Isolated ionospheric disturbances as deduced from global GPS network

E L Afraimovich,E I Astafieva,S V Voyeikov

doi:10.5194/angeo-22-47-2004

E L Afraimovich, E I Astafieva + Show 1 more

Open Access

https://doi.org/10.5194/angeo-22-47-2004

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Journal: Annales Geophysicae	Publication Date: Jan 1, 2004
Citations: 34	License type: CC BY 3.0

Affiliation: Institute of Solar-Terrestrial Physics

Abstract

Abstract. We investigate an unusual class of medium-scale traveling ionospheric disturbances of the nonwave type, isolated ionospheric disturbances (IIDs) that manifest themselves in total electron content (TEC) variations in the form of single aperiodic negative TEC disturbances of a duration of about 10min (the total electron content spikes, TECS). The data were obtained using the technology of global detection of ionospheric disturbances using measurements of TEC variations from a global network of receivers of the GPS. For the first time, we present the TECS morphology for 170 days in 1998–2001. The total number of TEC series, with a duration of each series of about 2.3h (2h18m), exceeded 850000. It was found that TECS are observed in no more than 1–2% of the total number of TEC series mainly in the nighttime in the spring and autumn periods. The TECS amplitude exceeds the mean value of the "background" TEC variation amplitude by a factor of 5–10 as a minimum. TECS represent a local phenomenon with a typical radius of spatial correlation not larger than 500km. The IID-induced TEC variations are similar in their amplitude, form and duration to the TEC response to shock-acoustic waves (SAW) generated during rocket launchings and earthquakes. However, the IID propagation velocity is less than the SAW velocity (800–1000m/s) and are most likely to correspond to the velocity of background medium-scale acoustic-gravity waves, on the order of 100–200m/s. Key words. Ionosphere (ionospheric irregularities, instruments and techniques) - Radio science (ionospheric propagation)

Highlights

Of the known ionospheric irregularities of a different class, mid-latitude isolated ionospheric disturbances (IIDs) stand out as a highly unusual type
Karasawa et al (1985) noticed from a long-term recording of the signal from the geostationary MARISAT satellite at 1.5 GHz frequency which was synchronous with amplitude S-scintillations, there occur similar-appearing changes to the rotation angle of the polarization plane that are proportional to a corresponding disturbance of total electron content (TEC)
It is evident from the figure that the selected typical TEC variations such as TECS are identical and shifted by a certain amount of delay, which makes it possible to calculate the velocity and direction of the IID that causes the observed TEC variations

Summary

Introduction

Of the known ionospheric irregularities of a different class, mid-latitude isolated ionospheric disturbances (IIDs) stand out as a highly unusual type. IIDs are detected when recording amplitude and phase scintillations of transionospheric radio signals in the form of rarely occurring single aperiodic negative impulses with a duration from a few to several tens of seconds (Karasawa, 1985). To name this uncommon type of scintillation Karasawa (1985) seems to be the first to coin the term “spikes-type” (S-) scintillations. It is customary to associate the occurrence of S-type oscillations with diffraction or interference from small-scale irregularities, “blobs” and “bubbles”, generated in the ionosphere

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