Abstract
In this study, we present results from an investigation of the spatial
variability of geomagnetic disturbances (GMDs) occurring during large
(minimum Dst ≤ −100 nT) geomagnetic storms. Expanding on a previous
study, we quantify the equatorward expansion of extreme GMDs as a
function of KP and a new Dst-derived range index, the Disturbance
Threshold Indicator (Dti). We then assess the largest GMDs as a function
of MLT and MLAT during these storms for different levels of geomagnetic
activity and empirically identify intrinsic patterns and systematic
variations.