161. Changes in granulation scales over the solar cycle seen with SDO/HMI and Hinode/SOT

Contributed by J. Ballot. Posted on August 29, 2021

An analysis of granule sizes over a few years of HMI observations shows that, even in quite regions, the granular size shows an anti-correlation with the solar magnetic activity with a time delay of about 300 days. The granular size decreases by about 2% during the activity maximum relative to the minimum.

159. Magnetic Field Dependence of Bipolar Magnetic Region Tilts on the Sun: Indication of Tilt Quenching

Contributed by Bibhuti Kumar Jha. Posted on June 15, 2021

Magnetic-field dependence of active regions’ tilt angles are analyzed using the MDI and HMI observations for two solar cycles. The variation of the tilt angles with the maximum magnetic-field strength of the ARs indicates a nonlinear tilt quenching in the Babcock–Leighton process.

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.

156. Fast and Accurate Emulation of the SDO/HMI Stokes Inversion with Uncertainty Quantification

Contributed by Richard Higgins. Posted on April 16, 2021

An emulation of the VFISV Stokes Inversion that trains a deep
network (U-Net) to map directly from IQUV polarized light to Milne-Eddington magnetic field parameters. The accuracy of this method suggests that it could serve as a warm-start for VFISV or as a pre-disambiguation stand-in.

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.