Results 41 to 50 of about 1,446 (180)

An Empirical Model of a Polar Coronal Hole at Solar Minimum

The Astrophysical Journal, 1999
We present a comprehensive and self-consistent empirical model for several plasma parameters in the extended solar corona above a polar coronal hole. The model is derived from observations with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) during the period between 1996 November and 1997 April.
CRANMER S. R., KOHL J. L., NOCI G., ANTONUCCI E., TONDELLO G., HUBER M. C. E., STRACHAN L., PANASYUK A. V., GARDNER L. D., ROMOLI M., FINESCHI S., DOBRZYCKA D., RAYMOND J. C., NICOLOSI, PIERGIORGIO, SIEGMUND O. H. W., SPADARO D., BENNA C., CIARAVELLA A., GIORDANO S., HABBAL S., KAROVSKA M., LI X., MARTIN R., MICHELS J. G., MODIGLIANI A., NALETTO, GIAMPIERO, O'NEAL R. H., PERNECHELE C., POLETTO G., SMITH P. L., SULEIMAN R. M.   +30 more
openaire   +2 more sources

A New Phase for Space Weather

Space Weather, Volume 24, Issue 4, April 2026.
Abstract As we move into the declining phase of solar cycle 25, the sunspot number is going down but space weather impacts are not disappearing. Solar energetic particle events, large x‐ray flares, and geomagnetic storms are still happening and the declining phase will bring a different balance of hazards.
Steven K. Morley
wiley   +1 more source

Impact of Solar Irradiance on Storm‐Time Thermospheric Mass Density Response

Geophysical Research Letters, Volume 53, Issue 6, 28 March 2026.
Abstract As a key parameter in the externally forced ionosphere–thermosphere (IT) system, mass density response to storms is affected by the prevailing solar irradiance. To better understand this relationship, we examine mass density responses to the same storm but with different background solar irradiance levels.
Simin Zhang, Liying Qian, Nicholas Pedatella, Eric Sutton, Noah Peterson, Thomas Berger   +5 more
wiley   +1 more source

Evolution of Open Magnetic Flux During Substorms: The Effects of Dipole Tilt Angle

Geophysical Research Letters, Volume 53, Issue 6, 28 March 2026.
Abstract There is a long‐standing debate on the causes of the semiannual variation of geomagnetic activity. One of the prevailing hypotheses is that the Earth's dipole tilt angle Ψ ${\Psi }$ modulates the dayside reconnection rate, causing the so‐called equinoctial effect. Here we perform the first large‐scale statistical study to test this hypothesis.
A. Nair, L. Holappa, H. Vanhamäki, S. E. Milan   +3 more
wiley   +1 more source

Fully Kinetic Simulations of Ion‐Acoustic Waves in Asymmetric Reconnection With Cold Ions

Geophysical Research Letters, Volume 53, Issue 5, 16 March 2026.
Abstract In collisionless plasma, ion‐acoustic wave (IAW) is an important candidate for enhancing resistivity and viscosity, yet their presence and role in magnetic reconnection remain poorly understood. Here, we employ 2.5‐D particle‐in‐cell simulations to investigate IAWs in asymmetric magnetopause reconnection involving a cold ion population ...
Liangjin Song, Meng Zhou, Liang Wang, Zhihong Zhong, Xinmin Li, Chuanfei Dong, Chuanpeng Hou, Rongxin Tang, Yongyuan Yi, Xiaohua Deng   +9 more
wiley   +1 more source

High-speed streams from coronal holes and the accelerating mechanism of the solar-wind

, 1982
In this paper, the general Mach number equation is derived, and the influence of typical energy forms in the solar wind is analysed in detail. It shows that the accelerating process of the solar wind is influenced critically by the form of heating in the
HU, WR (reprint author), ACAD SINICA,INST MECH,PEKING,PEOPLES R CHINA., 胡文瑞   +1 more
core   +1 more source

Periodic Density Structures Observed in Ulysses Data: First Results

Journal of Geophysical Research: Space Physics, Volume 131, Issue 3, March 2026.
Abstract Periodic density structures (PDSs) are advecting quasi‐periodic (periodicities between several minutes and several hours) density enhancements observed in the solar wind and corona. There is strong evidence that PDSs are formed at the Sun.
Brent M. Randol, Nicholeen Viall, Larry Kepko, Simone Di Matteo   +3 more
wiley   +1 more source

On the Freeze‐In Distance of Solar Wind Fluid Entropy Variability in the Corona

Journal of Geophysical Research: Space Physics, Volume 131, Issue 3, March 2026.
Abstract The strong correlation between solar wind entropy and the frozen‐in ion charge state ratio O7+/O6+ ${\mathrm{O}}^{7+}/{\mathrm{O}}^{6+}$ indicates that entropy variability on timescales of hours or longer is preserved from its solar source. This prompts the question: where in the solar atmosphere does this entropy variability come from, and at
Aidan J. Nakhleh, Nicholeen M. Viall, Susan T. Lepri, Jim M. Raines   +3 more
wiley   +1 more source

Energy Conversion Pathways Inside Kelvin‐Helmholtz Vortices

Journal of Geophysical Research: Space Physics, Volume 131, Issue 3, March 2026.
Abstract Energy transfer, cross‐scale coupling, and dissipation in astrophysical plasmas remain fundamental unresolved problems. The velocity‐shear–driven Kelvin–Helmholtz instability (KHI), ubiquitous in plasmas, is a key multiscale mechanism enabling plasma mixing, particle energization and the solar wind–magnetosphere coupling, making it a critical ...
A. Settino, Z. Vörös, L. Sorriso‐Valvo, C. Simon‐Wedlund, O. W. Roberts, R. Nakamura   +5 more
wiley   +1 more source

On the topology of global coronal magnetic fields

, 2014
This thesis considers the magnetic topology of the global solar corona. To understand the magnetic topology we use the magnetic skeleton which provides us with a robust description of the magnetic field.
Edwards, Sarah J.
core