Characterizing Quiet Time Variability in the Equatorial Ionosphere

During periods of quiet geomagnetic activity there is considerable, unexplained variability in the density and structure of the equatorial ionosphere. The hope is to predict the response to geomagnetic storms, it first must be able to predict conditions in the ionosphere during periods of minor solar forcing. To address this, a tool is being developed to quantitatively analyze the observed variability in South American Total Electron Content (TEC) maps during geomagnetically quiet periods. The goal is to create a tool that will sort the data provided by the Low-Latitude Ionospheric Sensor Network (LISN) in South America. The tool will look for patterns in TEC and try to correlate patterns with solar activity or terrestrial weather. We present the qualitatively categorized TEC patterns from December 2011 and the quantitative tool being created to sort through the larger set of several years of TEC data. This investigation also helps illustrate the need for more observations of potential drivers of ionospheric variability, and how the Ionospheric Connection Explorer (ICON) will help to improve our understanding of this important part of our Earth-Sun system.