Vol 14, No 11 (2014) / Teng

Some tests and improvements to the VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager

Fei Teng, Yuan-Yong Deng

Abstract

 

Some experimental tests and improvements to the Very Fast Inversion of the Stokes Vector program, which is designed for the inversion calculation used by the Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory, are given. On one hand, the interpolation for calculating the Voigt function is not smooth, which may occasionally cause the iteration process to converge to different minima although they are very close to initial values. This problem can be solved by a smoother interpolation. On the other hand, in order to improve the performance of this program, we have tried to abandon the randomly-jump-out strategy and set the initial value properly to avoid non-global minima. The resulting method costs only 1/4 of the computational time, and will be very competitive when the users are only interested in the vectorial magnetic fields and the velocities along the line of sight.


Keywords


Sun: magnetic fields — methods: numerical — techniques: polarimetric

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DOI: https://doi.org/10.1088/1674-4527/14/11/010

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