Author : Thierry Roudier (IRAP)
Contacts: Thierry Roudier (thierry.roudier/at/irap.omp.eu) & Martine Chane-Yook (martine.chane-yook/at/ias.u-psud.fr)
- Purpose:
We propose a set of codes written in IDL and Fortran, computing the horizontal velocity field on the Sun surface by using solar granules as tracers. CST codes take as input HMI/SDO intensity images with a time step of 45s. We use also the HMI/SDO Dopplergrams.
CST is provided under the GNU General Public License (GPL) version 3 or any later version.
doi : 10.48326/idoc.medoc.cst
- More informations:
Roudier (2012, A&A, 540, A88), Svanda (2013, the Astrophysical Journal, 771:32), Roudier (2013, A&A, 552, A113), Rincon (2017, A&A, 599, A69),
More references about small velocity fields:
Roudier (1999, Astron. Astrophys., 349, 301-311), Rieutord (2001, A&A, 377, L14-L17), Rieutord (2007, A&A, 471, 687-694), Tkaczuk (2007, A&A, 471, 695-703)
- Fortran, IDL files and documentations:
CST codes were successfully tested on clusters running linux with ifort compiler and SSWIDL. They are provided under the GNU General Public License (GPL) version 3 or any later version. doi : 10.48326/idoc.medoc.cst
Note (November 2021) concerning versions 1.0 and 1.1 : in IDL program files, 4096 has been replaced by 4095 in the formulas Xc and Yc. That correction takes into account the 0 origin of the first point of a matrix in IDL and induces a very minor impact on the results.
– Version 1.0 (November 2019) : the source codes are available here (CST_V1.0). For running the code, see the QUICKSTART guide. For more details on the codes, see the documentation.
– Version 1.1 (April 2020) : what is new compared to previous release is that IDL codes from step 3 are combined into one single IDL file. Furthermore, input file (param_seq_) and step 1 to 3 describing CST codes are explained in details in the documentation (see section 6 and 3). An automatic way to take HMI data from JSOC is proposed (see section 4 of the documentation) by T. Corbard (OCA). Click on the following links to download the package source file, the QUICKSTART guide and the documentation. Furthermore, formulas implemented in CST codes are described in details in section 7 of annex version 1.2 documentation (see below).
– Annex version 1.2 (March 2021) : solar granules deconvolution and horizontal velocity at higher spatial and temporal resolutions (0.5 Mm – 30 min; 1.3 Mm – 15 min). That CST application uses as input HMI/SDO intensity images (4096×4096 pixels) with a time step of 45s which are deconvolved by an IDL code (output intensity file in 8192×8192 pixels) before running the “deconvolved” Fortran part (see section 10 of the documentation). Click on the following links to download the package source file, the 15 min HMI intensities (29 nov 2018 data), the 30 min HMI observations (29 nov 2018 data), the QUICKSTART guide and the documentation.
– Improved documentation (May 2023) : proof of solar derotation formulas used in CST codes (see section 7.1.4 of the new version of documentation)
– Improved documentation (July 2023) : use of CST codes on deconvoluted data (see sections 5 and 6 of the new version documentation)
– Additional program to compute in spherical the divergence from Vphi and Vtheta, in 1/sec (April 2024) : The details of the mathematical calculations are given here.
- Output files (test case):
– image of the full Sun (October 21, 2010) : Solar segmented granules that are followed in time to get the horizontal velocities on all the Sun surface.
– image of the disc center (October 21, 2010) : Solar segmented granules visible at the disc center of Sun at high resolution
– image of the limb (October 21, 2010) : Solar segmented granules visible at the limb of Sun at high resolution. A Sunspot location is visible in the top left part of the image.
A workshop is dedicated to the training and use of the Coherent Structure Tracking (CST) software. It will take place on March 3-4, 2020 at IAS in Orsay, France. This workshop is open to all researchers and students of the international solar community, and is free but registration is mandatory before February, 29, 2020.
– Workshop website: https://cst2020-medoc.sciencesconf.org/
– Presentation by Thierry Roudier
– Limbshift, Beckers & Nelson, Solar Physics, Vol 58, Issue 2, pp. 243-261, 1978
– References on different methods of measuring surface movements
– Presentation by Martine Chane-Yook
