The November 2004 superstorm: Comparison of low-latitude TEC observations with 
LLIONS model results. Matthew A. Hei, Cesar E. Valladares, J. Vincent Eccles. 
 
In recent years, distributed arrays of ground-based GPS receivers have been used 
to probe the ionosphere with great success. Measures of TEC so obtained, in 
conjunction with physics-based models, can specify the plasma distribution over 
wide regions of space. However, during geomagnetic storm conditions, and/or when 
receiver spacings are too great, accurately mapping the plasma distribution in 
three dimensions over a wide geographic area is extremely difficult. In such 
cases, GPS arrays may still be used to study the primary drivers of stormtime 
electrodynamics. Here, we study the primary drivers of the November 7-11 
superstorm, using a chain of GPS receivers in South America. In particular, we 
use the TEC distribution, in conjunction with the LLIONS (Low-Latitude 
IONospheric Sector) model and other observations, to draw conclusions regarding 
the relative roles of the zonal E-field at the geomagnetic equator, meridional 
neutral winds, and neutral composition changes in shapin 
 g the low-latitude stormtime plasma distribution. High-quality vertical drift 
data from the Jicamarca ISR is used to drive the LLIONS model. Since the 
Jicamarca data begins on the 9th, and the largest recorded drifts occur on the 
9th and the 10th, the focus of this talk is on these two days.