scholarly journals A global MHD simulation of an event with a quasi-steady northward IMF component

2007 ◽  
Vol 25 (6) ◽  
pp. 1345-1358 ◽  
Author(s):  
V. G. Merkin ◽  
J. G. Lyon ◽  
B. J. Anderson ◽  
H. Korth ◽  
C. C. Goodrich ◽  
...  
Keyword(s):  
Energy Flux ◽  
Particle Energy ◽  
Ionospheric Currents ◽  
Poynting Flux ◽  
Mhd Simulations ◽  
Magnetic Perturbations ◽  
Magnetometer Data ◽  
Mhd Modeling ◽  
Field Aligned Current ◽  
Global Mhd Simulation

Abstract. We show results of the Lyon-Fedder-Mobarry (LFM) global MHD simulations of an event previously examined using Iridium spacecraft observations as well as DMSP and IMAGE FUV data. The event is chosen for the steady northward IMF sustained over a three-hour period during 16 July 2000. The Iridium observations showed very weak or absent Region 2 currents in the ionosphere, which makes the event favorable for global MHD modeling. Here we are interested in examining the model's performace during weak magnetospheric forcing, in particular, its ability to reproduce gross signatures of the ionospheric currents and convection pattern and energy deposition in the ionosphere both due to the Poynting flux and particle precipitation. We compare the ionospheric field-aligned current and electric potential patterns with those recovered from Iridium and DMSP observations, respectively. In addition, DMSP magnetometer data are used for comparisons of ionospheric magnetic perturbations. The electromagnetic energy flux is compared with Iridium-inferred values, while IMAGE FUV observations are utilized to verify the simulated particle energy flux.

scholarly journals High-latitude poynting flux from combined Iridium and SuperDARN data

2004 ◽  
Vol 22 (8) ◽  
pp. 2861-2875 ◽  
Author(s):  
C. L. Waters ◽  
B. J. Anderson ◽  
R. A. Greenwald ◽  
R. J. Barnes ◽  
J. M. Ruohoniemi
Keyword(s):  
Electric Fields ◽  
Energy Flux ◽  
High Latitude ◽  
Electromagnetic Energy ◽  
Total Power ◽  
Data Sets ◽  
Poynting Flux ◽  
Magnetic Perturbations ◽  
Magnetometer Data ◽  
A New Technique

Abstract. Field-aligned currents convey stress between the magnetosphere and ionosphere, and the associated low altitude magnetic and electric fields reflect the flow of electromagnetic energy to the polar ionosphere. We introduce a new technique to measure the global distribution of high latitude Poynting flux, S||, by combining electric field estimates from the Super Dual Auroral Radar Network (SuperDARN) with magnetic perturbations derived using magnetometer data from the Iridium satellite constellation. Spherical harmonic methods are used to merge the data sets and calculate S|| for any magnetic local time (MLT) from the pole to 60° magnetic latitude (MLAT). The effective spatial resolutions are 2° MLAT, 2h MLT, and the time resolution is about one hour due to the telemetry rate of the Iridium magnetometer data. The technique allows for the assessment of high-latitude net S|| and its spatial distribution on one hour time scales with two key advantages: (1) it yields the net S|| including the contribution of neutral winds; and (2) the results are obtained without recourse to estimates of ionosphere conductivity. We present two examples, 23 November 1999, 14:00-15:00 UT, and 11 March 2000, 16:00-17:00 UT, to test the accuracy of the technique and to illustrate the distributions of S|| that it gives. Comparisons with in-situ S|| estimates from DMSP satellites show agreement to a few mW/m2 and in the locations of S|| enhancements to within the technique's resolution. The total electromagnetic energy flux was 50GW for these events. At auroral latitudes, S|| tends to maximize in the morning and afternoon in regions less than 5° in MLAT by two hours in MLT having S||=10 to 20mW/m2 and total power up to 10GW. The power poleward of the Region 1 currents is about one-third of the total power, indicating significant energy flux over the polar cap.

scholarly journals RELATIVISTIC MHD SIMULATIONS OF COLLISION-INDUCED MAGNETIC DISSIPATION IN POYNTING-FLUX-DOMINATED JETS/OUTFLOWS

2015 ◽  
Vol 805 (2) ◽  
pp. 163 ◽  
Author(s):  
Wei Deng (邓巍) ◽  
Hui Li (李晖) ◽  
Bing Zhang (张冰) ◽  
Shengtai Li (李胜台)
Keyword(s):  
Poynting Flux ◽  
Mhd Simulations

scholarly journals RELATIVISTIC MHD SIMULATIONS OF POYNTING FLUX-DRIVEN JETS

2014 ◽  
Vol 781 (1) ◽  
pp. 48 ◽  
Author(s):  
Xiaoyue Guan ◽  
Hui Li ◽  
Shengtai Li
Keyword(s):  
Poynting Flux ◽  
Mhd Simulations

scholarly journals High-latitude electromagnetic and particle energy flux during an event with sustained strongly northward IMF

2005 ◽  
Vol 23 (4) ◽  
pp. 1295-1310 ◽  
Author(s):  
H. Korth ◽  
B. J. Anderson ◽  
H. U. Frey ◽  
C. L. Waters
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Energy Flux ◽  
High Latitude ◽  
Energy Transport ◽  
Small Region ◽  
Radial Component ◽  
Particle Energy ◽  
Electromagnetic Energy ◽  
Viscous Interaction

Abstract. We present a case study of a prolonged interval of strongly northward orientation of the interplanetary magnetic field on 16 July 2000, 16:00-19:00 UT to characterize the energy exchange between the magnetosphere and ionosphere for conditions associated with minimum solar wind-magnetosphere coupling. With reconnection occurring tailward of the cusp under northward IMF conditions, the reconnection dynamo should be separated from the viscous dynamo, presumably driven by the Kelvin-Helmholtz (KH) instability. Thus, these conditions are also ideal for evaluating the contribution of a viscous interaction to the coupling process. We derive the two-dimensional distribution of the Poynting vector radial component in the northern sunlit polar ionosphere from magnetic field observations by the constellation of Iridium satellites together with drift meter and magnetometer observations from the Defense Meteorological Satellite Program (DMSP) F13 and F15 satellites. The electromagnetic energy flux is then compared with the particle energy flux obtained from auroral images taken by the far-ultraviolet (FUV) instrument on the Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft. The electromagnetic energy input to the ionosphere of 51 GW calculated from the Iridium/DMSP observations is eight times larger than the 6 GW due to particle precipitation all poleward of 78° MLAT. This result indicates that the energy transport is significant, particularly as it is concentrated in a small region near the magnetic pole, even under conditions traditionally considered to be quiet and is dominated by the electromagnetic flux. We estimate the contributions of the high and mid-latitude dynamos to both the Birkeland currents and electric potentials finding that high-latitude reconnection accounts for 0.8 MA and 45kV while we attribute <0.2MA and ~5kV to an interaction at lower latitudes having the sense of a viscous interaction. Given that these conditions are ideal for the occurrence of the KH instability at the magnetopause and hence the viscous interaction, this result suggests that the viscous interaction is a small contributor to coupling solar wind energy to the magnetosphere-ionosphere system.

scholarly journals Comparing ground magnetic field perturbations from global MHD simulations with magnetometer data for the 10 January 1997 magnetic storm event

2002 ◽  
Vol 107 (A8) ◽  
pp. SMP 11-1-SMP 11-10 ◽  
Author(s):  
X. Shao ◽  
P. N. Guzdar ◽  
G. M. Milikh ◽  
K. Papadopoulos ◽  
C. C. Goodrich ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Storm ◽  
Storm Event ◽  
Mhd Simulations ◽  
Magnetometer Data ◽  
Ground Magnetic

scholarly journals On the possibility of using an electromagnetic ionosphere in global MHD simulations

1998 ◽  
Vol 16 (4) ◽  
pp. 397-402 ◽  
Author(s):  
P. Janhunen
Keyword(s):  
Electric Field ◽  
Source Term ◽  
Interaction Space ◽  
Mhd Equations ◽  
Coupling Scheme ◽  
Simulation Studies ◽  
Mhd Simulations ◽  
Field Aligned Current ◽  
Flow Of Information ◽  
Ionospheric Potential

Abstract. Global magnetohydrodynamic (MHD) simulations of the Earth's magnetosphere must be coupled with a dynamical ionospheric module in order to give realistic results. The usual approach is to compute the field-aligned current (FAC) from the magnetospheric MHD variables at the ionospheric boundary. The ionospheric potential is solved from an elliptic equation using the FAC as a source term. The plasma velocity at the boundary is the E × B velocity associated with the ionospheric potential. Contemporary global MHD simulations which include a serious ionospheric model use this method, which we call the electrostatic approach in this paper. We study the possibility of reversing the flow of information through the ionosphere: the magnetosphere gives the electric field to the ionosphere. The field is not necessarily electrostatic, thus we will call this scheme electromagnetic. The electric field determines the horizontal ionospheric current. The divergence of the horizontal current gives the FAC, which is used as a boundary condition for MHD equations. We derive the necessary formulas and discuss the validity of the approximations necessarily involved. It is concluded that the electromagnetic ionosphere-magnetosphere coupling scheme is a serious candidate for future global MHD simulators, although a few problem areas still remain. At minimum, it should be investigated further to discover whether there are any differences in the simulation using the electrostatic or the electromagnetic ionospheric coupling.Key words. Ionosphere · Ionosphere-magnetosphere interaction · Magnetospheric physics · Magnetosphere-ionosphere interaction · Space plasma physics · Numerical simulation studies

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