GPS-derived total electron content response for the Bastille Day magnetic storm of 2000 at a low mid-latitude station

Abstract

First steps toward the development of a vertical Total Electron Content (VTEC) storm-time correction empirical ionospheric model, equivalent to the STORM model for the peak concentration of the F2 region (Araujo-Pradere and Fuller-Rowell, 2002, Araujo-Pradere et al., 2002), are currently in progress in the NOAA's Space Environment Center (SEC). The program to obtain VTEC, the SEC's Win TEC Project (Anghel and Codrescu, 2002), use the RINEX (Receiver Independent Exchange for-mat) files to derive the vertical TEC from the delay of the Global Position System (GPS) signals.
With a maximum Dst of -287.6 (maximum a_p = 400), the storm of July 2000, known as the Bastille Day storm, has been one of the most intense perturbations in the present solar cycle. The response of the TEC at a low mid-latitude station, as obtained from the delay in code and phase of the GPS signals, is analyzed for this storm. The vertical TEC at ccv3 (Cape Canaveral, Florida, latitude 28.46 N, longitude 279.45 E) suffered a sudden increase, over 250% with respect to quiet conditions, for the first day of the storm, followed by a sharp negative gradient, and a slow recovery. The picture is further complicated by the presence of very steep gradients, responsible for the degradation of the GPS positioning accuracy.