Response of the Magnetosphere and Ionosphere to Solar Wind Dynamic Pressure Pulse
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Transcript of Response of the Magnetosphere and Ionosphere to Solar Wind Dynamic Pressure Pulse
Response of the Magnetosphere and Ionosphere to
Solar Wind Dynamic Pressure Pulse
Response of the Magnetosphere and Ionosphere to
Solar Wind Dynamic Pressure Pulse
KYUNG SUN PARK1, TATSUKI OGINO2, and DAE-YOUNG LEE3
1School of Space Research, Kyung Hee University, Korea2Solar-Terrestrial Environment Laboratory, Nagoya University, Japan 3Dept. Astronomy and Space Science, Chungbuk National University, Korea
2009 UN BSS & IHY Workshop, September 21-25, 2009
IntroductionIntroduction
The interaction of the solar wind with Earth’s magnetosphere produces various phenomena, such as substorms and aurora, in the polar region.
When the IMF turns southward, the energy of the solar wind is efficiently trapped by reconnection in the magnetosphere, and convection and currents within in the magnetosphere increase.
The orientation of the IMF has significant effects on convection pattern and the FAC system in the magnetosphere. [Fairfied and Cahill, 1966; Reiff and Bursh, 1985: Cowley and Lockwood, 1992] . Pure Southward
Pure Northward By T. Ogino
θY
Z
Tilt angle 0°
Tilt angle 30°
Effect of the dipole tilt angleEffect of the dipole tilt angle
When the northern hemisphere is summer, the dayside reconnection occurred slightly below the magnetic equator in the start from 30 degree.
Dayside Reconnection rate :30 tilt ~ 0.84 times 0 tilt
Configuration of the magnetic field lines
Southward IMF (315°) + dipole tilt (30°)
Northward IMF (45°) + dipole tilt (30°)
Configuration of the magnetic field lines
[Park et al. 2006, 2009]
# A quasi-steady state configuration usually resulted after about 3 hours in real time.
X
Z
X
Y
1. Dusk sector (northern hemisphere)2. Move to dawn in the dayside 3. Come back to dusk in the tail4. Tail reconnection successively occurs in the slant and elevated plasma sheet.
Effect of the dipole tilt and IMF conditionEffect of the dipole tilt and IMF condition
Bz
By
Bz
By
Northward IMF (45°) + dipole tilt (30°)Southward IMF (315°) + dipole tilt (30°)
Electric field |E| and Resistivity electric field
0.1 times
E
ηJ
J|| J┴
E ηJ
J||
J┴
EAPN (1.2) EAPS (1.1) ≥ EME(0.2) ≥ ESS (0.1 mV/m) EAPN , EAPS (0.4) ≥ EME, ESS (0.15 mV/m) The parallel component of the current (J||) in the southern hemisphere is larger than northern hemisphere when the dipole tilt is positive. The feature is different result from the southward IMF condition [Park et al., 2006, 2009].
Northward IMF (45°) + dipole tilt (30°)
In a view form the dusk
In a view form the top
In a view form the Sun
Northward IMF (45°) + dipole tilt (30°)Southward IMF (315°) + dipole tilt (30°)
The reason of different J|| in the reconnection region between the southward and northward IMF condition
Orientation of IMF and dipole tilt (30)Orientation of IMF and dipole tilt (30)
Electric field |E| (E = -VB+ J)
• EAPN > EAPS
The electric field in the northern hemisphere is almost 3 times larger than that in the southern hemisphere for 45 .
Polar cap potential saturation process and dayside magnetic reconnection enhancement [Boudouridis et. al., 2004] Polar cap (PC) index enhancement [Lukianova, 2003] Sawtooth oscillations in energetic particle flux and magnetic field at geosynchronous orbit [Lee et. al., 2004] Auroral-region disturbance [Lyons et al., 2005] Substorm triggering
The effect of sudden enhancements of solar wind dynamic pressure on the magnetosphere and ionosphere
Simulation MethodSimulation Method
The number of grid points (nx, ny, nz) = (300, 100, 100) with a grid spacing of 0.3 RE. Solar wind parameters:• IMF |B| = 0 nT, 2 nT and 10 nT • Solar wind density : nsw = 5/cc and 10/cc• Solar wind velocity : Vsw = 300 km/s
Simulation conditionSimulation condition
Condition 1 : constant Bz and variable dynamic pressure
Condition 4 : Bz south to northward
60 min t
5
10
[/cm-3]
Bz = -2 nT and -10 nTdensity
-2
-10
Density = 5 and 10 /cm-3
Bz[nT]
60 min t
Condition 2 : more southward Bz and constant dynamic pressure
Condition 3 : Bz change with dynamic pressure
60 min t
5
10
[/cm-3]
density
Bz =-2 nT
Bz =-10 nT
60 min t
5
10
[/cm-3]density
Bz =0nT
Bz =-10 nT
tpulse -5m
tpulse +5m
tpulse +10m
tpulse +15m
tpulse +20m
Bz = -2 nT Nsw = 5/cc
Bz = -2 nT Nsw = 10/cc
Red (dawn to dusk )Blue (dusk to dawn)
Time evolution of the electric field in XY planeSimulation ResultsSimulation Results
Bz = -10 nT Nsw = 5/cc
Bz = -10 nT Nsw = 10/cc
30 20
-60 X 0
-20
Y 0
(RE)
a) a large viscous cell near the magnetopause but very little convection in tail
b) large convection in tail
Condition 1
tpulse -5m
tpulse +5m
tpulse +10m
tpulse +15m
tpulse +20m
Time evolution of perpendicular current density
Bz = -2 nT Nsw = 5/cc
Bz = -2 nT Nsw = 10/cc
Bz = -10 nT Nsw = 5/cc
Bz = -10 nT Nsw = 10/cc
X=-15RE X=-15RE
large viscous cell
Cross section in tail
tpulse -5m
tpulse +5m
tpulse +10m
tpulse +15m
tpulse +20m
Time evolution of plasma pressure
Bz = -2 nT Nsw = 5/cc
Bz = -2 nT Nsw = 10/cc
Bz = -10 nT Nsw = 5/cc
Bz = -10 nT Nsw = 10/cc
Location of Bowshock : 15.4 -> 14RE
Location of Dayside Magnetopause :11.5RE -> 10RE
Location of Bowshock : 14.8RE ->13RE
Location of Dayside Magnetopause :11RE -> 9RE
X (RE)
Y
(RE)
20
-20
30 -60
Bz = -10 nT, Nsw = 5/cc
Bz = -10 nT, Nsw = 10/ccBz = -2 nT , Nsw = 5/ccBz = -2 nT, Nsw = 10/cc
Vx > 0 tailwardVx < 0 earthward
Tail reconnection 14~15 RE
Tail reconnection ~11 RE
Earthward flow has ~50 km/s, while the tailward flows ~150km/s (20 min)
Earthward flow has ~300 km/s, while the tailward flows ~400km/s (10min)
little change J (J~4) increases J ~ 3times J
(P~28)(P~100)
Bz = -10 nT Nsw = 10/cc
Bz = -2 nT Nsw = 5/cc
Condition 3
tpulse -5m
tpulse +5m
tpulse +10m
tpulse +15m
tpulse +20m
Time evolution of the electric field and plasma pressure in XY plane
Compress by dynamic pressure
Small convection in tail
Location of Bowshock : 14.8RE ->13.5RE
Location of Dayside Magnetopause :11RE -> 9RE
Bz = -2 nT , Nsw = 5/cc
Bz = -10 nT, Nsw = 10/cc
Tail reconnection ~12 RE
Earthward flow has ~75 km/s, while the tailward flows ~150km/s (20 min)
(P~40)
little change J (J~6)
Vx > 0 tailwardVx < 0 earthward
SummarySummary
We have studied magnetospheric phenomena by 3D MHD simulation when the IMF Bz and solar wind components exist.
a) IMF Bz=-2nT, density=5/cm-3 -> IMF Bz =-2nT, density =10/cm-3
A large viscous cell near the magnetopause but very little convection in tail Tail reconnection occur at 14-15RE after 20 min Earthward flow ~ 40 km/s and tailward flow ~150km/s)
Location of Bowshock ~14RE and Magnetopause location ~ 10RE
Small tail current
b) IMF Bz=-10nT, density=5/cm-3 -> IMF Bz=-10nT, density = 10/cm-3
A large convection in tail (after 15 min) Tail reconnection occur at ~11 RE
Earthward flow ~300 km/s, while the tailward flows ~400km/s (10min) Bowshock ~ 13RE and Magnetopause ~9RE
Tail current increase about 3times
Condition 1
Condition 3IMF Bz=-2nT, density=5/cm-3 -> IMF Bz=-10nT, density = 10/cm-3
very little convection in tail (after 20 min) Tail reconnection occur at ~12 RE
Earthward flow ~70 km/s, while the tailward flows ~150km/s Location of Bowshock ~ 13.5RE and Magnetopause ~9RE
Small tail current
Thank you very much for your attention
tpulse -5m
tpulse +5m
tpulse +10m
tpulse +15m
tpulse +20m
Bz = -2 nT Nsw = 5/cc
Bz = -2 nT Nsw = 10/cc
Bz = -10 nT Nsw = 10/cc
Different pulse condition
tpulse -5m
tpulse +10m
tpulse +15m
tpulse +20m
Bz = -2 nT Nsw = 5/cc
Bz = -10 nT Nsw = 5/cc
Red (dawn to dusk )Blue (dusk to dawn)
Time evolution of the electric fieldSimulation ResultsSimulation ResultsBz = -2 nT Nsw = 10/cc
Bz = -10 nT Nsw = 10/cc
a) very little convection in tail
b) little convection in tail
30 20
-60 X 0
-20
Y 0
(RE)
Condition 2
Bz = -10 nT Nsw = 10/cc
Bz = -2 nT Nsw = 5/cc
Bz = 0 nT Nsw = 5/cc
Bz = -10 nT Nsw = 10/cc
Condition 3 Condition 4