README.txt written by E. Pariat on Dec 15th

This folder contains the z=0  & z= 150 L0 data necessary for the computation of the helicity flux of James Leake "unstable" simulation. "unstable" data comes from simulation case MD (Medium Dipole) in Leake, Linton and Antiochos (2014).

The ".sav" files correspond to  IDL save file format. 
They can be restored with e.g.:
IDL> restore,'unstable_2Dcut_unigrid_kcut273.sav'

The data are in non-dimensional units. A scaling is provided in Leake, Linton and Antiochos (2014) though it is not necessary for the project. the computation shall be done in non-dimensional units. 

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The "kcut71" files correspond to the bottom boundary (z=0) and the "kcut273" files to the top boundary (z=150 L0)

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The "unigrid" cases correspond to a uniformly spaced grid, exactly similar to the direct volume estimation data set.
The magnetic field and velocity fields have been interpolated on this grid. They can be directly compared with the direct helicity estimation. The grid is uniform

The "origrid" cases correspond to the original non uniform grid of the simulation.

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Each dataset, contains the following variables:

kcut=pixel index of the horizontal cut in James Leake original data set

zc= corresponding height of that cut, in units of L0 (the spatial scale)

time= 1D array of the corresponding instant of each data set. The time are given in units of t0 (the time scale)

xc & yc = 1D array corresponding to "x" and "y" values of the mesh points along the two axes in the horizontal directions. For the "unigrid" case they are uniformly spaced. For "origrid" they are non-uniform. 

bc = 4D array containing the vector components of the magnetic field for each cut at each time. The data are in units of B0 (the magnetic field scale). The two first dimension of the array correspond to the horizontal directions (hence to 'xc' and 'yc'). The third dimension of the array correspond to the different instant (hence to 'time'). The fourth dimension correspond to the three component of the field: 0='Bx' ; 1='By' & 2='Bz'.

vc = 4D array containing the vector components of the velocity field for each cut at each time. The data are in units of V0 (the velocity field scale). The two first dimension of the array correspond to the horizontal directions (hence to 'xc' and 'yc'). The third dimension of the array correspond to the different instant (hence to 'time'). The fourth dimension correspond to the three component of the field: 0='Vx' ; 1='Vy' & 2='Vz'.


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One obtains for example:

IDL> restore,'unstable_2Dcut_unigrid_kcut273.sav'
IDL> help
% At $MAIN$          
BC              DOUBLE    = Array[233, 233, 81, 3]
KCUT            INT       =      273
TIME            DOUBLE    = Array[81]
VC              DOUBLE    = Array[233, 233, 81, 3]
XC              DOUBLE    = Array[233]
YC              DOUBLE    = Array[233]
ZC              DOUBLE    =        148.98433


IDL> restore,'unstable_2Dcut_origrid_kcut71.sav'
IDL> help
% At $MAIN$          
BC              DOUBLE    = Array[279, 279, 81, 3]
KCUT            INT       =      71
TIME            DOUBLE    = Array[81]
VC              DOUBLE    = Array[279, 279, 81, 3]
XC              DOUBLE    = Array[279]
YC              DOUBLE    = Array[279]
ZC              DOUBLE    =        0.36184211