Breathing of the Heliosphere

2021 ◽  
Vol 922 (2) ◽  
pp. 250
Author(s):  
Justyna M. Sokół ◽  
Maher A. Dayeh ◽  
Stephen A. Fuselier ◽  
Georgios Nicolaou ◽  
D. J. McComas ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Neutral Atom ◽  
Pressure Pulse ◽  
Dynamic Pressure ◽  
Ecliptic Plane ◽  
Abrupt Increase ◽  
Maximum Phase ◽  
Energetic Neutral Atom

Abstract In late 2016, the Interstellar Boundary Explorer (IBEX) observed an enhancement of hydrogen energetic neutral atom (ENA) flux in ∼20° south from the nose direction. This enhancement was a consequence of an abrupt increase of the solar wind (SW) dynamic pressure observed at 1 au in late 2014. In subsequent years, the increased flux of 4.3 keV ENAs was observed at higher latitudes filling in the heliosheath, in ENAs at lower energies, and the Ribbon flux. We observe that the rapid increase of SW pressure occurs every solar cycle (SC) from the beginning of the regular in situ SW measurements in the ecliptic plane. The SW pressure pulse happens about 4.7 yr from the beginning of each SC, it is during the maximum phase of solar activity, and repeats with a period of ∼10.2 yr. These repeating pulses of the SW pressure can cause periodic SC variations of the ENA production in the heliosheath. We follow McComas et al. results for the relation between SW pressure increase and ENA flux enhancement to investigate the periodic SW pressure increases and their consequences for the heliosphere. Our study of time delay between the cause (pressure pulse at 1 au) and the consequence (ENA enhancement) show that IBEX observed in 2009–2011 remnants of the SW pressure pulse that happened during the maximum of SC 23.

scholarly journals Energetic neutral atom response to solar wind dynamic pressure enhancements

2007 ◽  
Vol 112 (A9) ◽  
pp. n/a-n/a ◽  
Author(s):  
D.-Y. Lee ◽  
S. Ohtani ◽  
P. C. Brandt ◽  
L. R. Lyons
Keyword(s):  
Solar Wind ◽  
Neutral Atom ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Energetic Neutral Atom

Simulation of the Solar Wind Dynamic Pressure Increase in 2014 and Its Effect on Energetic Neutral Atom Fluxes from the Heliosphere

2018 ◽  
Vol 859 (2) ◽  
pp. 104 ◽  
Author(s):  
E. J. Zirnstein ◽  
J. Heerikhuisen ◽  
D. J. McComas ◽  
N. V. Pogorelov ◽  
D. B. Reisenfeld ◽  
...  
Keyword(s):  
Solar Wind ◽  
Neutral Atom ◽  
Dynamic Pressure ◽  
Pressure Increase ◽  
Solar Wind Dynamic Pressure ◽  
Energetic Neutral Atom

scholarly journals Multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an intense solar wind dynamic pressure pulse

2016 ◽  
Vol 34 (5) ◽  
pp. 493-509 ◽  
Author(s):  
Zheng Xiang ◽  
Binbin Ni ◽  
Chen Zhou ◽  
Zhengyang Zou ◽  
Xudong Gu ◽  
...  
Keyword(s):  
Solar Wind ◽  
Radiation Belt ◽  
Pressure Pulse ◽  
Electron Flux ◽  
Dynamic Pressure ◽  
Energetic Electron ◽  
Solar Wind Dynamic Pressure ◽  
Angle Scattering ◽  
Radiation Belt Electrons ◽  
Atmospheric Loss

<p><strong>Abstract.</strong> Radiation belt electron flux dropouts are a kind of drastic variation in the Earth's magnetosphere, understanding of which is of both scientific and societal importance. Using electron flux data from a group of 14 satellites, we report multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an event of intense solar wind dynamic pressure pulse. When the pulse occurred, magnetopause and atmospheric loss could take effect concurrently contributing to the electron flux dropout. Losses through the magnetopause were observed to be efficient and significant at <i>L</i> ≳ 5, owing to the magnetopause intrusion into <i>L</i> ∼ 6 and outward radial diffusion associated with sharp negative gradient in electron phase space density. Losses to the atmosphere were directly identified from the precipitating electron flux observations, for which pitch angle scattering by plasma waves could be mainly responsible. While the convection and substorm injections strongly enhanced the energetic electron fluxes up to hundreds of keV, they could delay other than avoid the occurrence of electron flux dropout at these energies. It is demonstrated that the pulse-time radiation belt electron flux dropout depends strongly on the specific interplanetary and magnetospheric conditions and that losses through the magnetopause and to the atmosphere and enhancements of substorm injection play an essential role in combination, which should be incorporated as a whole into future simulations for comprehending the nature of radiation belt electron flux dropouts.</p>

scholarly journals EFFECTS OF FAST AND SLOW SOLAR WIND ON THE ENERGETIC NEUTRAL ATOM (ENA) SPECTRA MEASURED BY THEINTERSTELLAR BOUNDARY EXPLORER(IBEX) AT THE HELIOSPHERIC POLES

2012 ◽  
Vol 749 (1) ◽  
pp. 50 ◽  
Author(s):  
M. A. Dayeh ◽  
D. J. McComas ◽  
F. Allegrini ◽  
B. De Majistre ◽  
M. I. Desai ◽  
...  
Keyword(s):  
Solar Wind ◽  
Neutral Atom ◽  
Slow Solar Wind ◽  
Energetic Neutral Atom

scholarly journals Quasi-periodic changes in the 3D solar anisotropy of Galactic cosmic rays for 1965–2014

2017 ◽  
Vol 609 ◽  
pp. A32 ◽  
Author(s):  
R. Modzelewska ◽  
M. V. Alania
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Ecliptic Plane ◽  
Galactic Cosmic Rays ◽  
Magnetic Cycle ◽  
The North ◽  
Solar Magnetic Cycle

Aims. We study features of the 3D solar anisotropy of Galactic cosmic rays (GCR) for 1965−2014 (almost five solar cycles, cycles 20−24). We analyze the 27-day variations of the 2D GCR anisotropy in the ecliptic plane and the north-south anisotropy normal to the ecliptic plane. We study the dependence of the 27-day variation of the 3D GCR anisotropy on the solar cycle and solar magnetic cycle. We demonstrate that the 27-day variations of the GCR intensity and anisotropy can be used as an important tool to study solar wind, solar activity, and heliosphere. Methods. We used the components Ar, Aϕ and At of the 3D GCR anisotropy that were found based on hourly data of neutron monitors (NMs) and muon telescopes (MTs) using the harmonic analyses and spectrographic methods. We corrected the 2D diurnal (~24-h) variation of the GCR intensity for the influence of the Earth magnetic field. We derived the north-south component of the GCR anisotropy based on the GG index, which is calculated as the difference in GCR intensities of the Nagoya multidirectional MTs. Results. We show that the behavior of the 27-day variation of the 3D anisotropy verifies a stable long-lived active heliolongitude on the Sun. This illustrates the usefulness of the 27-day variation of the GCR anisotropy as a unique proxy to study solar wind, solar activity, and heliosphere. We distinguish a tendency of the 22-yr changes in amplitude of the 27-day variation of the 2D anisotropy that is connected with the solar magnetic cycle. We demonstrate that the amplitudes of the 27-day variation of the north-south component of the anisotropy vary with the 11-yr solar cycle, but a dependence of the solar magnetic polarity can hardly be recognized. We show that the 27-day recurrences of the GG index and the At component are highly positively correlated, and both are highly correlated with the By component of the heliospheric magnetic field.

scholarly journals Assessing the Performance of EUHFORIA Modeling the Background Solar Wind

Solar Physics ◽  
2019 ◽  
Vol 294 (12) ◽  
Author(s):  
Jürgen Hinterreiter ◽  
Jasmina Magdalenic ◽  
Manuela Temmer ◽  
Christine Verbeke ◽  
Immanuel Christopher Jebaraj ◽  
...  
Keyword(s):  
Time Series ◽  
Solar Wind ◽  
Solar Activity ◽  
Coronal Holes ◽  
High Solar Activity ◽  
Time Interval ◽  
Input Parameters ◽  
First Results ◽  
Combined Time Series

AbstractIn order to address the growing need for more accurate space-weather predictions, a new model named (EUropean Heliospheric FORecasting Information Asset) was recently developed. We present the first results of the performance assessment for the solar-wind modeling with and identify possible limitations of its present setup. Using the basic 1.0.4 model setup with the default input parameters, we modeled background solar wind (no coronal mass ejections) and compared the obtained results with Advanced Composition Explorer (ACE) in-situ measurements. For the purposes of statistical study we developed a technique of combining daily runs into continuous time series. The combined time series were derived for the years 2008 (low solar activity) and 2012 (high solar activity), from which in-situ speed and density profiles were extracted. We find for the low-activity phase a better match between model results and observations compared to the high-activity time interval considered. The quality of the modeled solar-wind parameters is found to be rather variable. Therefore, to better understand the results obtained we also qualitatively inspected characteristics of coronal holes, i.e. the sources of the studied fast streams. We discuss how different characteristics of the coronal holes and input parameters to influence the modeled fast solar wind, and suggest possibilities for the improvement of the model.

Dusk side clockwise vortex generation and aurora intensity decrease after Solar Wind Dynamic Pressure Decrease

2021 ◽  
Author(s):  
Jinyan Zhao ◽  
Quanqi Shi ◽  
Anmin Tian ◽  
Ruilong Guo ◽  
Xiao-Chen Shen
Keyword(s):  
Solar Wind ◽  
Pressure Pulse ◽  
Dynamic Pressure ◽  
Simulation Method ◽  
Solar Wind Dynamic Pressure ◽  
Ionospheric Currents ◽  
The Earth ◽  
Sudden Decrease ◽  
Pulse Arrival ◽  
Observation Results

&lt;p&gt;A solar wind dynamic pressure increase/decrease leads to the compression/expansion of the Earth&amp;#8217;s magnetosphere. In response, field-aligned currents, which are carried by precipitating or escaping plasma particles, are generated in the magnetosphere and in lead to variations in the auroral intensity. In this study, we investigate magnetospheric and ionospheric responses (including magnetospheric plasma vortex, ionospheric currents and aurorae) to a sudden decrease in solar wind dynamic pressure (SW P&lt;sub&gt;dyn&lt;/sub&gt;), which is critical for further understanding of the solar wind-magnetosphere-ionosphere coupling. We focused on a SW P&lt;sub&gt;dyn&lt;/sub&gt; decrease event that monitored by OMNI. A counter-clockwise plasma vortex was generated in the dusk side magnetosphere uncovered by using MHD simulation method and a clockwise equivalent ionospheric currents (EIC) vortex was generated in the dusk side ionosphere within about ten minutes after the pressure pulse arrival. Simultaneously, the observation results of Spherical Elementary Currents (SECs) showed that the EIC vortex region is dominated by downward field-aligned currents and the ground-based All-Sky Imager (ASI) observations in the vicinity of this EIC vortex showed that the aurorae diminished. These observations are consistent with the scenario proposed by Shi et al. (2014) that flow vortices in the magnetosphere generated by SW P&lt;sub&gt;dyn&lt;/sub&gt; sudden decrease carry downward field-aligned currents into the dusk side ionosphere, generating ionospheric current vortex and thereby modulating auroral activity on the dusk side.&lt;/p&gt;

scholarly journals Transitions between states of magnetotail–ionosphere coupling and the role of solar wind dynamic pressure: the 25 July 2004 interplanetary CME case

2015 ◽  
Vol 33 (4) ◽  
pp. 427-436 ◽  
Author(s):  
P. E. Sandholt ◽  
C. J. Farrugia ◽  
W. F. Denig
Keyword(s):  
Solar Wind ◽  
Current System ◽  
Dynamic Pressure ◽  
Auroral Oval ◽  
Abrupt Increase ◽  
Southern Boundary ◽  
Latitude Range ◽  
Interplanetary Coronal Mass Ejection ◽  
Substorm Activity ◽  
Braking Phase

Abstract. In a case study, we investigate transitions between fundamental magnetosphere–ionosphere (M-I) coupling modes during storm-time conditions (SYM-H between −100 and −160 nT) driven by an interplanetary coronal mass ejection (ICME). We combine observations from the near tail, at geostationary altitude (GOES-10), and electrojet activities across the auroral oval at postnoon-to-dusk and midnight. After an interval of strong westward electrojet (WEJ) activity, a 3 h long state of attenuated/quenched WEJ activity was initiated by abrupt drops in the solar wind density and dynamic pressure. The attenuated substorm activity consisted of brief phases of magnetic field perturbation and electron flux decrease at GOES-10 near midnight and moderately strong conjugate events of WEJ enhancements at the southern boundary of the oval, as well as a series of very strong eastward electrojet (EEJ) events at dusk, during a phase of enhanced ring current evolution, i.e., enhanced SYM-H deflection within −120 to −150 nT. Each of these M-I coupling events was preceded by poleward boundary intensifications and auroral streamers at higher oval latitudes. We identify this mode of attenuated substorm activity as being due to a magnetotail state characterized by bursty reconnection and bursty bulk flows/dipolarization fronts (multiple current wedgelets) with associated injection dynamo in the near tail, in their braking phase. The latter process is associated with activations of the Bostrøm type II (meridional) current system. A transition to the next state of M-I coupling, when a full substorm expansion took place, was triggered by an abrupt increase of the ICME dynamic pressure from 1 to 5 nPa. The brief field deflection events at GOES-10 were then replaced by a 20 min long interval of extreme field stretching (Bz approaching 5 nT and Bx ≈ 100 nT) followed by a major dipolarization (Δ Bz ≈ 100 nT). In the ionosphere the latter stage appeared as a "full-size" stepwise poleward expansion of the WEJ. It thus appears that the ICME passage led to fundamentally different M-I coupling states corresponding to different levels of dynamic pressure (Pdyn) under otherwise very similar ICME conditions. Full WEJ activity, covering a wide latitude range across the auroral oval in the midnight sector, was attenuated by the abrupt dynamic pressure decrease and resumed after the subsequent abrupt increase.

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