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Measurements of total electron content (TEC) using 263 GPS receivers locatedin the North and South America continents are presented to demonstrate thesimultaneous existence of traveling ionospheric disturbances (TID) at high,mid, and low latitudes, and in both Northern and Southern Hemispheres. TheTID observations pertain to the magnetically disturbed period of 29–30 October2003 also known as the Halloween storm. The excellent quality of theTEC measurements makes it possible to calculate and remove the diurnalvariability of TEC and then estimate the amplitude, wavelength, spectralcharacteristics of the perturbations, and the approximate velocity of theAGW. On 29 October 2003 between 17:00 and 19:00 UT, there existed a sequence ofTEC perturbations (TECP), which were associated with the transit ofatmospheric gravity waves (AGW) propagating from both auroral regions towardthe geographic equator. A marked difference was found between the northernand southern perturbations. In the Northern Hemisphere, the preferredhorizontal wavelength varies between 1500 and 1800 km; the propagationvelocity is near 700 m/s and the perturbation amplitude about 1 TEC unit(TECu). South of the geographic equator the wavelength of the TECP is aslarge as 2700 km, the velocity is about 550 m/s, and the TECP amplitude is 3TECu. Concurrently with our observations, the Jicamarca digisonde observedvirtual height traces that exhibited typical features that are associatedwith TIDs. Here, it is suggested that differences in the local conductivitybetween northern and southern auroral ovals create a different Joule heatingenergy term. The quality of these observations illustrates the merits of GPSreceivers to probe the ionosphere and thermosphere

Simultaneous observation of traveling ionospheric disturbances in the Northern and Southern Hemispheres