Сomparison of ion pressure variations derived from Cluster/CODIF and the combined Cluster/CODIF&RAPID data during prolonged dipolarizations in the near Earth magnetotail

2020 ◽  
Author(s):  
Andrey Malykhin ◽  
Elena Grigorenko ◽  
Elena Kronberg ◽  
Patrick Daly
Keyword(s):  
Energy Range ◽  
Energy Flux ◽  
Total Pressure ◽  
High Energy ◽  
Plasma Pressure ◽  
Energy Threshold ◽  
Superposed Epoch Analysis ◽  
Flux Increase ◽  
Epoch Analysis ◽  
Thermal Part

<p>Usually, for the plasma pressure estimation in the plasma sheet  ion observations in the energy range up to ~40 keV are used. However, the thermal part of the distribution function can pass beyond the high energy threshold of an instrument during active events like dipolarizations. In such cases the entire ion population is not measured and the ion pressure can be underestimated. We study this problem by using Cluster mission observations provided  by two instruments: thermal plasma instrument - CODIF (up to 38 keV) and suprathermal instrument - RAPID (from 40 up to 1500 keV). We analyzed 11 dipolarization events and showed that in all events the maximum of ion energy flux was shifted to high energy threshold of CODIF instrument. Simultaneously, the energy flux increase in suprathermal energy range was observed by RAPID. For H<sup>+</sup> and O<sup>+</sup> ion components we calculate the pressure of suprathermal population and showed that the total pressure estimated by using both CODIF and RAPID instruments at some intervals exceeds the pressure estimated only from CODIF data up to 5 times. The superposed epoch analysis applied to 11 dipolarization events from our data base showed that the total pressure of H<sup>+</sup> and O<sup>+</sup> ion components can be in 2-5 times underestimated in the course of dipolarization.</p>

scholarly journals Solar flares observed simultaneously with SphinX, GOES and RHESSI

2012 ◽  
Vol 8 (S294) ◽  
pp. 571-572 ◽  
Author(s):  
Tomasz Mrozek ◽  
Szymon Gburek ◽  
Marek Siarkowski ◽  
Barbara Sylwester ◽  
Janusz Sylwester ◽  
...  
Keyword(s):  
Energy Range ◽  
Solar Flares ◽  
Solar Minimum ◽  
Spectroscopic Analysis ◽  
High Energy ◽  
Pin Diode ◽  
X Rays ◽  
X Ray ◽  
Thermal Part ◽  
Silicon Pin Diode

AbstractIn February 2009, during recent deepest solar minimum, Polish Solar Photometer in X-rays (SphinX) begun observations of the Sun in the energy range of 1.2–15 keV. SphinX was almost 100 times more sensitive than GOES X-ray Sensors. The silicon PIN diode detectors used in the experiment were carefully calibrated on the ground using Synchrotron Radiation Source BESSY II. The SphinX energy range overlaps with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) energy range. The instrument provided us with observations of hundreds of very small flares and X-ray brightenings. We have chosen a group of solar flares observed simultaneously with GOES, SphinX and RHESSI and performed spectroscopic analysis of observations wherever possible. The analysis of thermal part of the spectra showed that SphinX is a very sensitive complementary observatory for RHESSI and GOES.

scholarly journals Semiannual Variation in radiation belts particle fluxes: Van Allen probes observations

2018 ◽  
Author(s):  
Facundo L. Poblet ◽  
Francisco Azpilicueta
Keyword(s):  
Energy Range ◽  
Ring Current ◽  
Electron Flux ◽  
Current System ◽  
Energy Levels ◽  
Superposed Epoch Analysis ◽  
Van Allen Probes ◽  
Semiannual Variation ◽  
Weather Parameters ◽  
Epoch Analysis

Abstract. The Semiannual Variation (SAV) is an annual pattern characterized by maxima around the equinoxes and minima near solstices observed in many space weather parameters. Several authors have studied this variation in the electron fluxes of the magnetosphere, focusing only in a few energy levels. In this investigation, Van Allen probes data are processed to extend SAV studies in electron fluxes of a wider energy range. A superposed epoch analysis was applied to data of the REPT and MagEIS instruments obtaining a clear semiannual pattern in the superposed year for L-shell values between 2.5 and 6.5. The Day Of Year (DOY) at which the highest electron flux values are detected near the September equinox coincide with the Russel & McPherron prediction. However, the DOY of the maximum expected close the March equinox occurs with a one month lag from the prediction of the accepted models. In addition, integrating over L-shell the annual DOY-L data with the semiannual pattern resulted in temporal curves that enabled to determine the energy range for which the SAV can be detected: from MeV to tens MeV energy values. Finally, an additional analysis of the fluxes of the Ring Current principal components (H+ and O+ ions) was performed, obtaining no evidence of a SAV on them. This result could indicate that the widely recognized semiannual pattern in the geomagnetic activity is related to a different current system.

scholarly journals An evaluation of space weather conditions for FORMOSAT-3 satellite anomalies

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Han-Wen Shen ◽  
Jih-Hong Shue ◽  
John Dombeck ◽  
Tsung-Ping Lee
Keyword(s):  
Geomagnetic Activity ◽  
Space Weather ◽  
Weather Conditions ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Low Earth Orbit ◽  
Occurrence Rate ◽  
Superposed Epoch Analysis ◽  
The Times ◽  
Epoch Analysis

AbstractThe variable electromagnetic environment in geospace plays a crucial role in influencing the occurrence probability of satellite anomalies. FORMOSAT-3 (FS3) is a Low-Earth-Orbit (LEO) mission, which consists of six identical microsatellites that orbit in the altitude of 700–800 km and with an inclination of 72°. The dependences of the FS3 satellite anomalies on space weather conditions have not been investigated in the past. With an exception of a small number of extremely high geomagnetic events, we find that the occurrence rate of the FS3 anomalies is negatively correlated with the level of geomagnetic activity. Moreover, the relationship between numbers of anomalies and sunspots is also anti-correlated. A superposed epoch analysis demonstrates that the intensity of galactic cosmic rays (GCR) is relatively high at the times of the anomalies. All these results infer that the FS3 anomalies predominantly occurred under the conditions associated with low solar activity. The possible main cause for the FS3 anomalies is high-energy trapped protons or GCR. In summary, this paper presents a statistical result that a satellite can be prone to suffer an anomaly under low solar or geomagnetic activity.

scholarly journals Solar Irradiance Variability Due to Solar Flares Observed in Lyman-Alpha Emission

Solar Physics ◽  
2021 ◽  
Vol 296 (3) ◽  
Author(s):  
Ryan O. Milligan
Keyword(s):  
Solar Flares ◽  
Solar Spectrum ◽  
Neutral Hydrogen ◽  
Solar Limb ◽  
High Background ◽  
Superposed Epoch Analysis ◽  
Lyman Alpha ◽  
Alpha Emission ◽  
Epoch Analysis ◽  
Very High

AbstractAs the Lyman-alpha (Ly$\upalpha $ α ) line of neutral hydrogen is the brightest emission line in the solar spectrum, detecting increases in irradiance due to solar flares at this wavelength can be challenging due to the very high background. Previous studies that have focused on the largest flares have shown that even these extreme cases generate enhancements in Ly$\upalpha $ α of only a few percent above the background. In this study, a superposed-epoch analysis was performed on ≈8500 flares greater than B1 class to determine the contribution that they make to changes in the solar EUV irradiance. Using the peak of the 1 – 8 Å X-ray emission as a fiducial time, the corresponding time series of 3123 B- and 4972 C-class flares observed in Ly$\upalpha $ α emission by the EUV Sensor on the Geostationary Operational Environmental Satellite 15 (GOES-15) were averaged to reduce background fluctuations and improve the flare signal. The summation of these weaker events showed that they produced a 0.1 – 0.3% enhancement to the solar Ly$\upalpha $ α irradiance on average. For comparison, the same technique was applied to 453 M- and 31 X-class flares, which resulted in a 1 – 4% increase in Ly$\upalpha $ α emission. Flares were also averaged with respect to their heliographic angle to investigate any potential center-to-limb variation. For each GOES class, the relative enhancement in Ly$\upalpha $ α at the flare peak was found to diminish for flares that occurred closer to the solar limb due to the opacity of the line and/or foreshortening of the footpoints. One modest event included in the study, a C6.6 flare, exhibited an unusually high increase in Ly$\upalpha $ α of 7% that may have been attributed to a failed filament eruption. Increases of this magnitude have hitherto only been associated with a small number of X-class flares.

Superposed Epoch Analysis of Nighttime Magnetic Perturbation Events Observed in Arctic Canada

2021 ◽  
Author(s):  
Mark J. Engebretson ◽  
Lidiya Y. Ahmed ◽  
Vyacheslav A. Pilipenko ◽  
Erik S. Steinmetz ◽  
Mark B. Moldwin ◽  
...  
Keyword(s):  
Arctic Canada ◽  
Magnetic Perturbation ◽  
Superposed Epoch Analysis ◽  
Epoch Analysis

scholarly journals Specific interplanetary conditions for CIR-, Sheath-, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis

2010 ◽  
Vol 28 (12) ◽  
pp. 2177-2186 ◽  
Author(s):  
Yu. I. Yermolaev ◽  
N. S. Nikolaeva ◽  
I. G. Lodkina ◽  
M. Yu. Yermolaev
Keyword(s):  
Large Scale ◽  
Geomagnetic Storms ◽  
Magnetic Cloud ◽  
Magnetic Storms ◽  
Main Phase ◽  
Corotating Interaction Region ◽  
Superposed Epoch Analysis ◽  
Epoch Analysis ◽  
Archive Data ◽  
Scale Types

Abstract. A comparison of specific interplanetary conditions for 798 magnetic storms with Dst <−50 nT during 1976–2000 was made on the basis of the OMNI archive data. We categorized various large-scale types of solar wind as interplanetary drivers of storms: corotating interaction region (CIR), Sheath, interplanetary CME (ICME) including both magnetic cloud (MC) and Ejecta, separately MC and Ejecta, and "Indeterminate" type. The data processing was carried out by the method of double superposed epoch analysis which uses two reference times (onset of storm and minimum of Dst index) and makes a re-scaling of the main phase of the storm in a such way that all storms have equal durations of the main phase in the new time reference frame. This method reproduced some well-known results and allowed us to obtain some new results. Specifically, obtained results demonstrate that (1) in accordance with "output/input" criteria the highest efficiency in generation of magnetic storms is observed for Sheath and the lowest one for MC, and (2) there are significant differences in the properties of MC and Ejecta and in their efficiencies.

scholarly journals PHEMTO: the polarimetric high energy modular telescope observatory

2021 ◽  
Author(s):  
P. Laurent ◽  
F. Acero ◽  
V. Beckmann ◽  
S. Brandt ◽  
F. Cangemi ◽  
...  
Keyword(s):  
Black Holes ◽  
Energy Range ◽  
High Performance ◽  
Angular Resolution ◽  
High Energy ◽  
Thermal Processes ◽  
Scientific Performance ◽  
X Ray ◽  
Measurement Capability ◽  
Better Than

AbstractBased upon dual focusing techniques, the Polarimetric High-Energy Modular Telescope Observatory (PHEMTO) is designed to have performance several orders of magnitude better than the present hard X-ray instruments, in the 1–600 keV energy range. This, together with its angular resolution of around one arcsecond, and its sensitive polarimetry measurement capability, will give PHEMTO the improvements in scientific performance needed for a mission in the 2050 era in order to study AGN, galactic black holes, neutrons stars, and supernovae. In addition, its high performance will enable the study of the non-thermal processes in galaxy clusters with an unprecedented accuracy.

scholarly journals Structure of the heliosheath from HSTOF energetic neutral atoms measurements

2018 ◽  
Vol 618 ◽  
pp. A26 ◽  
Author(s):  
A. Czechowski ◽  
M. Hilchenbach ◽  
K. C. Hsieh ◽  
M. Bzowski ◽  
S. Grzedzielski ◽  
...  
Keyword(s):  
Energy Range ◽  
Ecliptic Plane ◽  
High Energy ◽  
Neutral Atoms ◽  
Ion Distribution ◽  
Ion Density ◽  
Heliospheric Observatory ◽  
Energetic Neutral Atoms ◽  
Time Periods ◽  
Ecliptic Longitude

Context. From the year 1996 until now, High energy Suprathermal Time Of Flight sensor (HSTOF) on board Solar and Heliospheric Observatory (SOHO) has been measuring the heliospheric energetic neutral atoms (ENA) flux between ±17° from the ecliptic plane. At present it is the only ENA instrument with the energy range within that of Voyager LECP energetic ion measurements. The energetic ion density and thickness of the inner heliosheath along the Voyager 1 trajectory are now known, and the ENA flux in the HSTOF energy range coming from the Voyager 1 direction may be estimated. Aims. We use HSTOF ENA data and Voyager 1 energetic ion spectrum to compare the regions of the heliosheath observed by HSTOF and Voyager 1. Methods. We compared the HSTOF ENA flux data from the forward and flank sectors of the heliosphere observed in various time periods between the years 1996 and 2010 and calculated the predicted ENA flux from the Voyager 1 direction using the Voyager 1 LECP energetic ion spectrum and including the contributions of charge exchange with both neutral H and He atoms. Results. The ratio between the HSTOF ENA flux from the ecliptic longitude sector 210−300° (the LISM apex sector) for the period 1996−1997 to the estimated ENA flux from the Voyager 1 direction is ∼1.3, but decreases to ∼0.6 for the period 1996−2005 and ∼0.3 for 1998−2006. For the flank longitude sectors (120−210° and 300−30°), the ratio also tends to decrease with time from ∼0.6 for 1996−2005 to ∼0.2 for 2008−2010. We discuss implications of these results for the energetic ion distribution in the heliosheath and the structure of the heliosphere.

scholarly journals Recent Results from IceCube

2018 ◽  
Vol 46 ◽  
pp. 1860048 ◽  
Author(s):  
Dawn Williams
Keyword(s):  
Energy Range ◽  
Neutrino Oscillation ◽  
Atmospheric Neutrino ◽  
High Energy ◽  
South Pole ◽  
Neutrino Interactions ◽  
Diffuse Flux ◽  
High Energy Neutrinos

The IceCube Neutrino Observatory is a cubic kilometer detector located at the geographic South Pole. IceCube was designed to detect high-energy neutrinos from cosmic sources, and the DeepCore extension of IceCube enables the study of atmospheric neutrino interactions down to energies of a few GeV. IceCube has detected a diffuse flux of neutrinos in the energy range from 100 TeV to several PeV, the properties of which are inconsistent with an atmospheric origin, and has also published competitive limits on atmospheric neutrino oscillation parameters and other neutrino properties. This paper presents the latest results from IceCube and prospects for future upgrades and expansions of the detector.

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