Forward Running Instructions


You may run the FORWARD codes from command line i.e.
Or you can now use the widget interface:
There are generally three widgets:
TOP (upper left),
MODEL (lower left), and
OPTIONS (upper right).

Help is available via a tab on each widget:

Models are called as argument of "for_drive" command, e.g.,
via the second button in the TOP widget. Model parameters are keywords and are changed via the MODEL widget.

  • Numerical datacube interface:
  • Potential field interface:
  • PSI MAS interface:
  • Analytic models:
    • "giblow" —(currently default) 3D MHD Gibson and Low (1998) model.
    • "cavmorph" —3D streamer plus cavity in spherically symmetric background. No magnetic field.
    • "liteslow" —Lites and Low 1996 model of spheromak magnetic field. "Unstretched" version of "giblow". Force balance not completely self-consistent between spheromak and external field.
    • "lowhund" —Low and Hundhausen 1995 Cartesian flux rope: partial implementation- see $FORWARD/MODELS/LOWHUND/LOWHUND_README.TXT for details.
    • Others can be added! Contact Sarah Gibson ( for assistance.
    • Papers describing the analytic models.

See $FORWARD/MODELS for a listing of models, and $FORWARD/DEFAULTS/ for explanation of general keywords. In each directory see MODELNAME_README.TXT and MODELNAMEHELP.TXT for details on particular models and their parameters.


Observables are called via keywords, e.g.,
via the third button in the TOP widget [Additional controls sometimes available in the OBS- tab of the OPTIONS widget and SPEC tab to its right.]

  • Multi-wavelength integrated (along LOS) observables:
    • SDO/AIA, SOHO/EIT, SOHO/CDS, TRACE, STEREO/EUVI (A and B), IRIS, PROBA/SWAP Hinode/XRT, Hinode/EIS, white light (pB and total Brightness)
        • **Note EUV/Xray Imagers and UV/EUV Spectrometers interface with Chianti spectral files**
    • CoMP-type Fe13, Fe14, Si9, Si10: Stokes I, Q, U, V, L (Q^2+U^2), V/I, Q/I, U/I, L/I
    • UV Spectropolarimetry (Permitted line unsaturated Hanle): BEING TESTED (OVI1032, OVI1037, LYA)
    • Radio thermal Bremsstrahlung, gyroreseonance, Faraday rotation
    • Diagnostics: LOS-integrated emission measure, column density (dual population model now available)

See $FORWARD/OBSERVABLES/ for a listing of observables, and $FORWARD/ for explanation of keywords.

Physical diagnostics are called via keywords, e.g.,
via the fourth button in the TOP widget.

  • Model physical diagnostics:
    • plasma: 'dens', 'temp', 'pres', 'ptot','vel'
    • B vector: 'br', 'bth, 'bph', 'bx', 'by', 'bz', 'bmag', 'bpos', 'beta'
    • positon: 'r', 'theta', 'phi' (useful for diagnostics)

Data FITS files can be put into FORWARD format from command line using routine for_plotfits, e.g.,
via the first button in the TOP widget (enabling easy model-data comparison when MOREPLOTS or NOERASE option is chosen in Output tab).

Data accesses either local files or uses VSO (or CoMP web page access) to download based on date.

    • In the widget, if MOREPLOTS or NOERASE is chosen in Output tab (second button, bottom row of TOP widget), the information of the data fits file will be preserved for future forward models. These include observable, line, viewing position (central meridian, solar Bangle) as well as field of view. MOREPLOTS will open new windows, NOERASE will overplot.

Fields of view are available in a range of types and sizes, controlled via keywords, e.g.,
via the FOV- tab in the OPTIONS widget.

  • Plane of sky map (default): r_pos,theta_pos —for a given central meridian.
  • Carrington map: latitude, longitude (for a given radial height).
  • User-defined points: RUSER=RUSER, THUSER=THUSER, PHUSER=PHUSER (these can be point, array, or matrix form).

See $FORWARD/ for explanation of keywords.

Line of sight integration and viewer position also can be adjusted through keywords, e.g.,
via the LOS- tab in the OPTIONS widget [Reducing to plane-of-sky integrated slice is allowed via the OBS- tab of the OPTIONS widget]

See $FORWARD/DEFAULTS/ for keywords pertaining to line-of-sight integration and viewer position.

Settings are controlled by keywords, e.g.,
via the fifth and sixth button in the TOP widget.

See $FORWARD/ for explanation of keywords.

Outputs are controlled by keyw.ord, e.g.,
via the second button, bottom row of the TOP widget.

  • Model results (the requested observable/parameter) can be extracted via output keyword quantmap=quantmap; for spectropolarimetry observables an additional output keyword stokesstruct=stokesstruct allows extraction of the full Stokes vector. If keyword savemap is set, quantmap (and stokesstruct) will be saved to a file (name set in keyword mapname).
  • The parameters used can be extracted via the keyword ModPramsStruct=ModPramsStruct; if keyword saveprams is set, they will be saved to a file (name set by saveprams).
  • All the model physical diagnostics can be extracted via ModSolStruct=ModSolStruct, which will provide values in the plane of sky even when the diagnostics are not explicitly requested.

See $FORWARD/ for explanation of keywords.

Plots are controlled by keywords, e.g.,
IDL>for_drive,/plotlog,title='my favorite plot'.
via the PLOT- tab and the DOCONT and (sometimes) the FIELDLINES and the STKLINES tabs to its right in the OPTIONS widget. Also sometimes the DONOISE tab to its left.

If DONOISE option available, noise will include photon and background, controlled by:
Telescope aperture,
Integration time,
Telescope efficiency,
Minimum noise (beyond which systematic errors dominate).

See $FORWARD/DEFAULTS/ for the explanation of keywords.

Noise can be plotted for CoMP-type data, see $FORWARD/DEFAULTS/ for details.