Apart from being used for plasma physics, the HF facility near Tromsø, Norway, can be used to perturb the ionosphere at various heights in different ways, thereby giving information about the ionosphere. The co-located incoherent scatter radars are probably the most powerful instrument for probing the ionosphere, but HF techniques can complement the radars and even have some advantages. The pri...

This paper describes the results of a preliminary study to determine the e€ective heating and cooling time constants of ionospheric currents in a simulated modulated HF heating, `beam painting' con®guration. It has been found that even and odd harmonics of the fundamental ELF wave used to amplitude modulate the HF heater are sourced from di€erent regions of the ionosphere which support signi®ca...

[1] Thunderstorm clouds may discharge directly to the ionosphere in spectacular luminous jets – the largest electric discharges of our planet. The properties of these “giants,” such as their polarity, conductivity, and currents, have been predicted by models, but are poorly characterized by measurements. A recent observation of a giant, fortuitously illuminated by an unusual sprite discharge in...

Ionospheric electron density data from the Sondrestrom incoherent scatter radar (ISR) have been used to characterize the structure of the F region ionosphere during ground-based LF/MF/HF receiver observations of natural ionospheric radio emissions known as auroral roar. In five out of six cases, the F region ionosphere has significant horizontal Ne gradient scale lengths (IVN/NI mi• < 120 km, m...

The Wide Area Augmentation System (WAAS) will provide real-time differential GPS corrections and integrity information for aircraft navigation use. The most stringent application of this system will be precision approach, where the system guides the aircraft to within a few hundred feet of the ground. Precision approach operations require the use of differential ionospheric corrections. WAAS mu...

The Naval Research Laboratory (NRL) Sami2 is Another Model of the Ionosphere (SAMI2) and Sami3 Also a (SAMI3) ionosphere/plasmasphere codes have shown that thermosphere composition winds significantly affect H + outflows from topside ionosphere. In particular, O density inhibits upward diffusion ionosphere F layer, especially during solar maximum conditions. addition, quiet-time latitudinal ext...

The ionosphere is the largest remaining error source affecting GPS. It also has some of the least predictable spatial and temporal variations. As such the ionosphere becomes the determining factor in system performance for WAAS. Because the ionosphere cannot be observed at all places simultaneously, the confidence bound, termed the Grid Ionospheric Vertical Error (GIVE), can only be determined ...

An isolated plasma sheet flow burst took place at 22:02 UT, 1 September 2002, when the Cluster footpoint was located within the area covered by the Magnetometers-Ionospheric Radars-All-sky Cameras Large Experiment (MIRACLE). The event was associated with a clear but weak ionospheric disturbance and took place during a steady southward IMF interval, about 1 h preceding a major substorm onset. Mu...

An isolated plasma sheet flow burst took place at 22:02 UT, 1 September 2002, when the Cluster footpoint was located within the area covered by the Magnetometers-Ionospheric Radars-All-sky Cameras Large Experiment (MIRACLE). The event was associated with a clear but weak ionospheric disturbance and took place during a steady southward IMF interval, about 1 h preceding a major substorm onset. Mu...