Results 61 to 70 of about 285 (167)

Decent Estimate of CME Arrival Time From a Data‐Assimilated Ensemble in the Alfvén Wave Solar Atmosphere Model (DECADE‐AWSoM)

Space Weather, Volume 23, Issue 1, January 2025.
Abstract Forecasting the arrival time of Earth‐directed coronal mass ejections (CMEs) via physics‐based simulations is an essential but challenging task in space weather research due to the complexity of the underlying physics and limited remote and in situ observations of these events. Data assimilation techniques can assist in constraining free model
Hongfan Chen, Nishtha Sachdeva, Zhenguang Huang, Bart van der Holst, Ward Manchester IV, Aniket Jivani, Shasha Zou, Yang Chen, Xun Huan, Gabor Toth   +9 more
wiley   +1 more source

Structure of the Solar Atmosphere: A Radio Perspective

Frontiers in Astronomy and Space Sciences, 2020
Solar radio emission has been providing information about the Sun for over half a century. In order to fully exploit this information, one needs to have a broader view of the solar atmosphere, which cannot be provided by radio observations alone.
Costas E. Alissandrakis
doaj   +1 more source

Solar chromospheric emission and magnetic structures from plages to intranetwork: Contribution of the very quiet Sun [PDF]

Astronomy & Astrophysics, 2018
Context. We need to establish a correspondence between the magnetic structures generated by models and usual stellar activity indexes to simulate radial velocity time series for stars less active than the Sun. This is necessary to compare the outputs of such models with observed radial velocity jitters and is critical to better understand the impact of
openaire   +4 more sources

MEMPSEP‐III. A Machine Learning‐Oriented Multivariate Data Set for Forecasting the Occurrence and Properties of Solar Energetic Particle Events Using a Multivariate Ensemble Approach

Space Weather, Volume 22, Issue 9, September 2024.
Abstract We introduce a new multivariate data set that utilizes multiple spacecraft collecting in‐situ and remote sensing heliospheric measurements shown to be linked to physical processes responsible for generating solar energetic particles (SEPs). Using the Geostationary Operational Environmental Satellites (GOES) flare event list from Solar Cycle ...
Kimberly Moreland, Maher A. Dayeh, Hazel M. Bain, Subhamoy Chatterjee, Andrés Muñoz‐Jaramillo, Samuel T. Hart   +5 more
wiley   +1 more source

Full Stokes-vector Inversion of the Solar Mg ii h and k Lines

The Astrophysical Journal
The polarization of the Mg ii h and k resonance lines is the result of the joint action of scattering processes and the magnetic field–induced Hanle, Zeeman, and magneto-optical effects, thus holding significant potential for the diagnostic of the ...
Hao Li, Tanausú del Pino Alemán, Javier Trujillo Bueno   +2 more
doaj   +1 more source

Dynamics of the Quiet Solar Chromosphere

, 1999
The solar chromosphere has never been static although it was often modeled so.Even the quiet-sun internetwork chromosphere has become thoroughly dynamic with the acoustic shock interpretation of the Ca II K 2V grains. We concentrate on the latter in this brief review.
Rutten, R.J., Lites, Bruce W., Berger, T.E., Shine, R.A.   +3 more
openaire   +1 more source

Lyman-alpha rocket spectra and models of the quiet and active solar chromosphere based on partial redistribution diagnostics

The Astrophysical Journal, 1979
Absolute intensity Lyman-alpha profiles with a spatial resolution of 0.8 min and a spectral resolution of 50 mA were obtained for network and cell regions in the quiet sun, umbral and penumbral areas of a sunspot, two plages, and a quiescent prominence of the limb.
G. S. Basri, J. L. Linsky, J.-D. F. Bartoe, G. Brueckner, M. E. van Hoosier   +4 more
openaire   +1 more source

Transition of the Sun to a Regime of High Activity: Implications for the Earth Climate and Role of Atmospheric Chemistry

Journal of Geophysical Research: Atmospheres, Volume 129, Issue 15, 16 August 2024.
Abstract It was recently suggested that the Sun could switch to a high‐activity regime which would lead to a rise of ultraviolet radiation with an amplitude of about four times larger than the amplitude of an average solar activity cycle and a simultaneous drop in total solar irradiance.
Anna V. Shapiro, Tatiana A. Egorova, Alexander I. Shapiro, Pavle Arsenovic, Eugene V. Rozanov, Laurent Gizon   +5 more
wiley   +1 more source

Investigation of Phase Shift and Travel Time of Acoustic Waves in the Lower Solar Atmosphere Using Multiheight Velocities

The Astrophysical Journal
We report and discuss the phase shift and phase travel time of low-frequency ( ν < 5.0 mHz) acoustic waves estimated within the photosphere and photosphere–chromosphere interface regions, utilizing multiheight velocities in the quiet Sun.
Hirdesh Kumar, Brajesh Kumar, Shibu K. Mathew, A. Raja Bayanna, S. P. Rajaguru   +4 more
doaj   +1 more source

The vertical propagation of waves in the solar atmosphere. II Phase delays in the quiet chromosphere and cell-network distinctions

The Astrophysical Journal, 1982
The differences in the phase of the velocity oscillations between a pair of chromospheric Ca II lines was measured using the Vacuum Tower Telescope at the Sacramento Peak Observatory. The observed phase differences indicate that the acoustic modes are trapped or envanescent, rather than propagating, in the chromosphere.
B. W. Lites, E. G. Chipman, O. R. White
openaire   +1 more source