A new website is developed to host HMI’s time-distance pipeline products, including far-side images, subsurface flows, evolution of near-surface zonal and meridional flows.
A statistical study of hundreds of solar flares, with or without CMEs associated with them, indicates the larger the total magnetic flux of the flare-host active region, the less likely the flare is associated with a CME.
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.
A neural network has been developed and applied on helioseismic far-side images, and substantially improved the number of far-side active region detections with higher true positive rate.
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.
Similar to sunspots, the stable regions of pores on the Sun are also found to be defined by a critical value of the vertical component of the magnetic field. The critical value is comparable to that found in stable sunspots.
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.
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.
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.
Why do some flares cause sunquakes and others do not? A survey of 60 strong flares in Solar Cycle 24 supports a hypothesis that the coupling of downward photospheric oscillations and the impacts from flares may play a role in causing sunquakes.