scholarly journals Solar wind density control of energy transfer to the magnetosphere

2004 ◽  
Vol 31 (8) ◽  
Author(s):  
R. E. Lopez
Keyword(s):  
Solar Wind ◽  
Energy Transfer ◽  
Solar Wind Density ◽  
Density Control

MHD simulations of magnetospheric response to a strong solar wind density pulse

2021 ◽  
Author(s):  
Andrey Samsonov ◽  
Jennifer A. Carter ◽  
Graziella Branduardi-Raymont ◽  
Steven Sembay
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Solar Wind Density ◽  
Ionospheric Currents ◽  
X Ray ◽  
Interplanetary Coronal Mass Ejection ◽  
Explorer Mission ◽  
The One ◽  
Mass Ejection ◽  
Present Simulation

<p>On 16-17 June 2012, an interplanetary coronal mass ejection with an extremely high solar wind density (~100 cm<sup>-3</sup>) and mostly strong northward (or eastward) interplanetary magnetic field (IMF) interacted with the Earth’s magnetosphere. We have simulated this event using global MHD models. We study the magnetospheric response to two solar wind discontinuities. The first is characterized by a fast drop of the solar wind dynamic pressure resulting in rapid magnetospheric expansion. The second is a northward IMF turning which causes reconfiguration of the magnetospheric-ionospheric currents. We discuss variations of the magnetopause position and locations of the magnetopause reconnection in response to the solar wind variations. In the second part of our presentation, we present simulation results for the forthcoming SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) mission. SMILE is scheduled for launch in 2024. We produce two-dimensional images that derive from the MHD results of the expected X-ray emission as observed by the SMILE Soft X-ray Imager (SXI). We discuss how SMILE observations may help to study events like the one presented in this work.</p>

Deriving CME volume and density from remote sensing data

2021 ◽  
Author(s):  
Manuela Temmer ◽  
Lukas Holzknecht ◽  
Mateja Dumbovic ◽  
Bojan Vrsnak ◽  
Nishtha Sachdeva ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Remote Sensing Data ◽  
Propagation Speed ◽  
Solar Wind Density ◽  
Sheath Region ◽  
Pile Up ◽  
Mass Ejection ◽  
Interplanetary Propagation

<p>Using combined STEREO-SOHO white-light data, we present a method to determine the volume and density of a coronal mass ejection (CME) by applying the graduated cylindrical shell model (GCS) and deprojected mass derivation. Under the assumption that the CME  mass is roughly equally distributed within a specific volume, we expand the CME self-similarly and calculate the CME density for distances close to the Sun (15–30 Rs) and at 1 AU. The procedure is applied on a sample of 29 well-observed CMEs and compared to their interplanetary counterparts (ICMEs). Specific trends are derived comparing calculated and in-situ measured proton densities at 1 AU, though large uncertainties are revealed due to the unknown mass and geometry evolution: i) a moderate correlation for the magnetic structure having a mass that stays rather constant and ii) a weak correlation for the sheath density by assuming the sheath region is an extra mass - as expected for a mass pile-up process - that is in its amount comparable to the initial CME deprojected mass. High correlations are derived between in-situ measured sheath density and the solar wind density and solar wind speed as measured 24 hours ahead of the arrival of the disturbance. This gives additional confirmation that the sheath-plasma indeed stems from piled-up solar wind material. While the CME interplanetary propagation speed is not related to the sheath density, the size of the CME may play some role in how much material is piled up.</p>

A neural network-based mid-term prognosis of geomagnetic storms that uses pre-storm effects related to current sheets and magnetic islands

2021 ◽  
Author(s):  
Mikhail Fridman
Keyword(s):  
Solar Wind ◽  
Solar Minimum ◽  
High Speed ◽  
Geomagnetic Storms ◽  
Magnetic Islands ◽  
Solar Wind Density ◽  
Short Term ◽  
Storm Effects ◽  
Term Forecast ◽  
Advance Time

<p>Mid-term prognoses of geomagnetic storms require an improvement since theу are known to have rather low accuracy which does not exceed 40% in solar minimum. We claim that the problem lies in the approach. Current mid-term forecasts are typically built using the same paradigm as short-term ones and suggest an analysis of the solar wind conditions typical for geomagnetic storms. According to this approach, there is a 20-60 minute delay between the arrival of a geoeffective flow/stream to L1 and the arrival of the signal from the spacecraft to Earth, which gives a necessary advance time for a short-term prognosis. For the mid-term forecast with an advance time from 3 hours to 3 days, this is not enough. Therefore, we have suggested finding precursors of geomagnetic storms observed in the solar wind. Such precursors are variations in the solar wind density and the interplanetary magnetic field in the ULF range associated with crossings of magnetic cavities in front of the arriving geoeffective high-speed streams and flows (Khabarova et al., 2015, 2016, 2018; Adhikari et al., 2019). Despite some preliminary studies have shown that this might be a perspective way to create a mid-term prognosis (Khabarova 2007; Khabarova & Yermolaev, 2007), the problem of automatization of the prognosis remained unsolved.</p>

Turbulent energy transfer in bidimensional numerical models of plasma

2021 ◽  
Author(s):  
Rocio Manobanda ◽  
Christian Vasconez ◽  
Denise Perrone ◽  
Raffaele Marino ◽  
Dimitri Laveder ◽  
...  
Keyword(s):  
Solar Wind ◽  
Energy Transfer ◽  
Numerical Models ◽  
Collisionless Plasma ◽  
Space Plasma ◽  
Turbulent Energy ◽  
Turbulent Medium ◽  
Scaling Properties ◽  
Magnetic Diffusivity ◽  
Out Of Plane

<p>Structured, highly variable and virtually collision-free. Space plasma is an unique laboratory for studying the transfer of energy in a highly turbulent environment. This turbulent medium plays an important role in various aspects of the Solar--Wind generation, particles acceleration and heating, and even in the propagation of cosmic rays. Moreover, the Solar Wind continuous expansion develops a strong turbulent character, which evolves towards a state that resembles the well-known hydrodynamic turbulence (Bruno and Carbone). This turbulence is then dissipated from magnetohydrodynamic (MHD) through kinetic scales by different -not yet well understood- mechanisms. In the MHD approach, Kolmogorov-like behaviour is supported by power-law spectra and intermittency measured in observations of magnetic and velocity fluctuations. In this regime, the intermittent cross-scale energy transfer has been extensively described by the Politano--Pouquet (global) law, which is based on conservation laws of the MHD invariants, and was recently expanded to take into account the physics at the bottom of the inertial (or Hall) range, e.g. (Ferrand et al., 2019). Following the 'Turbulence Dissipation Challenge', we study the properties of the turbulent energy transfer using three different bi-dimensional numerical models of space plasma. The models, Hall-MHD (HMHD), Landau Fluid (LF) and Hybrid Vlasov-Maxwell (HVM), were ran in collisionless-plasma conditions, with an out-of-plane ambient magnetic field, and with magnetic diffusivity carefully calibrated in the fluid models. As each model has its own range of validity, it allows us to explore a long-enough range of scales at a period of maximal turbulence activity. Here, we estimate the local and global scaling properties of different energy channels using a, recently introduced, proxy of the local turbulent energy transfer (LET) rate (Sorriso-Valvo et al., 2018). This study provides information on the structure of the energy fluxes that transfers (and dissipates) most of the energy at small scales throughout the turbulent cascade. </p>

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