Magnetosphere-Ionosphere coupling processes reflected in Cluster II and EISCAT data Outflow of ionospheric ions Wenlong Liu, Rashmi Rawat, Rong Liu, Liu Yuan Li, Guo Xiaocheng, Tarun Kumar Pant Project Tutor : Prof. Stephan Buchert Regional Workshop for Space Physicists from South-East Asia 13th May 2004

Presence of O+ ions has been shown at near and far magnetosphere through satellite observations in the nightside !! Where do ionospheric O+ go?? -ring current? -ps boundary layer? -central plasma sheet? -downstream solar wind? Do they play a role for magnetospheric plasma processes such as magnetic reconnection??

Eambipolar Polar Cusp Ion outflow Electron heating Ambipolar Diffusion ~300km

Upward accelerated ions 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.

Present Study and the measurements used: 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 High electron temperature Up flow of O+ ~11 MLT

Lobe Sheet

Enhanced density ratio ~60% in bl No O+ in cps

AE index shows very low activity

Case-I 23rd August 2002 , quiet day a. A strong ionospheric outflow of O+ from the cusp is seen with 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 Electron heating Weak upflow ~10 MLT

Energetic O+ in plasma sheet Due to plasma sheet motion O+ enhancement Low energy population in bl O+ enhancement

Enhanced ratio only 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 eV Probably 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 events Backward 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 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

Task Assignment Satellite data analysis: Wenlong Liu, Rashmi Rawat, Tarun Pant Modelling and comparisons: Rong Liu, Liu Yuan Li, Guo Xiaocheng

Thanks !!!!