Title: IMF Control of Dayside Magnetospheric Convection

Speaker: Sheng-Hsien Chen

Abstract:

Recent observations of the plasmasphere by the remote-sensing instruments 
on IMAGE spacecraft depicted for the first time global pictures of the 
plasmasphere at various geomagnetic activities. Phenomena such as the 
plasmaspheric extensions, e.g., plasma tails, or void channels reveal more 
rapid changes than previously thought of the plasmaspheric morphology 
responding to the ionospheric refilling and draining processes and the 
global magnetospheric convection. For example, the plasma tails, instead of 
discrete detachments, extended continuously from the main body of the 
plasmasphere to the distances beyond the geosynchronous orbit could form 
within few hours instead of days. The extension of the plasma tails toward 
dayside could provide a mechanism in feeding the cold ionospheric 
populations to the magnetopause. But how the plasma tails extend beyond the 
geosynchronous orbit to the outer magnetosphere and near the magnetopause 
where the reconnection process, which is believed to govern the global 
magnetospheric convection, actually occurs? We will present global pictures 
of the magnetospheric convection pattern in the dayside outer magnetosphere 
as a function of IMF clock angles using the plasma measurements from TIDE 
on Polar. TIDE can detect extremely cold (~1 eV) ions which velocity moment 
can be used to approximate the ExB drift paths of zero temperature charge 
particles and, therefore, the velocities of magnetic field lines. The data 
set is a collection of in-situ measurements between the years of 2000-2003 
when Polar apogee paths were in the dayside. The averages of plasma 
convection patterns in the equatorial plane at different categories of IMF 
clock angles will be presented.