The influence of magnetospheric substorms on high-latitude ionospheric convection

A. Grocott (1), J.A. Wild (2), S.E. Milan (1), T.K. Yeoman (1) 

(1) University of Leicester, UK; (2) Lancaster University, UK
email: a.grocott@ion.le.ac.uk

The primary aim of the recently launched NASA THEMIS mission is to determine the causality of the substorm process.  However, whilst THEMIS will be in a position to make unprecedented in-situ observations of the magnetospheric effects of substorms it will nevertheless provide only local-point measurements.  A fundamental effect of substorms on the coupled magnetosphere-ionosphere system is the global change to the electrodynamics which occurs and this can only be revealed by ionospheric studies.  We have therefore studied the ionospheric flows observed during ~2000 substorms (identified using the far ultra violet imager on board the IMAGE satellite) in an attempt to fully characterise the nature of substorm-associated convection and provide a framework of understanding in which future observations can be interpreted.  The Super Dual Auroral Radar Network (SuperDARN) has provided line-of-sight velocity data from 60 minutes prior to, to 90 minutes following, each substorm onset and these data have then been combined using a global fitting technique to determine statistical convection patterns.  These patterns will be discussed in terms of the global and local response of the convection to substorms of different onset latitudes.