Coordinated measurements of F region plasma patches were conducted on February 3/4, 1984, from Thule and Sondrestrom, Greenland. Optical, ionosonde, amplitude scintillation, total electron content (TEC), and incoherent scatter radar measurements were combined to reveal several new aspects of the structure and transport of these localized regions of enhanced F region ionization. For the first time these patches were directly tracked flowing in the antisunward direction over distances of 3000 km from the center of the polar cap to the poleward edge of the auroral oval. Quantitative measurements of TEC show increases of 10–15 TEC units within the patches, above a background polar cap value of 5 TEC units. Amplitude scintillation measurements show the presence of ionospheric irregularities through the entire patch, with a weak indication of stronger scintillation on the trailing (or E × B unstable) edge.

Abstract. Simulated observations of total electron cornera (TEC) along ray paths from Global Positiomng System (GPS) satellites have been used to validate the estimation of TEC using GPS measuremeres. The Sheffield Umversity plasmasphere ionosphere model (SUPIM) has been used to create electron densities that were integrated along ray paths from actual configurations of the GPS constellation. The resultant slant electron contents were then used as inputs to validate the self-calibration of pseudo-range errors (SCORE) process for the deternfination of TEC from GPS observations. It is shown that if the plasma resides only in the ionosphere below 1100 km, then the SCORE procedure determines the TEC to a high degree of accuracy. When the contribution of the electrons in the protonosphere above 1100 km is included, the analysis results in TEC estimates that are high by some 2 TEC umts (TECU) for conditions appropriate to European nfidlatimdes at solar nfimmum However, if a restriction is placed in the analysis on use of observations equatorward of the station, then allowance can be made for the effect of the proionosphere. It is shown that with appropriate selection of the boundary for the observations, TEC can be estimated by SCORE to better than 1 TECU for the conditions of the simulation. Sample results are included from actual experimemal observations using GPS to demonstrate the effect of compensation for the protonosphenc plasma.

Abstract. Global Positioning System (GPS) satellites have orbital altitudes of about 20,200 km, while satellites in the Navy Ionospheric Monitoring System (NIMS) constellation are in circular orbits at heights of about 1100 kin. Independent measurements of the electron content in the ionized atmosphere can be made using the radio signals from both satellite constellations. Differences between the two estimates can be related to the electron content on the GPS ray paths above 1100 kin, through the tenuous plasma of the protonosphere. Results are reported from some 21 months of simultaneous observations of both GPS and NIMS transmissions at a European midlatitude station at solar minimum. It is shown that the average differences between the electron contents measured by the two systems are in broad agreement with the predictions from an earlier modeling study of the effects of the protonosphere on GPS total electron content. The expected influence of ray path / flux tube geometry and the rapid depletion and slow refilling of the protonosphere in response to geomagnetic storm activity can be seen in the averaged measurements.

Pryse, Sian; Kersley, L.; Malan, D.; Bishop, G. J., 'Parameterization of the main ionospheric trough in the European sector, Radio Science (2006) 41 pp.RS5S14 RAE2008Measurements of total electron content, obtained by monitoring satellite transmissions at stations in the United Kingdom during a period of 12 months, have been used to characterize the structure and dynamics of the main ionospheric trough in terms of a set of defined parameters. The primary aim of the investigation was to represent the position and shape of the trough in such a way that the experimental observations can be used for direct comparison and validation of ionospheric models.Peer reviewe

Coordinated radio and optical measurements of the structure and dynamics of the postsunset equatorial ionosphere were conducted on October 1, 1994, from Agua Verde, Chile (11.3°S magnetic latitude (MLat)). The measurements clearly show a north‐south aligned undulation or ripple on the bottomside of the F layer at 2000 LT, appearing as an eastward propagating decrease in the 630.0‐nm airglow, resembling a traveling ionospheric disturbance in the digital portable ionosonde measurements and causing a total electron content decrease in the Global Positioning System (GPS) satellite measurements. The initial development of this feature, toward the east and away from the magnetic equator, took place in an otherwise smooth, unstructured ionosphere. Spread F began to develop in the ionograms at 2020 LT, and, at this same time, local onset of satellite signal scintillation was detected using the multiple ray paths throughout the sky available from the GPS satellite constellation transmitting at L band frequencies. UHF scintillation measurements from Ancon, Peru, along the same magnetic field line, show that intense scintillation and ionospheric irregularities had developed over the magnetic equator almost 60 min prior to their development at 11°S MLat. The observations suggest that the east‐west electric field expected to be present within the earlier developed depletion and scintillation region at the magnetic equator mapped along magnetic field lines to lower altitudes and higher latitudes, resulting in an undulation or dome‐shaped structure, before evolving into a fully developed depletion (with associated ionospheric irregularities) all along the magnetic flux tube.