Natural hazards including earthquakes, volcanic eruptions and tsunamis have been significant threats to humans throughout recorded history. Global navigation satellite systems (GNSS; including the Global Positioning System (GPS)) receivers have become primary sensors to measure signatures associated with natural hazards. These signatures typically include GPS-derived seismic deformation measure...

[1] The Jet Propulsion Laboratory/University of Southern California Global Assimilation Ionospheric Model (JPL/USC GAIM) uses two data assimilation techniques to optimally combine ionospheric measurements with the physics model: a sparse, traditional Kalman filter to estimate the three-dimensional density state, and a four-dimensional variational approach (4DVAR) to estimate ionospheric drivers...

Integrity monitoring and reliable detection of the ionospheric spatial gradient is of importance for various fields including total electron content modeling, radio communication and radar, and differential GNSS applications such as landing, departure and surface operations at an airport. In this contribution, we investigate the precision and the integrity of the ionospheric spatial gradient es...

A study of ionospheric data recorded at Slough/Chilton, UK, from 1935 to 2012, has revealed longterm changes in the relative strength of the annual and semiannual variability in the ionospheric F2 layer critical frequencies. Comparing these results with data from the southern hemisphere station at Stanley in the Falkland Islands between 1945 and 2012 reveals a trend that appears to be anti-corr...

At the Low-Frequency Array (LOFAR)(Planet. Space Sci. (2004) these proceedings) frequencies (HF/VHF), extraterrestrial radiation experiences substantial propagation delay as it passes through the ionosphere. The adaptive calibration technique to be employed by LOFAR will use signals from many known bright radio sources in the sky to estimate and remove the effects of this delay. This technique ...

In addition to absolute orbit determination information, many current and future space missions require onboard relative navigation solutions between multiple satellites. GNSS is ideal for satisfying such requirements because of its long-term stable accuracy and global availability. It is well known that of the various error sources in the GNSS observations, the ionospheric path delay is one of...

The CUTLASS Finland HF radar has been operated in conjunction with the EISCAT Tromsù RF ionospheric heater facility to examine a ULF wave characteristic of the development of a ®eld line resonance (FLR) driven by a cavity mode caused by a magnetospheric impulse. When the heater is on, striating the ionosphere with ®eld-aligned ionospheric electron density irregularities, a large enough radar ta...

A comparative study is carried out between a semi-empirical low-latitude ionospheric model (SLIM). including calculated 01 630 nm airglow emission intensities predicted by the SLIM model, with ionospheric and r>I 630 nm airglow measurements carried out at Cachoeira Paulista (22.7”S, 45.O”W; geomag. 11.9”S), Brazil. A long series of regular measurements of ionospheric F-region peak electron dens...

The emergence of China's Beidou, Europe's Galileo and Russia's GLONASS satellites has multiplied the number of ionospheric piercing points (IPP) offered by GPS alone. This provides great opportunities for deriving precise global ionospheric maps (GIMs) with high resolution to improve positioning accuracy and ionospheric monitoring capabilities. In this paper, the GIM is developed based on multi...

This article describes the current status of the Deep Space Network advanced systems research into ionospheric calibration techniques, based on Global Positioning System (GPS) data. A GPS-based calibration system is planned to replace the currently used Faraday rotation method by 1989. The SERIES receiver system used in this research determines the differential group delay of signals transmitte...