Tag Archives: subsurface flows

166. One-Sided Arc Averaging Geometries in Time-Distance Local Helioseismology

Contributed by David Korda. Posted on October 25, 2021

Instead of the center-annulus measurement geometry that time-distance helioseismology typically uses, a new one-sided center-arc measurement scheme is developed. This method shows advantage in measuring subsurface flows in in a close neighborhood of magnetic regions.

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.

155. Hydrodynamic Properties of the Sun’s Giant Polar Vortices

Contributed by David H. Hathaway. Posted on April 6, 2021

The giant cellular flows, obtained through tracking HMI-observed Dopplergrams, are used to estimate kinetic helicity and Reynolds stress inside the Sun, as well as differential rotation and poleward drift near the bottom of the convection zone.

134. The First Numerical Modeling of Spontaneous Generation of δ-sunspots

Contributed by Shin Toriumi. Posted on December 17, 2019

In an MHD simulation of flux emergence, a δ-sunspot is formed spontaneously by a collision of areas with opposite polarities. Driven by convective flows and counter-streaming flows, sheared polarity inversion lines form and flux ropes are created above.

133. Hemispherical Asymmetry in the Solar Meridional Flow

Contributed by B. Lekshmi. Posted on October 28, 2019

Subsurface meridional flows from ring-diagram analysis showed a clear hemispheric asymmetry in last 18 years. Interestingly, this flow asymmetry leads the magnetic flux and sunspot number asymmetry by 3.1 – 3.6 years.

122. Simultaneous Inversions for Vector Flows and Sound-Speed Perturbations

Contributed by Michal Švanda. Posted on March 6, 2019

To minimize cross-talk effect from vertical flows and sound-speed perturbations, a new inversion code is developed to invert for flows and sound-speed perturbations simultaneously from time-distance travel-time measurements. The code is validated using numerical simulation data.