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Vol. 15 (2012 year), No. 2

Romanovskaya Yu.V., Namgaladze A.A., Zolotov O.V., Starikova N.A., Lopatiy V.Z.
Searching for seismo-ionospheric earthquakes precursors: Total electron content disturbances before 2005-2006 seismic events

During earthquakes preparation periods significant disturbances in the ionospheric plasma density are often observed. These anomalies are caused by lithosphere-atmosphere-ionosphere interaction, particularly by the seismic electric field penetrating from the ground surface into the ionosphere. The seismic electric field produces electromagnetic ЕВ drift changing plasma density over the epicenter region and magnetically conjugated area. The paper is devoted to analysis of regular Global Positioning System observations and revelation of seismo-ionospheric precursors of earthquakes in Total Electron Content (TEC) of the ionosphere. Global and regional relative TEC disturbances maps (%) have been plotted for 2005-2006 M6, D<60 km seismic events and analyzed in order to determine general features of precursors. The obtained results agree with the recent published case-study investigations.

(in English, стр.5, fig. 2, tables. 0, ref 29, Adobe PDF, Adobe PDF 0 Kb)

Vol. 15 (2012 year), No. 3

Knyazeva M.A., Romanovskaya Yu.V., Namgaladze A.A.
Numerical modeling of the electron density enhancements in the night-time ionospheric F2-layer

The middle-latitude enhanced electron density regions (EEDRs) in the night-time ionospheric F2-layer have been investigated using the global numerical Upper Atmosphere Model (UAM) and the empirical ionospheric model IRI-2001. The mechanism of formation, seasonal and latitudinal-longitudinal variations of the EEDRs has been studied. It has been shown that two types of the EEDRs exist on the geomagnetic foF2 maps: 1) winter type with maxima in the latitudinal and diurnal foF2 variations and 2) summer type with the maximum in the latitudinal variation only. Formation of both types of the EEDRs is explained by the corresponding seasonal variations of the thermospheric wind. The physical mechanism of the EEDRs forming is based on the joint action of the plasma flows from the plasmasphere and the neutral wind inducing transportation of the ionospheric plasma along the geomagnetic field lines. The Weddell Sea Anomaly and the analogous phenomenon observed in the Northern Hemisphere have been explained.

(in English, стр.14, fig. 7, tables. 0, ref 56, Adobe PDF, Adobe PDF 0 Kb)