Quasi-biennial oscillations are found in the Sun’s interior rotation-rate residuals. They appear differently at different depths and latitudes, and evolve with time.
In order to make the properties of magnetic features observed by SDO/HMI more accessible, the Solar Photospheric Ephemeral and Active Region (SPEAR) catalogue has been created as an easy-to-read tabulated text file. Tilt angles from the SPEAR catalogue are shown as a histogram (top) and as a function of latitude (bottom) with colors indicating all regions (blue), regions with anti-Joy (red), and anti-Hale (purple) tilts. Over 40% of regions disobey the laws of Joy and Hale.
An unprecedented observation of a limb flare in HMI’s white-light continuum shows that the white-light intensity at the post-flare loop-top continues to grow for 16 more minutes while UV/EUV intensities decay. Both the WL/UV intensity and the EUV intensities show quasi-periodic pulsations with a period close to 8.0 and 6.8 minutes, respectively.
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.
A time variable center-to-limb effect in photospheric velocity measurements through local correlation tracking is identified, and a robust methodology to correct for it is developed.
A new method, which is to characterize the multiscale convective spectrum of the Sun using high-resolution line-of-sight Dopplergram images from HMI, is developed, enabling the authors to estimate the spectrum to the finest observable scales.
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.