143. The New HMI 96-Minute Vector Magnetograms
New HMI 96-minute vector magnetograms are now available. Deep averaging reduces noise and enhances long-lived magnetic structures.
142. On the Lorentz Force and Torque of Solar Photospheric Emerging Magnetic Fields
A large sample statistical study of normalized Lorentz force and torques in emerging magnetic field shows that the photospheric magnetic field has a rather small Lorentz forces and torques, close to a force-free state.
141. Source Depth of Three-minute Umbral Oscillations
Apparent 3-min waves observed inside sunspot umbrae are modeled as excited about 1000 to 2000 km beneath sunspots’ surface.
140. Solar Flare Predictive Features Derived from Polarity Inversion Line Masks in Active Regions Using an Unsupervised Machine Learning Algorithm
An unsupervised machine-learning algorithm is used on selected features derived from the polarity inversion lines (PIL) mask and difference PIL mask. It is found these features are effective in predicting flaring occurrences.
139. Using Synoptic Magnetograms for Long-Term Solar Activity Forecast
The Sun’s poloidal and toroidal magnetic field components derived from synoptic magnetograms are assimilated into a mean-field dynamo model, and activity level for Cycle 25 is predicted based on this approach.
138. Electric Current Neutralization in Solar Active Regions and Its Relation to Eruptive Activity
Electric current neutralization, which measures the ratio of direct current and return current inside active regions (ARs), is studied for a total of 30 AR samples. It is found that flare-productive ARs are more likely to exhibit non-neutralized currents than those flare-quiet ARs.
137. Imaging the Sunʼs Far-side Active Regions by Applying Multiple Measurement Schemes on Multiskip Acoustic Waves
Newly developed time-distance helioseismic imaging method, which includes more multiskip acoustic waves, is proved to be more reliable in mapping the Sun’s far-side active regions.
136. The Trigger Mechanism of Recurrent Solar Active Region Jets Revealed by the Magnetic Properties of a Coronal Geyser Site
This study explores the magnetic triggers of recurrent active region jets. Both widely debated triggers, namely, flux cancellation and flux emergence, are associated alternatively to the apparently homologous jets.
135. Serial Flaring in an Active Region: Exploring Why Only One Flare is Eruptive
Of three consecutive flares that occurred in a same active region within 4 hours, why were two non-eruptive and one eruptive? Non-linear force-free modeling suggest that breakout reconnection during the first two flares weakened the overlying field, allowing the flux rope to erupt in the third.
134. The First Numerical Modeling of Spontaneous Generation of δ-sunspots
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.