Tag Archives: helioseismology

183. Phase shifts measured in evanescent acoustic waves above the solar photosphere and their possible impacts on local helioseismology

Contributed by Junwei Zhao. Posted on July 31, 2022

Analysis on high-spectral resolution data shows that oscillations in the higher atmosphere lead those in the lower atmosphere by an order of 1 s when their frequencies are below about 3.0 mHz, and lags behind by about 1 s when their frequencies are above 3.0 mHz. These phase shifts in the evanescent waves pose great challenges to the interpretation of some local helioseismic measurements that involve data acquired at different atmospheric heights.

157. Forward Modeling Helioseismic Signatures of One- and Two-Cell Meridional Circulation

Contributed by Andrey M. Stejko. Posted on May 24, 2021

Helioseismic wavefields are simulated using different meridional-circulation models. Time-distance helioseismic measurements applied on the simulated data indicate that it may be difficult to distinguish between single- or double-cell meridional circulation profiles.

153. Computing Helioseismic Sensitivity Kernels for the Sun’s Large-scale Internal Flows Using Global-scale Wave-propagation Simulations

Contributed by Junwei Zhao. Posted on March 28, 2021

A new method to derive the helioseismic sensitivity kernels for the Sun’s large-scale internal flows is developed. The new method is based on the idea of placing a small-volume flow perturbation inside the Sun’s model, simulating the wavefield in the photosphere, and then measuring the phase shifts caused by this internal perturbation.