Magnetosphere-Ionosphere coupling processes reflected in Cluster II and EISCAT data
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Transcript of Magnetosphere-Ionosphere coupling processes reflected in Cluster II and EISCAT data
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Magnetosphere-Ionosphere coupling processes reflected in Cluster II and EISCAT data
Project Tutor : Prof. Stephan Buchert
Wenlong Liu, Rashmi Rawat, Rong Liu, Liu Yuan Li, Guo Xiaocheng, Tarun Kumar Pant
Regional Workshop for Space Physicists from South-East Asia 13th May 2004
Outflow of ionospheric ions
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Where do ionospheric O+ go??-ring current?
-ps boundary layer?-central plasma sheet?
-downstream solar wind?
Do they play a role for magnetospheric plasma processessuch as magnetic reconnection??
Presence of O+ ions has been shown at near and far magnetosphere through satellite observations in the nightside !!
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Polar Cusp
Ambipolar Diffusion~300km
Eambipolar
Electron heating
Ion outflow
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Auroral region
Upward accelerated ions
Height>1000 km
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Injection of O+ into the Magnetosphere
Dayside Nightside
Gazey et al. 1996
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Dayside ambipolar outflow has low energy (~eV)
Mechanisms for further energisation are unclear!
Dayside outflow is relatively persistent and can reach high flux.
Auroral outflow accelerates efficiently to ~keV energies above > 1000km
Occurs only during substorm activity
It can not be seen directly with EISCAT radar.
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One should have simultaneous measurements in polar cusp,auroral ionosphere and magnetosphere!
Present Study and the measurements used:
a. EISCAT radar data from day side
b. Cluster II data from the tail
(c. Polar Satellite -TIM data)
Geomagnetic indices
Period : August – October 2002
Two representative events have been found and are being presented
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Case 1: 23rd Aug 2002
~11 MLT
High electron temperature
Up flow of O+
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LobeSheet
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Enhanced density ratio ~60% in bl
No O+ in cps
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AE index shows very low activity
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Case-I 23rd August 2002 , quiet daya. A strong ionospheric outflow of O+ from the cusp is seenwith EISCAT
b. Cluster CIS detects enhanced O+ of few keV in the plasma sheet boundary layer
How is O+ accelerated ??
c. No major substorm activity seen
d. No O+ in the central plasma sheet
In this case O+ is unable to reach ring current/inner magnetosphere??
“Prove” that boundary layer plasma is from open field-lines?
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7th Oct. 2002
~10 MLT
Electron heating
Weak upflow
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Due to plasmasheet motion
Energetic O+
in plasma sheet
O+ enhancement
Low energy population in bl
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Enhanced ratioonly in ps
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AE index shows significant activity near ~8 UT
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Case-II 7th October 2002 Disturbed day
a. O+ in boundary layer at low energy ~100 eVProbably due to the dayside outflow (similar to Case-I)
b. Significant O+ in the central plasma sheet
time of flight effect ?? Probably due to auroral, substorm related outflow
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Goals for the future work
a. More quatitative modeling by combining field line tracing and convection model.
Forward tracing of EISCAT eventsBackward tracing of Cluster events
b. More quantitative estimation of the frequency and flux of outflow from the dayside.
c. Investigation of the variation of density and flux of O+ ions in different magnetospheric regions like the boundary layer, central plasma sheet and ring current
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Required data resources: 1. EISCAT radar for ionospheric outflow flux and velocity in the high latitude region 2. Cluster satellite in the magnetotail and plasma sheet region
3. IMAGE, POLAR, DMSP, AKEBONO, TC-2
Event selection and preliminary investigations : December 2004
Required Modeling resources: Magnetic field models like Tsyganenko models and electric field models for tracing the ion trajectories.
Model comparisons : April 2005
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Satellite data analysis: Wenlong Liu, Rashmi Rawat, Tarun Pant
Modelling and comparisons: Rong Liu, Liu Yuan Li, Guo Xiaocheng
Task Assignment
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Thanks !!!!