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

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 !!

Polar Cusp

Ambipolar Diffusion~300km

Eambipolar

Electron heating

Ion outflow

Auroral region

Upward accelerated ions

Height>1000 km

Injection of O+ into the Magnetosphere

Dayside Nightside

Gazey et al. 1996

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.

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

Case 1: 23rd Aug 2002

~11 MLT

High electron temperature

Up flow of O+

LobeSheet

Enhanced density ratio ~60% in bl

No O+ in cps

AE index shows very low activity

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?

7th Oct. 2002

~10 MLT

Electron heating

Weak upflow

Due to plasmasheet motion

Energetic O+

in plasma sheet

O+ enhancement

Low energy population in bl

Enhanced ratioonly in ps

AE index shows significant activity near ~8 UT

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

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

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

Satellite data analysis: Wenlong Liu, Rashmi Rawat, Tarun Pant

Modelling and comparisons: Rong Liu, Liu Yuan Li, Guo Xiaocheng

Task Assignment

Thanks !!!!