Tag Archives: active regions

195. Cross-Referenced NOAA Active Region List for Multi-Rotation Active Regions, 2011-2019 Now Available

Contributed by Emily Mason. Posted on September 22, 2023

It is well known that many active regions (ARs) last longer than one solar rotation, however, they are often assigned one NOAA AR number for each rotation. This work lists most, if not all, of the ARs that are a same AR but with different AR numbers.

194. Rossby waves and the organization of photospheric magnetic fields

Contributed by Breno Raphaldini. Posted on September 20, 2023

HMI magnetic field synoptic maps are used to evaluate the magnetic field structures’ organization and propagation as a function of time and latitude. It is demonstrated that the organization of longitudinal structures observed on synoptic maps is proportional to the level of activity at given latitudes.

192. Magnetic helicity and free magnetic energy as tools for probing eruptions in two differently evolving solar active regions

Contributed by Evangelia Liokati. Posted on July 29, 2023

An analysis of two active regions shows that differently evolving ARs may produce major eruptive flares even when, in addition to the accumulation of significant free magnetic energy budgets, they accumulate large amounts of both left- and right-handed helicity without a strong dominance of one handedness over the other.

187. Precursor Identification for Strong Flares Based on Anomaly Detection Algorithm

Contributed by Jingjing Wang. Posted on October 21, 2022

Some magnetic features in active regions, related to strong solar flares, are considered as “anomaly” features in a machine learning algorithm. An unsupervised auto-encoder network has been trained to identify such anomalies and is used to predict occurrence of strong flares.

174. Toward Improved Understanding of Magnetic Fields Participating in Solar Flares: Statistical Analysis of Magnetic Fields within Flare Ribbons

Contributed by Maria Kazachenko. Posted on February 24, 2022

Through analyzing a number of active regions, this analysis finds that while flares are guided by the physical properties that scale with AR size, CMEs are guided by mean properties, with little dependence on the amount of shear at the polarity inversion line or the net current.

173. Buildup of the Magnetic Flux Ropes in Homologous Solar Eruptions

Contributed by Rui Wang. Posted on February 17, 2022

This analysis shows that a new bipolar emergence, whose positive polarity collided with the pre-existing negative polarity, in AR11283 led to energy and helicity buildup in the form of magnetic flux ropes. Recurrent energy releases caused a few homologous CMEs from this region.

171. Flare-induced Sunquake Signatures in the Ultraviolet as Observed by the Atmospheric Imaging Assembly

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.

168. Introducing the SPEAR Catalogue from HMI Data

Contributed by Aimee Norton. Posted on October 29, 2021

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.