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

TL;DR

VFISV is a highly optimized, fast inversion code for the Stokes vector, enabling routine, full-disk magnetic field mapping of the solar photosphere every 10 minutes using minimal computational resources.

Contribution

The paper introduces VFISV, a new inversion code that significantly speeds up the analysis of solar magnetic field data for large-scale, real-time applications.

Findings

VFISV can invert 16 million pixels every 10 minutes.

The code achieves high speed with minimal CPU resources.

Tests with Hinode data validate its accuracy and efficiency.

Abstract

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$\times$4096 pixels) of the magnetic field vector on the Solar Photosphere every 10 minutes. For this reason VFISV is optimized to achieve an inversion speed that will allow it to invert 16 million pixels every 10 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.