A large‐scale traveling ionospheric disturbance during the magnetic storm of 15 September 1999

Abstract

[1] Using a comprehensive data set and model calculations, we have investigated a prominent large-scale traveling ionospheric disturbance (LSTID) observed in Japan ($37°-16°MLAT) on 15 September 1999, during a recovery phase of sequential storms. The LSTID was detected at 2300-2400 LT (1400-1500 UT) as an enhancement of the 630-nm airglow intensity (50!350 R), a decrease in the F layer virtual height (at 2 MHz, 360!200 km), an enhancement of f o F 2 (6!8 MHz), and an enhancement of GPS total electron content ($1.0 Â 10 16 m À2). Multipoint and imaging observations of these parameters show that the LSTID moved equatorward over Japan with a velocity of $400-450 m/s. From a comparison with the Sheffield University Plasmasphere-Ionosphere Model (SUPIM) we conclude that an enhancement (250-300 m/s) of poleward neutral wind (that is propagating equatorward) caused these observational features of the LSTID at midlatitudes. To investigate generation of the LSTID by auroral energy input, we have used auroral images obtained by the Polar UVI instrument, magnetic field variations obtained at multipoint ground stations, and the empirical Joule heating rate calculated by the assimilative mapping of ionospheric electrodynamics (AMIE) technique. Intense auroral energy input was observed at 0800-1100 UT (4-6 hours before the LSTID), probably causing equatorward neutral wind at lower latitudes. It is likely that the poleward wind pulse that caused the observed LSTID was generated associated with the cessation of this equatorward wind. The effect of Lorentz force is also discussed.

Storm induced large scale TIDs observed in GPS derived TEC

“…by Prölss and Jung (1978) and Jin et al (2008). However, strong northward winds, which were described by Shiokawa et al (2002) and Shiokawa et al (2003) analysing the geomagnetic storm on the 31 March 2001 conflict with this idea indicating that more detailed investigation is necessary. The 2-D-Fourier analyses showed that the LSTID wave fronts induced by ionospheric storms mainly propagate from North to South in Europe.…”

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

“…5 indicates that during the TIDs of October 2003 electrojet currents were enhanced at auroral latitudes. Shiokawa et al (2002) have associated energy deposited in the auroral oval with the initiation of meridionally propagating gravity waves. These authors calculated the amount of high latitude Joule heating and Lorentz force.…”

“…This computer software uses the satellite biases as reported by the University of Bern and calculates the receiver bias minimizing the TEC variability observed between 02:00 and 06:00 LT. TEC curves corresponding to each satellite pass and for each of the 263 receivers were then fitted to a 4th order polynomial to filter out the diurnal variability and to evaluate TEC perturbations (TECP) containing time scales of 3 h or less. Our method is different than the algorithm used by Shiokawa et al (2002) that estimates the unperturbed TEC level by removing a 2-h running average, or the procedure employed by Nicolls et al (2004) that calculates the unperturbed TEC value using a 4-h running average for several latitude-longitude bins. We claim that our derivation of the TEC perturbations reflects quite well the variability of the integrated number density due to the transit of large-scale gravity waves.…”

“…Recently, GPS TEC measurements have detected the passage of atmospheric gravity waves (AGW) at mid and high latitudes (Ho et al, 1998a;Saito et al, 1998;Shiokawa et al, 2002), improved understanding of the dynamics of the magnetically-disturbed mid-latitude ionosphere (Basu et al, 2005), and helped the forecast of the onset of equatorial plasma irregularities (Valladares et al, 2001). The first studies of AWG using GPS receivers employed 150+ globally distributed receivers to indicate the existence of small TEC enhancements developing simultaneously at both north and south auroral regions (Ho et al 1998a, b).…”

“…The amplitude of the perturbation structures was found to be 1 TEC unit (TECU), the wavelengths up to 300 km, and with a phase velocity of order 100 m/s. Shiokawa et al (2002) used 1000+ GPS receivers, an all-sky imager, a scanning photometer, and three sounders, all installed in Japan, to study the dynamics, propagation and source of large-scale TIDs (LSTID). Shiokawa et al (2002Shiokawa et al ( , 2003 concluded that the 630.0 nm airglow intensifications, foF2 and TEC perturbations were the response to an enhancement of the poleward neutral wind associated Published by Copernicus Publications on behalf of the European Geosciences Union.…”