. (2015). This dataset contains the boundary data used to constrain the NLFFF extrapolations. The data and metadata are stored in the nonproprietary HDF5 format, for which bindings exist in C, C++, Fortran90, IDL, Java, MATLAB, Python, R, and many other languages. Filename convention The filenames below use the following convention: binXX_BC.h5 : boundary data for bin level XX Data and metadata contained in each file 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: 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).

AR10978的非线性无力场（Nonlinear Force-Free Field, NLFFF）外推——边界数据 简要说明
DeRosa等人（2015年）的研究阐述了各类非线性无力场外推方法对空间分辨率的依赖关系，本数据集即为用于约束该类NLFFF外推的边界数据。数据与元数据以非专有HDF5格式存储，该格式支持C、C++、Fortran90、IDL、Java、MATLAB、Python、R等诸多编程语言的绑定库。

文件名约定
下述文件名遵循如下命名规则：binXX_BC.h5：对应bin层级XX的边界数据。

数据与元数据内容
如《天体物理学杂志（Astrophysical Journal, ApJ）》论文所述，所有数据已被插值至均匀网格，并投影至日面平面坐标系，使得数据呈现为AR10978位于日面中心时的观测效果。针对每个bin层级，数据文件包含如下数组：
I_CONT：连续谱图像
BXH：Bx分量（包含填充因子，单位：高斯（G））
BYH：By分量（包含填充因子，单位：高斯（G））
BZH：Bz分量（包含填充因子，单位：高斯（G））
JZ：电流密度法向分量Jz，单位：毫安每平方米（mA/m²）
ALPHA：无力场参数α，等价于Jz/Bz，单位：每兆米（Mm⁻¹）
ERR_BXH：Bx分量的不确定度，由反演输出传递而来，不包含消歧义不确定度
ERR_BYH：By分量的不确定度，由反演输出传递而来，不包含消歧义不确定度
ERR_BZH：Bz分量的不确定度，由反演输出传递而来，不包含消歧义不确定度
ERR_JZ：Jz的不确定度，由反演输出传递而来，不包含消歧义不确定度
ERR_ALPHA：α的不确定度，由反演输出传递而来，不包含消歧义不确定度
ERR_BXH_WD：Bx分量的不确定度，与上述规则一致，但当AMBIG_CONF小于0.9时，会引入惩罚效应
ERR_BYH_WD：By分量的不确定度，与上述规则一致，但当AMBIG_CONF小于0.9时，会引入惩罚效应
ERR_BZH_WD：Bz分量的不确定度，与上述规则一致，但当AMBIG_CONF小于0.9时，会引入惩罚效应
ERR_JZ_WD：Jz的不确定度，与上述规则一致，但当AMBIG_CONF小于0.9时，会引入惩罚效应
ERR_ALPHA_WD：α的不确定度，与上述规则一致，但当AMBIG_CONF小于0.9时，会引入惩罚效应
AMBIG_CONF：消歧义置信度（取值范围为0.5至1.0）
ORIG_LATITUDE：每个观测点的原始纬度
ORIG_CMD：每个观测点的原始经度（中心子午线距离，Central Meridian Distance, CMD）
LOC_XY：每个点相对于日面中心的x、y方向位置，单位：兆米（Mm）
OKDATA：掩码数组，用于标记无数据的边缘区域（为插值至规则网格后的残差结果）

每个文件还包含一个POINT子结构，用于存储重映射相关信息。其中最实用的参数或许为XY_SIZE（重映射后数据的像素尺寸，单位：Mm）与RADIUS（从日出号（Hinode）航天器观测视角得到的太阳半径，单位：角秒）。

对于带有_WD后缀的不确定度，需注意消歧义不确定度的传递规则如下：当100次消歧义试验（使用100个随机数种子）的结果一致性未达到90%时，对应的方位角误差将被设为180°，这可能会导致不确定度出现明显的尖峰（相较于相邻像素的合理不确定度而言）。此类尖峰大多出现在弱信号区域，但并非全部。然而在强信号区域，当出现诸如发散点且其中间的单一横向磁场矢量无法确定（即其方向确实存在两种可能性）时，也会出现此类不确定度尖峰。