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Subsurface Flow Analysis Deployment

Science Testing Document

Input

  • The input for tracked Dopplergram datacube is the name of the 3D fits file, specified by the prefix -fi. Data of float type is accepted, there are no restrictions on size (subject to memory restrictions). The input FITS file remains unmodified.
  • Data resolution is specified in megameters per pixel using keyword -r.
  • The geometry configuration of the problem, i.e. the set of skip distances and corresponding phase speed filter parameters, are read from the file "GEOconfig.txt"

Optional Inputs

  • Travel time estimation method is specified by the switch -Gabor for Gabor wavelet fitting and -GB for travel time as perturbation to reference cross-correlation function (Gizon-Birch method). If no method is specified, Gizon-Birch method is used as default
  • To include low pass filter in pre-processing use -LP or -LowPass
  • To include difference filter in pre-processing use -DF
  • To include amplitude modulation correction use -AC
  • Annulus thickness is specified using -at in data pixels
  • Prefix for output files can be specified using -fo flag
  • The default averaging scheme is point to annulus with annulus thickness specified by keyword -at. To switch to point to quadrant averaging use -ns for North-South and -ew for East-West directions.
  • for more options please see documentation

Compilation and Execution:

code uses the following GNU Public License Libraries:

CFITSIO (for reading & writing FITS format files) http://heasarc.gsfc.nasa.gov/docs/software/fitsio/fitsio.html

FFTW (float version, i.e. libfftw3f.a library) http://www.fftw.org/, for Windows: http://www.fftw.org/install/windows.html

GSL (General Scientific Library) http://www.gnu.org/software/gsl/

  • gcc compilation: %gcc -o tt eSDOtt.c filters.c tt_estimate.c crosscorrelation.c -lgsl -lgslcblas -lcfitsio /usr/local/lib/libfftw3f.a -I$(LIBS)/cfitsio/include
  • commandline execution:
    * %./tt -fi fielname.fits -r 1.51815 -Gabor -at 3. -fo prefix -ns
    * %./tt -fi fielname.fits -r 1.51815 -Gabor -at 3. -fo prefix -DF -LP -AC -ew
    * %./tt -fi fielname.fits -r 1.51815 -at 3. -fo prefix -DF -LP -AC -xc xcor

AstroGrid workflow:

  • AstroGrid workflow instructions:
    • Open AstroGrid workbench and click "Task Launcher"
    • Task Launcher search: perturbation map generation or "Local Helioseismology Perturbation Map Generation"
    • Input:
    • Output:
      • OutputFile: tt_IO_NOAA8038_diff.fits (time travel differences: file reference; MySpace fits file)

Expected Output

  • final output:
    • output for travel_times is a fits file containing travel time differences for the set of skip-distance specified in GEOconfig.txt and selected averaging scheme
    • cross-correlation datacubes can be written into fits files when keyword -xcor or -xc is specified with string prefix
    • if keyword -testoutput is specified, FITS files containing filtered power spectrums will be also written
    • if keyword -geoascii is specified, ascii files containing details of the averaging annuli will be written for each skip-distance

  • current level of completion:
    • the fits files are written without any keywords
    • no directional filters for East-West and North-South averaging schemes currently implemented

  • limitations of algorithm:

Unit Testing

Classes with unit tests:

  • tt_estimate.c (contains currently 12 tests)
  • filters.c (contains currently 9 tests)
  • crosscorrelation.c (contains currently 5 tests)
compile:
gcc -Wall ttest.c allTests.c filters.c crosscorrelation.c tt_estimate.c -lgsl -lgslcblas -lcfitsio /usr/local/lib/libfftw3f.a -I$(LIBS)/cfitsio/include -o runtest

Science Test Cases

Case 1: Subsurface flows underneath isolated sunspot

Description

Estimate subsurface flows directly underneath a sunspot. The case has been extensively investigated using ray-approximation kernels (see Kosovichev et al, Kosovichev & Zhao).

Input

tracked and derotated Dopplergram (8hr or more) of the region under investigation lat22.5Nlon142.5_start.fits;
Born approximation sensitivity kernels and corresponding configuration file
center to annulus averaging scheme should be specified at run-time and Gizon Birch travel time extraction method should be selected as a means of travel time extraction
commandline execution
./tt -fi lat22.5Nlon142.5_start.fits -fo tt_IO_NOAA8038 -r 1.518 -s 1 -at 3 -LP
./tt -fi lat22.5Nlon142.5_start.fits -fo tt_NS_NOAA8038 -r 1.518 -s 1 -at 3 -LP -ns
./tt -fi lat22.5Nlon142.5_start.fits -fo tt_EW_NOAA8038 -r 1.518 -s 1 -at 3 -LP -ew
Each run will produce two files with mean and difference travel time perturbation, corresponding to waves travelling in and out each point, waves travelling in North-South nd waves travelling in East-West directions. For subsurface flow inversion we are interested in the travel-time divergences, which are then input into Local Helioseismology inversion. (see case 2 in Local Helio Inversion). Born approximation flow sensitivity kernel should be specified at the command line. Sound speed reciprocal is used as a regularisation. The result will be 3 3D datacubes providing components of subsurface flow vector field.
commandline execution:
./inv -fi tt_IO_NOAA8038_mean.fits -fo inv_IO_NOAA8038.fits -ri 1.518 -kr 1.518 -krn kernels/krnFlow_VZ.fits -abk -flow -eps 50. -pp 20.
./inv -fi tt_EW_NOAA8038_mean.fits -fo inv_EW_NOAA8038.fits -ri 1.518 -kr 1.518 -krn kernels/krnFlow_EW.fits -abk -flow -eps 50. -pp 20.
./inv -fi tt_NS_NOAA8038_mean.fits -fo inv_NS_NOAA8038.fits -ri 1.518 -kr 1.518 -krn kernels/krnFlow_NS.fits -abk -flow -eps 50. -pp 20.

Output

Travel-time differences for selected configurations (3D fits file) : East West, North South, In Out
Inversion of the travel-times (3D fits file) providing subsurface flow vector components (horizontal, East West and North South, and vertical directions) as function of position and depth.

Case 2: Active Region appearance

Description

Investigate the subsurface flows associated with the emergence of an Active Region.

Input

tracked and derotated Dopplergram (8hr or more) of the region under investigation;

Born approximation sensitivity kernels for flows and corresponding configuration file center to quadrants averaging scheme should be specified at run-time Gizon-Birch travel time extraction method should be chosen at run-time Low Pass filter and Amplitude Modulation correction should applied

./tt -fi lat22.5Nlon142.5_start.fits -fo tt_IO_NOAA10790 -r 1.518 -s 1 -at 3 -LP
./tt -fi lat22.5Nlon142.5_start.fits -fo tt_NS_NOAA10790 -r 1.518 -s 1 -at 3 -LP -ns
./tt -fi lat22.5Nlon142.5_start.fits -fo tt_EW_NOAA10790 -r 1.518 -s 1 -at 3 -LP -ew

As in case 1, two files will be output after each run, we are interested in travel time differences, which are inverted using Born approximation kernels for corresponding wave propagation direction (see case 2 in Local Helio Inversion).
commandline execution:
./inv -fi tt_IO_NOAA10790_mean.fits -fo inv_IO_NOAA10790.fits -ri 1.518 -kr 1.518 -krn kernels/krnFlow_VZ.fits -abk -flow -eps 50. -pp 20.
./inv -fi tt_EW_NOAA10790_mean.fits -fo inv_EW_NOAA10790.fits -ri 1.518 -kr 1.518 -krn kernels/krnFlow_EW.fits -abk -flow -eps 50. -pp 20.
./inv -fi tt_NS_NOAA8038_mean.fits -fo inv_NS_NOAA10790.fits -ri 1.518 -kr 1.518 -krn kernels/krnFlow_NS.fits -abk -flow -eps 50. -pp 20.

Expected Output

Travel-time differences for selected configurations (3D fits file) : East West, North South, In Out
Inversion of the travel-times (3D fits file) providing subsurface flow vector components (horizontal, East West and North South, and vertical directions) as function of position and depth.

NOTE: All .fits files have been moved from the attachments table to http://msslxx.mssl.ucl.ac.uk:8080/eSDO/algorithms/SubsurfaceFlow/SubsurfaceFlow.html .

-- ElizabethAuden - 04 Aug 2006

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Topic revision: r19 - 2008-01-14 - ElizabethAuden
 
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