MDR-NFFF

Non-Force-Free-Field extrapolation code based on the Minimum Dissipation Rate (MDR) principle. See Hu et al. 2010 for details on the implementation.

Table of Contents

• MDR-NFFF
  • Table of Contents
  • Dependencies
  • Input File Parameters Documentation
    • Input Paths
    • Event Details
    • Data Input Settings
      • Additional Settings for 'sav' Format
      • Additional Settings for 'fcube' Format
    • Cropping Details
    • Run Mode
    • NFFF Extrapolation Settings
    • Output Settings
    • Additional Comments
    • Example Input File
  • Issues and suggestions
  • Contact

---

Dependencies

The code is written in IDL (Interactive Data Language) and requires the some functions from the following dependencies:

• Calculate Squashing Factor and Twist Number: qfactor
• Updated versions of the Squashing Factor code are also available at: FastQSL (CPU) and FastQSL (GPU)
• SolarSoft IDL: SSW
• Collection of IDL routines written and maintained by Chris Beaumont beaumont-idl-library

Input File Parameters Documentation

This section provides detailed explanations and input examples of the parameters defined in the input_sample.pro file. The first step is to rename input_sample.pro to input.pro before running any codes.

The input.pro file serves as a common input file to pass parameters to various codes used for the non-force-free field extrapolation code bnfff.pro or any related procedures.

Input Paths

• codesdir: (String)

  Path to the root directory containing all the codes. This path will be added to the top of your IDL path. This is where this input.pro file should be present.

  codesdir = '/Users/avijeetp/codes/extrapolation/'

• projectdir: (String)

  Path to the main project folder or the hard-disk path where your project resides. This would be top folder under which the outputs will be saved.

  projectdir = '/Users/avijeetp/extrapolations/'

Event Details

• event: (String)

  Name of the event to analyze. Typically, this is the NOAA number of an active region (e.g., 'AR12192'). For quiet sun data, you can set any other string eg. event = 'QS'.

  event = 'AR12192'

• source: (String)

  Name of the instrument used as the data source. Examples: 'sdo_hmi', 'hinode_sot', 'sst_crisp'. This is used to identify the source of the data and load the appropriate routines.

  source = 'sdo_hmi'

• ds: (String)

  Dataseries name. Examples: 'hmi.B_720s', 'hmi.sharp_cea_720s', 'hmi.sharp_cea_720s_dconS', 'nb_6173', etc.

  ds = 'hmi.sharp_cea_720s'

• tobs: (String or Array of Strings)

  Time of the observation in the format 'HH:MM DD-MMM-YYYY'. It can be a single string or an array of strings with start and end time. Examples: '09:36 20-oct-2023', ['10:00 26-jul-2023', '10:24 26-jul-2023', '12'].

  tobs = '09:36 20-oct-2023'

Data Input Settings

• dataformat: (String)

  Format of the input data. Options are 'fits', 'sav', 'fcube'.

  • 'fits': For JSOC downloads or FITS files.
  • 'sav': For data already saved in an IDL .sav file.
  • 'fcube': For data in cube format (e.g., SST cubes).

  dataformat = 'fits'

Additional Settings for 'sav' Format

If dataformat is set to 'sav', the following parameters should be specified:

• savdir: (String)

  Directory path where the .sav file is located.

  savdir = projectdir

• savfile: (String)

  Name of the .sav file containing the data.

  savfile = '201109062236_bxbybz.sav'

• bvecs: (Array of Strings)

  Names of the magnetic field components within the .sav file. Typically ['bx', 'by', 'bz'].

  bvecs = ['bx', 'by', 'bz']

Additional Settings for 'fcube' Format

If dataformat is set to 'fcube', specify the following:

• datadir: (String)

  Directory path where the cube data is saved.

  ; datadir = '/Users/avijeetp/1_Projects/2020-08-07/'

Cropping Details

• check_crop: (String)

  Determines how to handle the cropping of the data. Options are:

  • 'yes': Opens an interactive window to define cropping details.
  • 'no': Uses predefined cropping parameters without user interaction.

  check_crop = 'yes'

If check_crop is set to 'no', the following parameters must be specified:

• xsize: (Integer)

  Number of pixels in the x-direction after cropping.

  xsize = 1280

• ysize: (Integer)

  Number of pixels in the y-direction after cropping.

  ysize = 832

• xorg: (Integer)

  X-coordinate of the bottom-left pixel in the cropped region.

  xorg = 50

• yorg: (Integer)

  Y-coordinate of the bottom-left pixel in the cropped region.

  yorg = 0

• scl: (Float)

  Scaling factor for rescaling the data. The data will be rescaled to xsize / scl.

  scl = 1.0

• nz: (Integer)

  Number of grid points in the z-direction. Typically calculated as ysize / scl.

  nz = 416

Run Mode

• mode: (String)

  Determines whether to perform a new calculation or analyze an existing run. Options are:

  • 'calculate': Initiates a new calculation and automatically generates a run ID based on the timestamp.
  • 'analysis': Analyzes results from a previous run using specified run IDs.

  mode = 'calculate'

If mode is set to 'analysis', specify the following:

• ids/id: (Array of Strings)

  • Single ID Example: id = '1673877191'

  • List of run IDs to analyze.

  ids = [ $
    '1710927883', $
    '1710937796' $
    ]

---

NFFF Extrapolation Settings

Parameters specific to the Non-Force-Free Field (NFFF) extrapolation:

• nk0: (Integer)

  Number of iterations in the potential field correction loop. A typical value is >= 300.

  nk0 = 3000

• nl: (Integer)

  Number of steps in the alpha loop. A typical value is >= 8.

  nl = 8

• itaperx: (Integer)

  Tapering parameter in the x-direction, based on the domain size.

  itaperx = 16

• itapery: (Integer)

  Tapering parameter in the y-direction, based on the domain size.

  itapery = 8

• dx: (Float)

  Grid spacing in the x-direction. Only uniform grids are supported.

  dx = 1

• dz: (Float)

  Grid spacing in the z-direction. Non-uniform grids in z are possible but not yet supported.

  dz = 1

• wt_set: (Float)

  Weighting factor with the transverse field strength for calculating the normalized energy (En).

  wt_set = 1.1

---

Output Settings

Settings related to the output of the extrapolation and analysis:

• current: (Integer)

  Flag to calculate the electric current. Set to 1 to enable calculation, 0 to disable.

  current = 1

• qfactor: (Integer)

  Flag to calculate the squashing factor (Q-factor). Requires ifort (Intel Fortran Compiler). Set to 1 to enable, 0 to disable.

  qfactor = 1

• qpath: (String)

  Path to the directory containing the qfactor calculation libraries.

  qpath = codesdir + 'MDR-NFFF/libs/qfactor/'

• decay: (Integer)

  Flag to calculate the decay index. Set to 1 to enable, 0 to disable.

  decay = 1

• vapor: (Integer)

  Flag to save output in VAPOR (Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers) format. Requires VAPOR software. Set to 1 to enable, 0 to disable.

  vapor = 1

• outtxt: (Integer)

  Flag to save data output in .dat format for reading in EULAG (Eulerian and Lagrangian fluid dynamics code). Set to 1 to enable, 0 to disable.

  outtxt = 0

---

Note: Ensure all paths specified exist on your system, and the required software dependencies (like ifort and VAPOR) are installed if you enable features that require them.

---

Additional Comments

• Always verify the parameter values before running any codes to avoid unexpected behavior.
• The parameters xsize, ysize, xorg, yorg, scl, and nz are critical for data cropping and must be set accurately if check_crop is set to 'no'.
• The mode parameter controls whether a new calculation is performed or existing results are analyzed. Ensure that run IDs are correctly specified when in 'analysis' mode.
• The NFFF extrapolation parameters (nk0, nl, itaperx, itapery, dx, dz, wt_set) should be set based on the specifics of your simulation and desired accuracy.

Example Input File

; --- Input paths ---
codesdir = '/Users/avijeetp/codes/idl/extrapolation/' ; Enter the path to root directory to all your codes
projectdir = '/Users/avijeetp/extrapolations/'; Enter the hard-disk path or the path to the main project folder
event = 'AR12192' ; Enter the event name. Typically the NOAA number of an active region
source = 'sdo_hmi' ; Enter the instrument name as the data source
ds = 'hmi.sharp_cea_720s' ; Enter the dataseries name
tobs = '09:36 20-oct-2023' ; Enter the time of the observation
dataformat = 'fits' ; Enter the input data format

; --- Cropping details ---
check_crop = 'no' ;
if (check_crop eq 'no') then begin
  xsize = 1280 ; number of pixels in x after cropping
  ysize = 832 ; number of pixels in y after cropping
  xorg = 50 ; x coordinate of bottom left pixel
  yorg = 0 ; y coordinate of bottom left pixel
  scl = 1. ; factor for rescaling the data to xsize / scl
  nz = 416 ; specify nz based on the scl value, typically nz = ysize / scl
endif
mode = 'calculate' ; run mode is calculate

; --- NFFF Extrapolation settings ---
nk0 = 3000 ; number of loops in potential field correction,typically >= 300
nl = 8 ; number of steps in the alpha loop, typically >= 8
itaperx = 16 ; tapering in x, based on domain size
itapery = 8 ; tapering in y, based on domain size
dx = 1 ; step size in x (only uniform grid supported)
dz = 1 ; step size in z (non-uniform grid in z possible but not yet supported)
wt_set = 1.1 ; weight with transverse field strength for calculating En

; --- output settings ---
current = 1 ; 0/1 calculate current
qfactor = 1 ; 0/1 calculate qfactor -> needs ifort
qpath = codesdir + 'MDR-NFFF/libs/qfactor/' ; path to qfactor executable
decay = 1 ; 0/1 calculate decay index
vapor = 1 ; 0/1 save output as vapor file -> needs vapor
outtxt = 0 ; 0/1 save dat output for reading in EULAG

---

Issues and suggestions

Issues and suggestions can be reported here.

Contact

For any questions or further assistance, please contact the author:

Author: Avijeet Prasad
Created On: 2024-11-14