The geomagnetic storm of 17–18 March 2015 was caused by the impacts of a coronal mass ejection and a high‐speed plasma stream from a coronal hole. The high‐latitude ionosphere dynamics is studied using arrays of ground‐based instruments including GPS receivers, HF radars, ionosondes, riometers, and magnetometers. The phase scintillation index is computed for signals sampled at a rate of up to 100 Hz by specialized GPS scintillation receivers supplemented by the phase scintillation proxy index obtained from geodetic‐quality GPS data sampled at 1 Hz. In the context of solar wind coupling to the magnetosphere‐ionosphere system, it is shown that GPS phase scintillation is primarily enhanced in the cusp, the tongue of ionization that is broken into patches drawn into the polar cap from the dayside storm‐enhanced plasma density, and in the auroral oval. In this paper we examine the relation between the scintillation and auroral electrojet currents observed by arrays of ground‐based magnetometers as well as energetic particle precipitation observed by the DMSP satellites. Equivalent ionospheric currents are obtained from ground magnetometer data using the spherical elementary currents systems technique that has been applied over the ground magnetometer networks in North America and North Europe. The GPS phase scintillation is mapped to the poleward side of strong westward electrojet and to the edge of the eastward electrojet region. Also, the scintillation was generally collocated with fluxes of energetic electron precipitation observed by DMSP satellites with the exception of a period of pulsating aurora when only very weak currents were observed.

We present a multiinstrumented approach for the analysis of the Arctic ionosphere during the 19 February 2014 highly complex, multiphase geomagnetic storm, which had the largest impact on the disturbance storm‐time index that year. The geomagnetic storm was the result of two powerful Earth‐directed coronal mass ejections (CMEs). It produced a strong long lasting negative storm phase over Greenland with a dominant energy input in the polar cap. We employed global navigation satellite system (GNSS) networks, geomagnetic observatories, and a specific ionosonde station in Greenland. We complemented the approach with spaceborne measurements in order to map the state and variability of the Arctic ionosphere. In situ observations from the Canadian CASSIOPE (CAScade, Smallsat and IOnospheric Polar Explorer) satellite's ion mass spectrometer were used to derive ion flow data from the polar cap topside ionosphere during the event. Our research specifically found that (1) thermospheric O/N₂ measurements demonstrated significantly lower values over the Greenland sector than prior to the storm time. (2) An increased ion flow in the topside ionosphere was observed during the negative storm phase. (3) Negative storm phase was a direct consequence of energy input into the polar cap. (4) Polar patch formation was significantly decreased during the negative storm phase. This paper addresses the physical processes that can be responsible for this ionospheric storm development in the northern high latitudes. We conclude that ionospheric heating due to the CME's energy input caused changes in the polar atmosphere resulting in N_e upwelling, which was the major factor in high‐latitude ionosphere dynamics for this storm.

The processing of measurement data from satelliteconstellations such as Global Navigation Satellite Systems(GNSS), including the well-known Global PositioningSystem (GPS), have been successfully applied to virtuallyall areas of geophysical sciences. In this work, amethod is described where Geographical Information Systems(GIS) are employed to build hourly ionospheric TotalElectron Content (TEC) maps for 2011 over the southernIberian Peninsula. The maps used GPS-derived geometryfreelinear combinations attained from station data fromthe Algarve, Alentejo (Portugal), Andalusia, Murcia andValencia (Spain) regions. Following the construction ofthe ionospheric maps, it was possible to relate these resultsto natural phenomena. The observed phenomena includeddiurnal and seasonal variations: daytime TEC maxima,nighttime TEC peaks, summer TEC value decreases,and spring and fall TEC maxima. After validation of theseperiodic phenomena, detection of non-periodic changes,such as solar flares and tectonic interactions with the ionospherewere attempted. The results showed a TEC increasefollowing a selected solar flare event and a potential TECbuild-up prior to the 2011 Lorca earthquake. Further studiescould open up the possibility of building early warningsystems. The presented methods, based on available softwarepackages, are also of value in monitoring the effect ofthe ionosphere on radio signals, satellite and mobile communication,power grids, and for accurate GNSS navigation.

A new wave propagator that can be used to simulate global navigation satellite systems reflected signals from ocean surfaces is presented. The wave propagator simulates the characteristics of a bistatic scattering system. Simulated GPS ocean surface reflections will be presented and discussed based on different ocean characteristics. The spectra of the simulated surface reflections are analyzed, and the results from the simulations are compared to measured GPS surface reflections. The measurements were performed using a space-qualified GPS receiver placed on a mountain at the Haleakala observatory on the Hawaiian island of Maui. The GPS receiver was during the experiments running in an open-loop configuration. The analysis of both the simulated surface-reflection signals and the measured reflection signals will in general reveal spectral structures of the reflected signals that can lead to extraction of sea surface roughness, surface wind speed, and direction.