The coupled ionosphere–thermosphere–plasmasphere system is very complex. The study of its interrelationships during geomagnetically disturbed conditions is an especially challenging task.Significant progress has been achieved during the last few years in developing comprehensive theoretical models to describe its global behaviour.Moreover, more simple, specialized numerical modelling of some specialaspects of storm behaviour and/or regional models have contributedto the progress in this field.This paper summarizes recent developments in upper ionosphereand plasmasphere storm studies and modelling.From an observational point of view the upper ionosphere/plasmasphereregion is well reflected in radio beacon measurements providing the totalelectron content (TEC). The development of space-based radio navigation systems such as GPS offersnew opportunities to derive TEC on both regional and global scale.Combining TEC with ionosonde data enables the variability of the shape of the electron density distribution during storms to be studied.We present some examples of co-ordinated investigation,made during the CEDAR storm study intervals.

Geomagnetic storm effects on the topside ionosphere and plasmasphere : A compact tutorial and new results

. An overall statistical study of night-time enhancements of NmF2 has been carried out. All available foF2 observations since 1955 at 53 ionosonde stations distributed worldwide in the latitude range f geom = 15° - 60° were used in the analysis. More than 200 000 station-nights of data were analysed. This large data base allowed us to study seasonal, solar cycle and spatial variations of the NmF2 nighttime enhancements. Both pre-midnight and post-midnight NmF2 peaks demonstrate distinct variations with geophysical conditions, indicating different physical mechanisms responsible for their formation. Key words. Ionosphere (mid-latitude ionosphere, ionosphere-magnetosphere interactions) Radio science (ionospheric physics)

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Global morphology of night-time Nm F2 enhancements

Some F2-layer effects during the January06-11,1997 cedar storm period as observed with theMillstoneHill incoherent scatter facility

Mechanism of the post-midnight winter night-time enhancements in NmF2 over Millstone Hill during 14-17 January 1986

The solar eclipse effects on the ionosphere are very complex. Except for the ionization decay due to the decrease of the photochemical process, the couplings of matter and energy between the ionosphere and the regions above and below will introduce much more disturbances. Five ionosondes in the Northeast Asia were used to record the midlatitude ionospheric responses to the solar eclipse of 20 May 2012. The latitude dependence of the eclipse lag was studied first. The foF2 response to the eclipse became slower with increased latitude. The response of the ionosphere at the different latitudes with the same eclipse obscuration differed from each other greatly. The plasma flux from the protonsphere was possibly produced by the rapid temperature drop in the lunar shadow to make up the ionization loss. The greater downward plasma flux was generated at higher latitude with larger dip angle and delayed the ionospheric response later. The waves in the foEs and the plasma frequency at the fixed height in the F layer are studied by the time period analytic method. The gravity waves of 43–51 min center period during and after the solar eclipse were found over Jeju and I-Cheon. The northward group velocity component of the gravity waves was estimated as ~108.7 m/s. The vertical group velocities between 100 and 150 km height over the two stations were calculated as ~5 and ~4.3 m/s upward respectively, indicating that the eclipse-induced gravity waves propagated from below the ionosphere.

N. Jakowski

Papers

About the nature of the Night-time Winter Anomaly effect (NWA) in the F-region of the ionosphere