Extremely large ionospheric gradients can pose a potential integrity threat to the users of ground-based augmentation systems (GBAS). A better understanding of the ionospheric behavior (not limited to that during extreme ionospheric activity) is important in the design and operation of GBAS to meet its integrity and availability requirements. A tool for long-term ionosphere monitoring was devel...

Analysis of data for Washington and Watheroo indicates differences in the relationship between føF2 and sunspot number for the current and preceding sunspot cycles. The sunspot number is therefore not entirely satisfactory as an index for ionospheric variations. Consequently, ionospheric data for the current cycle only should be used in preparing ionospheric radio propagation predictions whenev...

Ionospheric disturbances are known to have adverse effects on the satellite-based communication and navigation. One particular type of ionospheric effects, observed during major geomagnetic storms and threatening the integrity performance of both ground-based and space-based GNSS augmentation systems, is the sharp increase/decrease in the ionospheric delay that propagates in horizontal directio...

We review the recent paper by Su et al. (2013). Using Global Position System and Global Ionospheric Maps data, Su et al. claimed to have found ionospheric precursors a few days before the 16 October 1999 Hector Mine, California, earthquake. They proposed that this type of analysis of ionospheric data may be useful for locating forthcoming large earthquakes. In this Comment, we reexamine these d...

Nearly two years of 2-min resolution data and 7to 21-s resolution data from the CUTLASS Finland HF radar have undergone Fourier analysis in order to study statistically the occurrence rates and repetition frequencies of pulsed ionospheric ̄ows in the noon-sector high-latitude ionosphere. Pulsed ionospheric ̄ow bursts are believed to be the ionospheric footprint of newly reconnected geomagnetic ...

We present simultaneous current and wideband electric field waveforms at 380 km associated with upward flashes initiated from the Säntis Tower. To the best of the authors’ knowledge, the presented dataset in this study includes the first simultaneous records of lightning currents and associated fields featuring ionospheric reflections, and the longest distance at which lightning fields have bee...

The effect of magnetospheric substorms on the global ionospheric convection pattern is widely debated. Discussed here, is a study made of ionospheric electric currents, co-incident with plasma convection at the time of substorm onset, using the HF radars of the Super Dual Auroral Radar Network (SuperDARN), and the global array of ground magnetometers. Preliminary results are presented, which ut...

The success of precise GPS positioning over long baselines depends on the ability of resolving the integer phase ambiguities when short observation time spans are required. The ionosphere is the major error source for these kind of positioning problems and due to the current maximum of solar activity the ionospheric delay errors in GPS signals can be much larger than in periods of minimum activ...

The SuperDARN radars map high-latitude ionospheric plasma drift velocities by measuring the Doppler frequency shift of HF signals scattered by decameter electron density irregularities. In many cases the ionospheric returns are contaminated by strong scatter from the ground or sea surface. In this paper we develop and test a two-component fitting algorithm to separate ionospheric and surface sc...

By using a magnetosphere-ionosphere (M-I) coupling model of polar cap arcs [Zhu et al., 1993], a systematic model study of the effects of ionospheric background conductivity on the formation of polar cap arcs has been conducted. The variations of the ionospheric background conductivity in the model study cover typical ionospheric onditions, including solar minimum, solar maximum, winter, and su...