VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager

• Published in: Solar physics 2011-10, Vol.273 (1), p.267-293
• Main Authors: Borrero, J. M., Tomczyk, S., Kubo, M., Socas-Navarro, H., Schou, J., Couvidat, S., Bogart, R.
• Format: Article
• Language: English
• Subjects: Astrophysics and Astroparticles; Atmospheric Sciences; Fluid flow; Inversions; Magnetic fields; Mathematical analysis; Physics; Physics and Astronomy; Pixels; Radiative transfer; Simplification; Solar flares; Solar physics; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Spacecraft; Vectors (mathematics)
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1007/s11207-010-9515-6

In this paper we describe in detail the implementation and main properties of a new inversion code for the polarized radiative transfer equation (VFISV: Very Fast Inversion of the Stokes Vector). VFISV will routinely analyze pipeline data from the Helioseismic and Magnetic Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It will provide full-disk maps (4096×4096 pixels) of the magnetic field vector on the Solar Photosphere every ten minutes. For this reason VFISV is optimized to achieve an inversion speed that will allow it to invert sixteen million pixels every ten minutes with a modest number (approx. 50) of CPUs. Here we focus on describing a number of important details, simplifications and tweaks that have allowed us to significantly speed up the inversion process. We also give details on tests performed with data from the spectropolarimeter on-board of the Hinode spacecraft.