Search Publications
Milne-Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere
Bommier, Véronique
This paper is first devoted to present our method for modeling unresolved magnetic structures in the Milne-Eddington inversion of spectropolarimetric data. The related definitions and other approaches and different used inversion algorithms are recalled for comparison. In a second part, we apply our method to quiet Sun data outside active regions.…
Some new aspects of the transient ionization layer of comet Siding Spring origin in the Martian upper atmosphere
Venkateswara Rao, N.; Rao, S. V. B.; ManasaMohana, P. +1 more
The close encounter of comet Siding Spring with Mars resulted in the formation of a dense transient ionization layer in the Martian upper atmosphere at altitudes between 80 and 120 km. Instruments on three spacecraft orbiting Mars detected the presence of this layer, as reported in previous publications. In this study, we reanalyzed the ionograms …
MHD-IPS analysis of relationship among solar wind density, temperature, and flow speed
Hayashi, Keiji; Tokumaru, Munetoshi; Fujiki, Ken'ichi
The solar wind properties near the Sun are a decisive factor of properties in the rest of heliosphere. As such, determining realistic plasma density and temperature near the Sun is very important in models for solar wind, specifically magnetohydrodynamics (MHD) models. We had developed a tomographic analysis to reconstruct three-dimensional solar …
The role of ionospheric O+ outflow in the generation of earthward propagating plasmoids
Lyon, J. G.; Zhang, B.; Ouellette, J. E. +2 more
Earthward propagating plasmoids in the Earth's magnetotail have been observed by satellites. Using a multifluid global magnetosphere simulation, earthward propagating plasmoids are reproduced when ionospheric O+ outflow is included in the global simulation. Controlled simulations show that without ionospheric outflow, the plasmoids gene…
Asymmetrical response of dayside ion precipitation to a large rotation of the IMF
Berchem, J.; Richard, R. L.; Escoubet, C. P. +2 more
We have carried out global magnetohydrodynamics (MHD) simulations together with large-scale kinetic simulations to investigate the response of the dayside magnetospheric ion precipitation to a large rotation (135°) of the interplanetary magnetic field (IMF). The study uses simplified global MHD model (no dipole tilt and constant ionospheric conduc…
Coronal electron density distributions estimated from CMEs, DH type II radio bursts, and polarized brightness measurements
Moon, Y. -J.; Lee, Kyoung-Sun; Kim, R. -S. +2 more
We determine coronal electron density distributions (CEDDs) by analyzing decahectometric (DH) type II observations under two assumptions. DH type II bursts are generated by either (1) shocks at the leading edges of coronal mass ejections (CMEs) or (2) CME shock-streamer interactions. Among 399 Wind/WAVES type II bursts (from 1997 to 2012) associat…
Equatorial noise emissions with a quasiperiodic modulation observed by DEMETER at harmonics of the O+ ion gyrofrequency
Němec, František; Santolík, Ondřej; Cornilleau-Wehrlin, Nicole +1 more
The analysis of ionospheric equatorial noise (EN) with a quasiperiodic (QP) modulation observed by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft is presented. These EN emissions, also called whistler mode or fast magnetosonic waves, play an important role in acceleration of radiation belt elec…
A study of cosmic ray flux based on the noise in raw CCD data from solar images
Qin, G.; Shen, Z. -N.
Raw solar images from CCDs are often contaminated with single-pixel noise which is thought to be made by cosmic ray hits. The cosmic ray-affected pixels are usually outstanding when compared with the perimeter zone. In this work, we use a method based on the median filtering algorithm to identify and count the cosmic ray traces from SOHO/EIT solar…
Spatial distribution of Langmuir waves observed upstream of Saturn's bow shock by Cassini
Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S. +3 more
We present the spatial distribution and spectral properties of Langmuir waves observed upstream of Saturn's bow shock by the Cassini spacecraft. The entire 10 kHz wideband data set obtained between June 2004 and December 2014 has been analyzed using an automated procedure. Almost 106 waveform snapshots with intense narrowband emissions …
Statistical study on ultralow-frequency waves in the magnetotail lobe observed by Cluster
Zhang, T. L.; Volwerk, M.; Wang, G. Q.
Based on Cluster data, we investigate 263 waves with periods between 40 and 150 s (Pi2 band events) and 161 waves with periods between 150 and 600 s (Pc5 band events) in the magnetotail lobe. Our findings are as follows: (1) 90% of the mean wave amplitudes within 40-150 s (150-600 s) are below ~0.25 (0.36) nT for the transverse components and ~0.1…