Global Response of the Ionosphere to Atmospheric Tides Forced from Below: Recent Progress Based on Satellite Measurements

This paper provides an overview on the recent progress in studying the ionospheric response to atmospheric tides forced from below. The global spatial structure and temporal variability of the atmospheric temperature tides and their ionospheric responses are considered on the basis of modern satellite-board data (COSMIC and TIMED). The tidal waves from the two data sets have been extracted by one and the same data analysis method. The similarity between the lower thermospheric temperature tides and their ionospheric responses provides evidence for confirming the new paradigm of atmosphere-ionosphere coupling. This paper provides also new experimental results which give an explanation why the WN4 and partly WN3 longitude structures are so prominent pattern in the ionosphere. These results present evidence indicating that the WN4 (WN3) structure is not generated only by the DE3 (DE2) tide as it has been often assumed. The DE3 (DE2) tide remains the leading contributor, but the SPW4 and SE2 (SPW3, DW4 and SE1) waves have their effects as well in a way that the ionospheric response becomes almost double (1.5 time stronger). The paper presents also the global distribution and temporal variability of the sun-synchronous 24-h (DW1), 12-h (SW2) and 8-h (TW3) electron density oscillations. It has been shown that while the latitude and altitude structure of the ionospheric SW2 response is predominantly shaped by the migrating SW2 tide forced from below the DW1 response is mainly due to daily variability of the photo-ionization. The peculiar vertical structure of the ionospheric TW3 response, that shows downward/upward phase progression, calls for further study of the physical processes shaping this ionospheric response.     

Local ionospheric electron density profile reconstruction in real time from simultaneous ground-based GNSS and ionosonde measurements

The purpose of the LIEDR (local ionospheric electron density profile reconstruction) system is to acquire and process data from simultaneous ground-based total electron content (TEC) and digital ionosonde measurements, and subsequently to deduce the vertical electron density distribution above the ionosonde’s location. LIEDR is primarily designed to operate in real time for service applications and, for research applications and further development of the system, in a post-processing mode. The system is suitable for use at sites where collocated TEC and digital ionosonde measurements are available. Developments, implementations, and some preliminary results are presented and discussed in view of possible applications.     

Planetary wave coupling of the atmosphere–ionosphere system during the Northern winter of 2008/2009

This paper presents the global spatial (latitude and altitude) structure and temporal variability of the ∼23-day ionospheric zonally symmetric (s = 0) planetary wave (PW) seen in the Northern winter of 2008/2009 (October 2008–March 2009). It is shown that these ∼23-day ionospheric oscillations are forced from PWs propagating from below. The COSMIC ionospheric parameters f_oF2 and h_mF2 and electron density at fixed altitudes and the SABER temperatures were utilized in order to define the waves which are present simultaneously in the atmosphere and ionosphere. The long-period PWs from the two data sets have been extracted through the same data analysis method. The similarity between the lower thermospheric ∼23-day (s = 0) temperature PW and its ionospheric electron density response provides valuable and strong experimental evidence for confirming the paradigm of atmosphere–ionosphere coupling.