Found 114 results
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V
Authors: Vainio Rami, önni Arttu, Battarbee Markus, Koskinen Hannu E. J., Afanasiev Alexandr, et al.
Title: A semi-analytical foreshock model for energetic storm particle events inside 1 AU
Abstract:

We have constructed a semi-analytical model of the energetic-ion foreshock of a CME-driven coronal/interplanetary shock wave responsible for the acceleration of large solar energetic particle (SEP) events. The model is based on the analytical model of diffusive shock acceleration of Bell (1978), appended with a temporal dependence of the cut-off momentum of the energetic particles accelerated at the shock, derived from the theory. Parameters of the model are re-calibrated using a fully time-dependent self-consistent simulation model of the coupled particle acceleration and Alfvén-wave generation upstream of the shock. Our results show that analytical estimates of the cut-off energy resulting from the simplified theory and frequently used in SEP modelling are overestimating the cut-off . . .
Date: 02/2014 Publisher: Journal of Space Weather and Space Climate Pages: A08 DOI: 10.1051/swsc/2014005 Available at: http://www.swsc-journal.org/10.1051/swsc/2014005http://www.swsc-journal.org/10.1051/swsc/2014005/pdf
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Authors: Velli Marco, Lionello Roberto, Linker Jon A., and ć Zoran
Title: CORONAL PLUMES IN THE FAST SOLAR WIND
Abstract:

The expansion of a coronal hole filled with a discrete number of higher density coronal plumes is simulated using a time-dependent two-dimensional code. A solar wind model including an exponential coronal heating function and a flux of Alfvén waves propagating both inside and outside the structures is taken as a basic state. Different plasma plume profiles are obtained by using different scale heights for the heating rates. Remote sensing and solar wind in situ observations are used to constrain the parameter range of the study. Time dependence due to plume ignition and disappearance is also discussed. Velocity differences of the order of ~50 km s-1, such as those found in microstreams in the high-speed solar wind, may be easily explained by slightly different heat depositio. . .
Date: 07/2011 Publisher: The Astrophysical Journal Pages: 32 DOI: 10.1088/0004-637X/736/1/32 Available at: http://stacks.iop.org/0004-637X/736/i=1/a=32?key=crossref.9f21641f557225a36ce23f05fa1256f6http://stacks.iop.org/0004-637X/736/i=1/a=32/pdf
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Authors: Venzmer M. S., and Bothmer V.
Title: Solar-wind predictions for the Parker Solar Probeorbit
Abstract:

Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission will be humanitys first in situ exploration of the solar corona with closest perihelia at 9.86 solar radii (R) distance to the Sun. It will help answer hitherto unresolved questions on the heating of the solar corona and the source and acceleration of the solar wind and solar energetic particles. The scope of this study is to model the solar-wind environment for PSPs unprecedented distances in its prime mission phase during the years 2018 to 2025. The study is performed within the Coronagraphic German And US SolarProbePlus Survey (CGAUSS) which is the German contribution to the PSP mission as part of the Wide-field Imager for Solar PRobe. Aim. We present an empirical solar-wind model for the inner hel. . .
Date: 03/2018 Publisher: Astronomy & Astrophysics Pages: A36 DOI: 10.1051/0004-6361/201731831 Available at: https://www.aanda.org/10.1051/0004-6361/201731831https://www.aanda.org/10.1051/0004-6361/201731831/pdf
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Authors: Verscharen Daniel, Chandran Benjamin D. G., Jeong Seong-Yeop, Salem Chadi S., Pulupa Marc P., et al.
Title: Self-induced Scattering of Strahl Electrons in the Solar Wind
Abstract:

We investigate the scattering of strahl electrons by microinstabilities as a mechanism for creating the electron halo in the solar wind. We develop a mathematical framework for the description of electron-driven microinstabilities and discuss the associated physical mechanisms. We find that an instability of the oblique fast-magnetosonic/whistler (FM/W) mode is the best candidate for a microinstability that scatters strahl electrons into the halo. We derive approximate analytic expressions for the FM/W instability threshold in two different β c regimes, where β c is the ratio of the core electrons’ thermal pressure to the magnetic pressure, and confirm the accuracy of these thresholds through comparison with numerical solutions to the hot-plasma dispersion rela. . .
Date: 12/2019 Publisher: The Astrophysical Journal Pages: 136 DOI: 10.3847/1538-4357/ab4c30 Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab4c30https://iopscience.iop.org/article/10.3847/1538-4357/ab4c30/
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W
Authors: Wicks Robert T., Matteini Lorenzo, Horbury Timothy S., Hellinger Petr, and Roberts Aaron
Title: AIP Conference ProceedingsTemperature anisotropy instabilities; combining plasma and magnetic field data at different distances from the Sun
Abstract:

We present a new data analysis method enabling the observation of magnetic field fluctuations associated with temperature anisotropy instabilities using the Ulysses spacecraft. The movement of the spacecraft away from the Sun causes the observed plasma conditions, turbulent fluctuation amplitude, magnetic field strength and important physical scales to change. We normalize wavelet power spectra of the magnetic field using local values for the proton gyroscale and large scale magnetic field fluctuation amplitude to remove the effects of varying heliocentric distance. We recover the enhancement of magnetic fluctuations where temperature anisotropy instability growth rates are large, as seen by previous studies in the ecliptic at 1 AU. This method can be applied to any spacecraft data that. . .
Date: 07/2013 Publisher: AIP DOI: 10.1063/1.4811048 Available at: http://aip.scitation.org/doi/abs/10.1063/1.4811048
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Authors: Wilson Lynn B., Chen Li-Jen, Wang Shan, Schwartz Steven J., Turner Drew L., et al.
Title: Electron Energy Partition across Interplanetary Shocks. II. Statistics
Abstract:

A statistical analysis of 15,210 electron velocity distribution function (VDF) fits, observed within ±2 hr of 52 interplanetary (IP) shocks by the Wind spacecraft near 1 au, is presented. This is the second in a three-part series on electron VDFs near IP shocks. The electron velocity moment statistics for the dense, low-energy core, tenuous, hot halo, and field-aligned beam/strahl are a statistically significant list of values illustrated with both histograms and tabular lists for reference and baselines in future work. Given the large statistics in this investigation, the beam/strahl fit results in the upstream are now the most comprehensive attempt to parameterize the beam/strahl electron velocity moments in the ambient solar wind. The median density, temperature, beta, and temperatu. . .
Date: 12/2019 Publisher: The Astrophysical Journal Supplement Series Pages: 24 DOI: 10.3847/1538-4365/ab5445 Available at: https://iopscience.iop.org/article/10.3847/1538-4365/ab5445
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Authors: Winslow Reka M., Schwadron Nathan A., Lugaz é, Guo Jingnan, Joyce Colin J., et al.
Title: Opening a Window on ICME-driven GCR Modulation in the Inner Solar System
Abstract:

Interplanetary coronal mass ejections (ICMEs) often cause Forbush decreases (Fds) in the flux of galactic cosmic rays (GCRs). We investigate how a single ICME, launched from the Sun on 2014 February 12, affected GCR fluxes at Mercury, Earth, and Mars. We use GCR observations from MESSENGER at Mercury, ACE/LRO at the Earth/Moon, and MSL at Mars. We find that Fds are steeper and deeper closer to the Sun, and that the magnitude of the magnetic field in the ICME magnetic ejecta as well as the “strength” of the ICME sheath both play a large role in modulating the depth of the Fd. Based on our results, we hypothesize that (1) the Fd size decreases exponentially with heliocentric distance, and (2) that two-step Fds are more common closer to the Sun. Both hypotheses will be directly verifia. . .
Date: 04/2018 Publisher: The Astrophysical Journal Pages: 139 DOI: 10.3847/1538-4357/aab098 Available at: http://stacks.iop.org/0004-637X/856/i=2/a=139?key=crossref.287f3cbc519cdfae455bd8b9d0a9351a
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Authors: Witze Alexandra
Title: Death-defying NASA mission will make humanity’s closest approach to the Sun
Abstract:

The Parker Solar Probe will dive into the sizzling solar corona to explore its mysteries.


Date: 07/2018 Publisher: Nature Pages: 452 - 453 DOI: 10.1038/d41586-018-05741-6 Available at: http://www.nature.com/articles/d41586-018-05741-6http://www.nature.com/articles/d41586-018-05741-6.pdfhttp://www.nature.com/articles/d41586-018-05741-6http://www.nature.com/articles/d41586-018-05741-6.pdf
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Authors: Witze Alexandra
Title: Sun-bombing spacecraft uncovers secrets of the solar wind
Abstract:

Surprise magnetic reversals and an unexpectedly fast rotating wind mark the first findings from NASA's Parker Solar Probe.


Date: 12/2019 Publisher: Nature Pages: 15 - 16 DOI: 10.1038/d41586-019-03684-0 Available at: http://www.nature.com/articles/d41586-019-03684-0http://www.nature.com/articles/d41586-019-03684-0.pdfhttp://www.nature.com/articles/d41586-019-03684-0.pdfhttp://www.nature.com/articles/d41586-019-03684-0
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X
Authors: Xiong Ming, Davies Jackie A., Feng Xueshang, Li Bo, Yang Liping, et al.
Title: Prospective White-light Imaging and In Situ Measurements of Quiescent Large-scale Solar-wind Streams from the Parker Solar Probe and Solar Orbiter
Abstract:

Deep-space exploration of the inner heliosphere is in an unprecedented golden age, with the recent and forthcoming launches of the Parker Solar Probe (PSP) and Solar Orbiter (SolO) missions, respectively. In order to both predict and understand the prospective observations by PSP and SolO, we perform forward MHD modeling of the 3D inner heliosphere at solar minimum, and synthesize the white-light (WL) emission that would result from Thomson scattering of sunlight from the coronal and heliospheric plasmas. Both solar rotation and spacecraft trajectory should be considered when reconstructing quiescent large-scale solar-wind streams from PSP and SolO WL observations. When transformed from a static coordinate system into a corotating one, the elliptical orbit of PSP becomes a multiwinding . . .
Date: 12/2018 Publisher: The Astrophysical Journal Pages: 137 DOI: 10.3847/1538-4357/aae978 Available at: http://stacks.iop.org/0004-637X/868/i=2/a=137?key=crossref.fe473eb9a278d1ea105f9203808e2eab
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Y
Authors: Yoon P. H., Seough J., Salem C. S., and Klein K. G.
Title: Solar Wind Temperature Isotropy
Abstract:

Reliable models of the solar wind in the near-Earth space environment may constrain conditions close to the Sun. This is relevant to NASA's contemporary innerheliospheric mission Parker Solar Probe. Among the outstanding issues is how to explain the solar wind temperature isotropy. Perpendicular and parallel proton and electron temperatures near 1 AU are theoretically predicted to be unequal, but in situ observations show quasi-isotropy sufficiently below the instability threshold condition. This has not been satisfactorily explained. The present Letter shows that the dynamical coupling of electrons and protons via collisional processes and instabilities may contribute toward the resolution of this problem.


Date: 10/2019 Publisher: Physical Review Letters DOI: 10.1103/PhysRevLett.123.145101 Available at: https://link.aps.org/doi/10.1103/PhysRevLett.123.145101http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.123.145101/fulltexthttps://link.aps.org/article/10.1103/PhysRevLett.123.145101
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Authors: Yoon Peter H., Hwang Junga, Kim Hyangpyo, and Seough Jungjoon
Title: Quasi Thermal Noise Spectroscopy for Van Allen Probes
Abstract:

Quasi thermal fluctuations in the Langmuir/upper-hybrid frequency range are pervasively observed in space plasmas including the radiation belt and the ring current region of inner magnetosphere as well as the solar wind. The quasi thermal noise spectroscopy may be employed in order to determine the electron density and temperature as well as to diagnose the properties of energetic electrons when direct measurements are not available. However, when employing the technique, one must carefully take the spacecraft orientation into account. The present paper takes the upper-hybrid and multiple harmonic—or (n + 1/2)fce—emissions measured by the Van Allen Probes as an example in order to illustrate how the spacecraft antenna geometrical factor can be incorporated into the theore. . .
Date: 04/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026460 Available at: https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JA026460
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Authors: Yoon Peter H., Hwang Junga, ópez Rodrigo A., Kim Sunjung, and Lee Jaejin
Title: Electromagnetic Thermal Noise in Upper-Hybrid Frequency Range
Abstract:

The inner magnetosphere including the radiation belt and ring current environment is replete with high-frequency fluctuations with peak intensity occurring near upper-hybrid frequency and/or multiple harmonic electron cyclotron frequencies above and below the upper-hybrid frequency. Past and contemporary spacecraft missions, including the Van Allen Probes, were designed to detect the electric field spectrum only for these high-frequency fluctuations. Making use of the recently formulated generalized theory of electromagnetic spontaneous emission in thermal magnetized plasmas, it is shown that upper-hybrid/multiple harmonic electron cyclotron emissions are characterized by a significant magnetic field component, even in the high-frequency regime. Such a prediction may potentially be test. . .
Date: 07/2018 Publisher: Journal of Geophysical Research: Space Physics Pages: 5356 - 5363 DOI: 10.1029/2018JA025459 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1029/2018JA025459/fullpdf
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Z
Authors: ZALDIVAR J
Title: Long-term simulation of main biogeochemical events in a coastal lagoon: Sacca Di Goro (Northern Adriatic Coast, Italy)
Abstract:

A biogeochemical model for the Sacca di Goro Lagoon has been developed and partially validated with field data from 1989 to 1998. The model considers the nutrient cycles in the water column as well as in the sediments. Furthermore, phytoplankton, zooplankton, and Ulva sp. dynamics, as well as shellfish farming, are taken into account. Due to the recent anoxic crises in the lagoon, the dynamic of oxygen has also been simulated. The actual version of the model is a 0D with input fluxes from the watershed and exchange with the Northern Adriatic Sea. Nutrients from the watershed, wet and dry deposition, temperature, light intensity, wind speed and shellfish production are considered as forcing functions. The results show that the model is able to capture the essential dynamics of the lagoon. . .
Date: 11/2003 Publisher: Continental Shelf Research Pages: 1847 - 1875 DOI: 10.1016/j.csr.2003.01.001 Available at: http://linkinghub.elsevier.com/retrieve/pii/S027843430300150Xhttp://api.elsevier.com/content/article/PII:S0278-4343(03)00150-X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0278-4343(03)00150-X?httpAccept=text/plain
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