Graham Steward

AUTOMATIC RECOGNITION OF CORONAL TYPE II RADIO BURSTS: THE AUTOMATED RADIO BURST IDENTIFICATION SYSTEM METHOD AND FIRST OBSERVATIONS

Major space weather events such as solar flares and coronal mass ejections are usually accompanied by solar radio bursts, which can potentially be used for real-time space weather forecasts. Type II radio bursts are produced near the local plasma frequency and its harmonic by fast electrons accelerated by a shock wave moving through the corona and solar wind with a typical speed of ~1000 km s?1. The coronal bursts have dynamic spectra with frequency gradually falling with time and durations of several minutes. This Letter presents a new method developed to detect type II coronal radio bursts automatically and describes its implementation in an extended Automated Radio Burst Identification System (ARBIS 2). Preliminary tests of the method with spectra obtained in 2002 show that the performance of the current implementation is quite high, ~80%, while the probability of false positives is reasonably low, with one false positive per 100-200?hr for high solar activity and less than one false event per 10000?hr for low solar activity periods. The first automatically detected coronal type II radio burst is also presented.

Severe Space Weather Events in the Australian Context

Abstract The Space Weather Services (SWS) section of the Australian federal government is responsible for providing space weather information to the Australasian and surrounding regions while also providing niche services in high-frequency radio to the rest of the world. SWS emerged in 2014 as a successor to the Ionospheric Prediction Service (IPS), which had been in operation since 1947. Australia is in somewhat of a unique geographic position as a large island continent that has no land borders with adjacent countries. It also has responsibilities extending from the equatorial to polar regions, encompassing approximately one eighth of the worlds surface across a wide variety of geophysical conditions. Until very recently it also did not have neighboring countries with approved regional space weather warning centers, and had to exhibit a degree of self-reliance. After the solar cycle 23 maximum, a severe event service was developed to be ready for cycle 24. The service was aimed at technologies that had a high effect threshold for space weather events, with minimal response below the threshold but responses potentially damaging to the system above the threshold. These technologies are power grids, aviation GNSS precision approach, and spacecraft. The nature of what constitutes a severe event for these technologies in the national context will be described, with the services provided and stakeholder mitigation strategies.

Automatic recognition of complex magnetic regions on the Sun in SDO magnetogram images and prediction of flares: Techniques and results for the revised flare prediction program Flarecast

In the present paper, solar magnetograms provided by the Helioseismic and Magnetic Imager (HMI) on-board Solar Dynamics Observatory (SDO) spacecraft are used to identify active regions automatically by thresholding the line-of-sight component of the solar magnetic field. The flare potential of the regions is predicted by locating potential active regions with strong-gradient polarity inversion lines (SPILs) and estimating 18 physically relevant parameters of these regions. In particular, parameters of interest include the sum of north-south gradients, sum of east-west gradients, length of SPIL, and total integrated magnetic flux. For deterministic prediction of flares, analysis for thresholding of single parameters and different combinations, which include up to 4 parameters, are presented and compared. If the false alarm rate does not exceed 10% (20%), the probabilities for correct prediction of X-ray flares of class M and greater, M5 and greater, and X in the 24 h window are 71% (86%), 84% (96%), and 94% (100%), respectively. These probabilities are for the best 4-parameter technique found. A technique for probabilistic forecasting was also developed. These deterministic and probabilistic techniques will be implemented in a revised version of the flare warning program, Flarecast, which will be operational in the Australian Space Forecast Centre.