Contributed by Alexander Getling. Posted on October 31, 2022
Spectral analysis of the spatial structure of solar subphotospheric convection is carried out for subsurface flow maps. It is found that the horizontal flow scales increase rapidly with depth, from supergranulation to giant-cell values. The total power of the convective flows is found to be anticorrelated with the sunspot number variation over the solar activity cycle in shallow subsurface layers and positively correlated at larger depths.
Contributed by Andrey Stejko. Posted on October 28, 2022
Forward modeling is applied to numerous global hydrodynamic solar models, and helioseismic measurements on the meridional circulation are made using the forward modeling results. Comparison against the observational measurements shows significant differences, indicating our insufficient knowledge on either the global hydrodynamic modeling or the helioseismic inversions.
Contributed by Andreas Korpi-Lagg. Posted on October 17, 2022
Twelve years of HMI Dopplergram and magnetogram data have been used to uncover the solar cycle dependence of the magnetically quietest regions on the Sun and to reveal an enigmatic behavior of the surface-gravity wave energy contained in those regions.
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.
Contributed by Chris Hanson. Posted on June 27, 2022
High-frequency inertial waves were detected inside the Sun, propagating retrograde relative to the solar rotation with a phase speed faster than equatorial Rossby waves. How these waves are generated is discussed but remains unclear.
Contributed by Sean Quinn. Posted on November 23, 2021
Sunquakes are helioseismic waves excited by solar flares, usually observed in the photosphere. However, some of these events are found to have their counterparts in the chromosphere, as observed in the SDO/AIA UV channels.
Contributed by Fadil Inceoglu. Posted on November 3, 2021
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.
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.
Contributed by Samarth G. Kashyap. Posted on September 29, 2021
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.
Contributed by Junwei Zhao. Posted on September 10, 2021
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.