Interferometric Synthetic Aperture Radar (InSAR) and the Global Positioning System (GPS) are commonly used to obtain surface topography and surface motions for the study of crustal deformation. Because both of these systems operate from satellites high above the Earth’s surface, the arrival time of the propagating signals is delayed as the signals travel through the Earth’s ionosphere. As a res...

As a preliminary to the studies conducted by the individual Working Groups, a review has been undertaken of topics which are relevant to the space-weather phenomena that can occur. The ways in general that these can influence the state of the ionosphere are discussed. The various changes in propagation parameters that arise on Earth-space and terrestrial radio paths via the ionosphere are liste...

We investigate the effect of halo activity on the electrostatic field measured at ground level. We use electrostatic arguments as well as self-consistent simulations to show that, due to the screening charge in the ionosphere, the distant electrostatic field created by the uncompensated charge in a thundercloud decays exponentially rather than as the third power of the distance. Furthermore, si...

This paper highlights the important role played by the EISCAT radar for verification in the development of tomographic techniques to produce images of ionospheric electron density. A brief review is given of some of the stages in the application of tomographic reconstruction techniques to the ionosphere. Results are presented to illustrate the effectiveness of the method in imaging ionospheric ...

The Local Area Augmentation System (LAAS) is a ground-based differential GNSS system designed to provide precision approach for aircraft landing at a LAASequipped airport. While most anomalies affecting the system can be mitigated in the range domain, positiondomain geometry screening is essential to mitigate threats from anomalous ionosphere spatial gradients. These can potentially cause large...

During the operation of the EISCAT high power facility (heater) at Tromsø, Norway, on 8 October 1998, the FAST spacecraft made electric field and particle observations in the inner magnetosphere at 0.39 Earth radii above the heated ionospheric region. Measurements of the direct current electric field clearly exhibit oscillations with a frequency close to the modulated frequency of heater (∼ 3 H...

[1] We compare the timing and spatial extent of dipolarization with auroral breakup by using magnetic field data (1-min time resolution) from GOES 8 and GOES 9 and global auroral images (37-s frame rate) from the Polar ultraviolet imager. We survey the entire year of 1997 data and obtain 32 unambiguous dipolarization events that had ionospheric footprints within 2 hours in magnetic local time (...

Dissipating planetary waves in the mesosphere/lower thermosphere (MLT) region may cause changes in the background dynamics of that region, subsequently driving variability throughout the broader thermosphere/ionosphere system via mixing due to the induced circulation changes. We report the results of case studies examining the possibility of such coupling during the northern winter in the conte...

The impact of regional-scale neutral atmospheric waves has been demonstrated to have profound effects on the ionosphere, but circumstances under which they generate ionospheric disturbances and seed plasma instabilities are not well understood. Neutral vary from infrasonic <20 Hz gravity with periods order 10 min, for simplicity, hereafter combined common term Acoustic Gravity Waves (AGW...

Methods are developed to determine the refracted propagation paths of high-frequency RF signals in the ionosphere and to determine the sensitivities of these paths to changes of the input model parameters. These techniques are being developed to support the assimilation of data from mono-static and multi-static ionosondes with the goal of improving parameterized estimates of ionosphere electron...