Helioseismic and Magnetic Imager Multi-height Dopplergrams

TL;DR

This paper analyzes multi-height Doppler velocity measurements in the solar atmosphere using HMI filtergrams, revealing significant phase differences indicative of multi-height data in the high-frequency range.

Contribution

It demonstrates the multi-height nature of Doppler measurements from HMI filtergrams through phase difference analysis in the high-frequency domain.

Findings

Significant phase differences observed between core and wing Dopplergrams.

Confirmation of multi-height data in the solar atmosphere.

Potential implications for solar atmospheric studies.

Abstract

We study Doppler velocity measurements at multiple heights in the solar atmosphere using a set of six filtergrams obtained by the Helioseismic magnetic Imager on board the Solar Dynamics Observatory. There are clear and significant phase differences between core and wing Dopplergrams in the frequency range above the photospheric acoustic cutoff frequency, which indicates that these are really "multi-height" datasets.