scholarly journals The study of the strongest solar event on a minimum of the 24th solar cycle

2021 ◽  
Vol 2145 (1) ◽  
pp. 012012
Author(s):  
D Peldon ◽  
K Tshering ◽  
B Gurung ◽  
T Khumlumlert ◽  
N Aiemsa-Ad
Keyword(s):  
Solar Cycle ◽  
Solar Flare ◽  
Numerical Technique ◽  
Solar Energetic Particle ◽  
High Energy ◽  
Western Hemisphere ◽  
Injection Time ◽  
Solar Event ◽  
The Earth ◽  
Spacecraft Data

Abstract The strongest solar flares of the 24th solar cycle erupted on September 6, 2017, and it was the 8th strongest solar flare recorded since 1996. This extreme solar flare occurred at the minimum of the 24th solar cycle. The active region is located in the Western Hemisphere and produced the violent explosion of class X9.3 and X2.2 on September 6, X1.3 on September 7, and X8.2 on September 10, 2017. The injection duration of the solar energetic particles of the solar event was 17 minutes. All data for this solar event was collected from the Advanced Composition Explorer and simulated for particles’ motion using the transport equation and solved by the numerical technique. We obtained the injection time of the solar energetic particle propagation by comparing fitting between the simulation results and the spacecraft data. Injection time taken by high-energy particles to travel from the Sun to the Earth was found to be in the range of 39 to 743 minutes. At the peak of this solar flare, the coronal mass ejection was detected, which increased the injection time. The Kp-index of this solar flare was 4; thus, there was no effect on the Earth. The Kp-index value increased to 8 on September 7-8, 2017, due to another solar event from the same sunspot region, indicating the effect of solar flare and CME, which resulted in the appearance of aurora.

scholarly journals Forecasting Solar Energetic Particle Events and Associated False Alarms

2017 ◽  
Vol 13 (S335) ◽  
pp. 324-327
Author(s):  
Bill Swalwell ◽  
Silvia Dalla ◽  
Robert Walsh
Keyword(s):  
Energetic Particle ◽  
Solar Energetic Particle ◽  
High Energy ◽  
False Alarms ◽  
Solar Event ◽  
Solar Energetic Particle Events ◽  
Two Factors ◽  
Very High Energy ◽  
Solar Events ◽  
Very High

AbstractBecause of the significant dangers they pose, accurate forecasting of Solar Energetic Particle (SEP) events is vital. Whilst it has long been known that SEP-production is associated with high-energy solar events, forecasting algorithms based upon the observation of these types of solar event suffer from high false alarm rates. Here we analyse the parameters of 4 very high energy solar events which were false alarms, with a view to reaching an understanding as to why SEPs were not detected at Earth. We find that in each case at least two factors were present which have been shown to be detrimental to SEP production.

scholarly journals Forecasting Solar Energetic Particle (SEP) events with Flare X-ray peak ratios

2018 ◽  
Vol 8 ◽  
pp. A47 ◽  
Author(s):  
Stephen W. Kahler ◽  
Alan. G. Ling
Keyword(s):  
Solar Flare ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Western Hemisphere ◽  
X Rays ◽  
X Ray ◽  
Forecasting Methods ◽  
Versus Peak

Solar flare X-ray peak fluxes and fluences in the 0.1–0.8 nm band are often used in models to forecast solar energetic particle (SEP) events. Garcia (2004) [Forecasting methods for occurrence and magnitude of proton storms with solar soft X rays, Space Weather, 2, S02002, 2004] used ratios of the 0.05–0.4 and 0.1–0.8 nm bands of the X-ray instrument on the GOES spacecraft to plot inferred peak flare temperatures versus peak 0.1–0.8 nm fluxes for flares from 1988 to 2002. Flares associated with E > 10 MeV SEP events of >10 proton flux units (pfu) had statistically lower peak temperatures than those without SEP events and therefore offered a possible empirical forecasting tool for SEP events. We review the soft and hard X-ray flare spectral variations as SEP event forecast tools and repeat Garcia’s work for the period 1998–2016, comparing both the peak ratios and the ratios of the preceding 0.05–0.4 nm peak fluxes to the later 0.1–0.8 nm peak fluxes of flares >M3 to the occurrence of associated SEP events. We divide the events into eastern and western hemisphere sources and compare both small (1.2–10 pfu) and large (≥300 pfu) SEP events with those of >10 pfu. In the western hemisphere X-ray peak ratios are statistically lower for >10 pfu SEP events than for non-SEP events and are even lower for the large (>300 pfu) events. The small SEP events, however, are not distinguished from the non-SEP events. We discuss the possible connections between the flare X-ray peak ratios and associated coronal mass ejections that are presumed to be the sources of the SEPs.

scholarly journals Solar Gamma Rays and their Correlation with Space and Ground-Based Observations

1968 ◽  
Vol 1 ◽  
pp. 544-546
Author(s):  
G.G. Fazio
Keyword(s):  
Solar Cycle ◽  
Solar Flare ◽  
Gamma Rays ◽  
Solar Flares ◽  
Radiation Spectrum ◽  
High Energy ◽  
Electromagnetic Spectrum ◽  
Major Flare ◽  
Integral Energy ◽  
Flare Model

Thus far, only two experiments have detected solar γ-radiation with energy significantly greater than 200 keV. In both events the γ-ray emission occurred during a solar flare. The first observation was in 1958 by Peterson and Winckler (1959), who recorded a burst of radiation that occurred in less than 18 sec from a class-2 solar flare. The radiation spectrum peaked in the 200- to 500-keV region. Recently, Cline et al. (1967) recorded in the OGO-3 satellite three rapid γ-ray bursts in the 80-keV to 1-MeV energy range and measured the integral energy spectrum. The measurements were made on July 7, 1966, during the first high-intensity flare (importance 3) of the new solar cycle. Many attempts have been made to measure higher energy γ-radiation from the quiet Sun and from solar flares, but no flux has been detected; this is primarily due to the fact that no high-energy γ-ray detectors have viewed a major solar flare during the maximum of the optical or microwave burst. However, theoretical estimates of the flux of solar γ-rays, based on a simple flare model, indicate a readily detectable flux from a major flare even to photon energies of 100 MeV. It is therefore important that experiments be performed during the coming maximum of the solar cycle to investigate this region of the electromagnetic spectrum.

scholarly journals Distinguishing the Sources

2021 ◽  
pp. 49-69
Author(s):  
Donald V. Reames
Keyword(s):  
Magnetic Field ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Active Regions ◽  
High Energy ◽  
Injection Time ◽  
Closed Loops ◽  
Compact Source ◽  
Time Profiles ◽  
Onset Timing

AbstractOur discussion of history has covered many of the observations that have led to the ideas of acceleration by shock waves or by magnetic reconnection in gradual and impulsive solar energetic particle (SEP) events, respectively. We now present other compelling observations, including onset timing, SEP-shock correlations, injection time profiles, high-energy spectral knees, e/p ratios, and intensity dropouts caused by a compact source, that have helped clarify these acceleration mechanisms and sources. However, some of the newest evidence now comes from source-plasma temperatures. In this and the next two chapters, we will find that impulsive events come from solar active regions at ≈ 3 MK, controlling ionization states Q, hence A/Q, and, in most gradual events, shocks accelerate ambient coronal material from ≤1.6 MK. When SEPs are trapped on closed loops they supply the energy for flares. In addition to helping to define their own origin, SEPs also probe the structure of the interplanetary magnetic field.

Characteristics of source location and solar cycle distribution of the strong solar proton events (≥ 1000 pfu) from 1976 to 2018

2021 ◽  
Author(s):  
Gui-Ming Le ◽  
Ming-Xian Zhao ◽  
Qi Li ◽  
Gui-Ang Liu ◽  
Tian Mao ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Ground Level ◽  
Solar Proton ◽  
Western Hemisphere ◽  
Poor Correlation ◽  
The Sun ◽  
The Earth ◽  
Solar Proton Events ◽  
Northern And Southern Hemispheres

Abstract We studied the source locations and solar cycle distribution of strong solar proton events (≥ 1000 pfu) measured at the Earth from 1976 to 2018. There were 43 strong solar proton events (SPEs) during this period. 27.9 per cent of the strong SPEs were ground level enhancement (GLE) events. We detect more strong SPEs coming from the western hemisphere. The strong SPEs were distributed in the region of [E90-W90], extreme SPEs (≥10000 pfu) appeared within the longitudinal area from E30 to W75, while the SPEs with peak fluxes ≥ 20000 pfu concentrated in the range from E30 to W30 and were always accompanied by super geomagnetic storms (Dst ≤−250 nT). The northern and southern hemispheres of the Sun have 23 and 20 strong SPEs, respectively. The ranges S0–S19 and N0–N19 have 13 and 11 strong SPEs, respectively. S20–S45 and N20–N45 have 7 and 12 strong SPEs, respectively, indicating that the N-S asymmetry of strong SPEs mainly occurred in the areas with a latitude greater than 20○ of the two hemispheres of the Sun. The statistical results showed that 48.8 per cent, 51.2 per cent, and 76.7 per cent of the strong SPEs appeared during the rising phase, declining phase, and in the period from two years before to the three years after the solar maximum, respectively. The number of strong SPEs during a solar cycle has a poor correlation with the solar cycle size.

scholarly journals Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

2011 ◽  
Vol 11 (10) ◽  
pp. 5045-5077 ◽  
Author(s):  
K. Semeniuk ◽  
V. I. Fomichev ◽  
J. C. McConnell ◽  
C. Fu ◽  
S. M. L. Melo ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Radiative Forcing ◽  
Climate Model ◽  
Middle Atmosphere ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Particle Precipitation ◽  
Solar Cycle Variation ◽  
Cycle Variation ◽  
The Impact

Abstract. The impact of NOx and HOx production by three types of energetic particle precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

High Energy Particle Spectrometer for ESA Lagrange mission

2021 ◽  
Author(s):  
Wojtek Hajdas ◽  
Radoslaw Marcinkowski ◽  
Hualin Xiao ◽  
Ronny Kramert
Keyword(s):  
Solar Energetic Particle ◽  
Heavy Ion ◽  
High Energy ◽  
High Energy Particle ◽  
Energy Particle ◽  
Detection Systems ◽  
Parker Spiral ◽  
Final Design ◽  
Radiation Tolerant

<p>The LGR High Energy Particle Spectrometer HEPS for the ESA Lagrange mission belongs to the satellite in-situ instrument suite. The satellite will be placed at the Lagrange point L5 for space weather measurements and real-time observations and alerts. The HEPS instrument with its six detector subsystems will enable the detecting of electrons, protons, and heavy ions at high flux conditions during Solar Energetic Particle Events. The electron and proton detection systems rely on standard telescope techniques covering energy ranges from 100 keV to 15 MeV and 3 MeV to 1 GeV respectively. Two sets of telescopes will be installed facing opposite directions along the Parker spiral. Additional detector with a wide angular range will enable measurements of angular distributions of particles traveling towards the satellite from the Sun. The HEPS heavy-ion telescope HIT represents a new design utilizing a set of scintillators and SiPM light converters. HIT electronics is equipped with a dedicated radiation-tolerant ASIC optimized for low power use and fast signal detections. The first model of HIT was developed and verified for spectroscopic measurements and ion identification. We report on test measurements as well as Monte Carlo simulations of the whole instrument. Results will be discussed and implications on the final design of the instrument provided.</p>

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