scholarly journals The effect of changing solar wind conditions on the inner magnetosphere and ring current: A model data comparison

2015 ◽  
Vol 120 (8) ◽  
pp. 6528-6540 ◽  
Author(s):  
S. Patra ◽  
E. Spencer
Keyword(s):  
Solar Wind ◽  
Ring Current ◽  
Model Data ◽  
Inner Magnetosphere ◽  
Data Comparison

Solar Wind Deflection in the Foreshock: Model‐Data Comparison

2020 ◽  
Vol 125 (2) ◽  
Author(s):  
O. Gutynska ◽  
N. Omidi ◽  
D. G. Sibeck ◽  
Z. Nemecek ◽  
J. Safrankova ◽  
...  
Keyword(s):  
Solar Wind ◽  
Model Data ◽  
Data Comparison

scholarly journals Dynamics of the terrestrial radiation belts: a review of recent results during the VarSITI (Variability of the Sun and Its Terrestrial Impact) era, 2014–2018

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Shrikanth Kanekal ◽  
Yoshizumi Miyoshi
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ring Current ◽  
Plasma Waves ◽  
Radiation Belts ◽  
The Sun ◽  
Plasma Convection ◽  
Outer Radiation Belt ◽  
Inner Magnetosphere

AbstractThe Earth’s magnetosphere is region that is carved out by the solar wind as it flows past and interacts with the terrestrial magnetic field. The inner magnetosphere is the region that contains the plasmasphere, ring current, and the radiation belts all co-located within about 6.6 Re, nominally taken to be bounding this region. This region is highly dynamic and is home to a variety of plasma waves and particle populations ranging in energy from a few eV to relativistic and ultra-relativistic electrons and ions. The interplanetary magnetic field (IMF) embedded in the solar wind via the process of magnetic reconnection at the sub-solar point sets up plasma convection and creates the magnetotail. Magnetic reconnection also occurs in the tail and is responsible for explosive phenomena known as substorms. Substorms inject low-energy particles into the inner magnetosphere and help generate and sustain plasma waves. Transients in the solar wind such as coronal mass ejections (CMEs), co-rotating interaction regions (CIRs), and interplanetary shocks compress the magnetosphere resulting in geomagnetic storms, energization, and loss of energetic electrons in the outer radiation belt nad enhance the ring current, thereby driving the geomagnetic dynamics. The Specification and Prediction of the Coupled Inner-Magnetospheric Environment (SPeCIMEN) is one of the four elements of VarSITI (Variability of the Sun and Its Terrestrial Impact) program which seeks to quantitatively predict and specify the inner magnetospheric environment based on Sun/solar wind driving inputs. During the past 4 years, the SPeCIMEN project has brought together scientists and researchers from across the world and facilitated their efforts to achieve the project goal. This review provides an overview of some of the significant scientific advances in understanding the dynamical processes and their interconnectedness during the VarSITI era. Major space missions, with instrument suites providing in situ measurements, ground-based programs, progress in theory, and modeling are briefly discussed. Open outstanding questions and future directions of inner magnetospheric research are explored.

Understanding the controlling factors of Ultra-Low Frequency waves and their penetration during geomagnetic storms

2020 ◽  
Author(s):  
Jonathan Rae ◽  
Kyle Murphy ◽  
Clare Watt ◽  
Jasmine Sandhu ◽  
Samuel Wharton ◽  
...  
Keyword(s):  
Solar Wind ◽  
Radiation Belt ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Particle Interaction ◽  
Low Frequency ◽  
Controlling Factors ◽  
Wave Power ◽  
Inner Magnetosphere ◽  
Ulf Wave

<p>Wave-particle interactions play a key role in radiation belt dynamics. Traditionally, Ultra-Low Frequency (ULF) wave-particle interaction is parameterised statistically by a small number of controlling factors for given solar wind driving conditions or geomagnetic activity levels. Here, we investigate solar wind driving of ultra-low frequency (ULF) wave power and the role of the magnetosphere in screening that power from penetrating deep into the inner magnetosphere. We demonstrate that, during enhanced ring current intensity, the Alfvén continuum plummets, allowing lower frequency waves to penetrate deeper into the magnetosphere than during quiet periods. With this penetration, ULF wave power is able to accumulate closer to the Earth than characterised by statistical models. During periods of enhanced solar wind driving such as coronal mass ejection driven storms, where ring current intensities maximise, the observed penetration provides a simple physics-based reason for why storm-time ULF wave power is different compared to non-storm time waves. We demonstrate statistically that the ring current plays a pivotal role in allowing ULF wave energy to access the inner magnetosphere and show a new parameterisation of ULF wave power for radiation belt research purposes that is specifically tuned for geomagnetic storms.</p>

scholarly journals Prediction of SYM-H index during large storms by NARX neural network from IMF and solar wind data

2010 ◽  
Vol 28 (2) ◽  
pp. 381-393 ◽  
Author(s):  
L. Cai ◽  
S. Y. Ma ◽  
Y. L. Zhou
Keyword(s):  
Neural Network ◽  
Solar Wind ◽  
Correlation Coefficient ◽  
Characteristic Time ◽  
Ring Current ◽  
Wind Data ◽  
Distinct Advantage ◽  
Elman Network ◽  
H Index ◽  
Narx Neural Network

Abstract. Similar to the Dst index, the SYM-H index may also serve as an indicator of magnetic storm intensity, but having distinct advantage of higher time-resolution. In this study the NARX neural network has been used for the first time to predict SYM-H index from solar wind (SW) and IMF parameters. In total 73 time intervals of great storm events with IMF/SW data available from ACE satellite during 1998 to 2006 are used to establish the ANN model. Out of them, 67 are used to train the network and the other 6 samples for test. Additionally, the NARX prediction model is also validated using IMF/SW data from WIND satellite for 7 great storms during 1995–1997 and 2005, as well as for the July 2000 Bastille day storm and November 2001 superstorm using Geotail and OMNI data at 1 AU, respectively. Five interplanetary parameters of IMF Bz, By and total B components along with proton density and velocity of solar wind are used as the original external inputs of the neural network to predict the SYM-H index about one hour ahead. For the 6 test storms registered by ACE including two super-storms of min. SYM-H<−200 nT, the correlation coefficient between observed and NARX network predicted SYM-H is 0.95 as a whole, even as high as 0.95 and 0.98 with average relative variance of 13.2% and 7.4%, respectively, for the two super-storms. The prediction for the 7 storms with WIND data is also satisfactory, showing averaged correlation coefficient about 0.91 and RMSE of 14.2 nT. The newly developed NARX model shows much better capability than Elman network for SYM-H prediction, which can partly be attributed to a key feedback to the input layer from the output neuron with a suitable length (about 120 min). This feedback means that nearly real information of the ring current status is effectively directed to take part in the prediction of SYM-H index by ANN. The proper history length of the output-feedback may mainly reflect on average the characteristic time of ring current decay which involves various decay mechanisms with ion lifetimes from tens of minutes to tens of hours. The Elman network makes feedback from hidden layer to input only one step, which is of 5 min for SYM-H index in this work and thus insufficient to catch the characteristic time length.

scholarly journals The Last Glacial Maximum and Heinrich Event 1 in terms of climate and vegetation around the Alboran Sea: a preliminary model-data comparison

2005 ◽  
Vol 337 (10-11) ◽  
pp. 983-992 ◽  
Author(s):  
Masa Kageyama ◽  
Nathalie Combourieu Nebout ◽  
Pierre Sepulchre ◽  
Odile Peyron ◽  
Gerhard Krinner ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Model Data ◽  
Last Glacial ◽  
Data Comparison ◽  
Heinrich Event ◽  
Preliminary Model ◽  
The Last Glacial Maximum ◽  
Heinrich Event 1 ◽  
The Last Glacial

Weichselian Late Pleniglacial surface winds over northwest and central Europe: a model–data comparison

2007 ◽  
Vol 22 (3) ◽  
pp. 281-293 ◽  
Author(s):  
H. Renssen ◽  
C. Kasse ◽  
J. Vandenberghe ◽  
S. J. Lorenz
Keyword(s):  
Central Europe ◽  
Surface Winds ◽  
Model Data ◽  
Data Comparison

scholarly journals Another way of deriving the ring current decay time during disturbed periods

1995 ◽  
Vol 38 (2) ◽  
Author(s):  
M. M. Zossi de Artigas ◽  
J. R. Manzano
Keyword(s):  
Ring Current ◽  
Coupling Parameter ◽  
Life Time ◽  
Recovery Phase ◽  
Main Phase ◽  
Physical Analysis ◽  
Inner Magnetosphere ◽  
Current Decay ◽  
The Many ◽  
Energy Dissipated

Coupling parameter, E, and the total energy dissipated by the magnetosphere, UT, are determined for six disturbed periods, following three known criteria for UT computation. It is observed that UT exceeds E for Dst < -90 nT, for alI models. Differences between models reside on the estimated valnes for the particles' life time il1 the equatorial ring current. The values of TR, used in the models, are small during the main phase of the di."turbance, in disagreement with the charge exchange life time of the majority species, H+ and O'-. Based on this conclusion, a different criterion to calculate TR is proposed, differentiating the different stages of the perturbation. TR is calculated, for the main phase of the storm, from the rate of energy deposition estimation, Q, in the ring current. For Dst recovery phase, the vallles are obtained from a ring current decay law computation. The UTvu calculated, physically more coherent with the processes occurring during the event, is now smaller than expected. In this sense, it is understood that the power generated by the solar wind-magnetosphere dy- namo, should also be distributed in the inner magnetosphere, auroral zones and equatorial ring current, as in the outer magnetosphere, plasmoids in the tail shot in antisolar direction. A further adjustment of E, with the Chapman-Ferraro distance, 10' variable, has been made. Although the reslllts, improve the estimation of E, they are sti!l smaller than UT, except UTNU, for some disturbed periods. This result indicates the uncertainty in the computation of the input energy, by using the many expressions proposed in the literature, which are always presented as laws proportional to a given group of parameters, with an unknown factor of proportionality, which deserves more detailed physical analysis.

scholarly journals Global estimates of plasmaspheric losses during moderate disturbance intervals

2010 ◽  
Vol 28 (1) ◽  
pp. 27-36 ◽  
Author(s):  
M. Spasojevic ◽  
B. R. Sandel
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Boundary Layers ◽  
Total Mass ◽  
Density Ratio ◽  
Individual Case ◽  
Number Density ◽  
Inner Magnetosphere ◽  
Moderate Disturbance ◽  
Global Estimates

Abstract. For a set of five moderate disturbance events, we calculate the total number of He+ ions removed the plasmasphere using calibrated global EUV images. In each of the events, between ~0.6 and 2.2×1030 He+ ions are removed from a region of the inner magnetosphere from L=1.5 to 5.5. This loss constitutes between 20% and 42% of the initial He+ distribution. The lost percentage is correlated with the number of hours of strongly positive solar wind electric field (Ey>2.5 mV/m). Also, the total amount of material removed from the plasmasphere is estimated by using several values of the He+ to H+ number density ratio. The total mass lost is found to be in the range of 20 to 80 metric tons although for each individual case the estimate can vary by over 50% depending on assumed density ratio. We also attempt to distinguish between losses to the ionosphere and losses to the dayside boundary layers by estimating losses interior and exterior to the newly formed plasmapause boundary. For the events studied, losses inside the new plasmapause constitute between 24% to 54% of the total number of He+ ions lost.

scholarly journals Magnetospheric Response to Solar Wind Forcing: ULF Wave – Particle Interaction Perspective

2021 ◽  
Author(s):  
Qiugang Zong
Keyword(s):  
Solar Wind ◽  
Radiation Belt ◽  
Ring Current ◽  
Dynamic Pressure ◽  
Plasma Heating ◽  
Interplanetary Shock ◽  
Wind Forcing ◽  
Ulf Waves ◽  
Radiation Belt Electrons ◽  
The Impact

Abstract. Solar wind forcing, e.g. interplanetary shock and/or solar wind dynamic pressure pulses impact on the Earth’s magnetosphere manifests many fundamental important space physics phenomena including producing electromagnetic waves, plasma heating and energetic particle acceleration. This paper summarizes our present understanding of the magnetospheric response to solar wind forcing in the aspects of radiation belt electrons, ring current ions and plasmaspheric plasma physics based on in situ spacecraft measurements, ground-based magnetometer data, MHD and kinetic simulations. Magnetosphere response to solar wind forcing, is not just a “one-kick” scenario. It is found that after the impact of solar wind forcing on the Earth’s magnetosphere, plasma heating and energetic particle acceleration started nearly immediately and could last for a few hours. Even a small dynamic pressure change of interplanetary shock or solar wind pressure pulse can play a non-negligible role in magnetospheric physics. The impact leads to generate series kind of waves including poloidal mode ultra-low frequency (ULF) waves. The fast acceleration of energetic electrons in the radiation belt and energetic ions in the ring current region response to the impact usually contains two contributing steps: (1) the initial adiabatic acceleration due to the magnetospheric compression; (2) followed by the wave-particle resonant acceleration dominated by global or localized poloidal ULF waves excited at various L-shells. Generalized theory of drift and drift-bounce resonance with growth or decay localized ULF waves has been developed to explain in situ spacecraft observations. The wave related observational features like distorted energy spectrum, boomerang and fishbone pitch angle distributions of radiation belt electrons, ring current ions and plasmaspheric plasma can be explained in the frame work of this generalized theory. It is worthy to point out here that poloidal ULF waves are much more efficient to accelerate and modulate electrons (fundamental mode) in the radiation belt and charged ions (second harmonic) in the ring current region. The results presented in this paper can be widely used in solar wind interacting with other planets such as Mercury, Jupiter, Saturn, Uranus and Neptune, and other astrophysical objects with magnetic fields.

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