Comparison between 2-D GPS dTEC Data Maps and Digisonde Observations over the South American and Atlantic Regions

While GNSS-derived absolute total electron content (TEC) measurements contain a wealth of information on the state of the ionosphere, certain ionospheric phenomena are most clearly discernable by examining the detrended TEC data instead. Such phenomena include traveling ionospheric disturbances (TIDs) and equatorial plasma bubbles (EPBs). We have developed a TEC data detrending procedure [Pradipta et al., 2015] that is inherently capable of distinguishing between wavelike fluctuations associated with TIDs and deep depletions associated with EPBs. Subsequent 2-D geospatial latitude/longitude mapping of net detrended TEC (dTEC) values from 200 + stations in South America reveal the spatial structures of EPBs over that region (in close alignment with the geomagnetic meridian), and their drift movement throughout the evening. These 2-D latitude/longitude maps of detrended TEC allow us to gain good spatial awareness on the presence of ionospheric irregularities over the area, but some additional validation from independent measurement data would be useful to confirm the data products.