The Global Navigation Satellite System (GNSS) observations with global coverage and high temporal and spatial resolution, provide abundant and high-quality Earth-ionosphere observations. By calculating the total electron content (TEC), estimations from GNSS observables global and regional ionosphere TEC morphology can be further investigated. For the multiple constellation case, the numbers of ionosphere pierce points (IPP) has increased tremendously, and it is worth studying the features of the GNSS derived TEC under geomagnetic storms to show the benefits of multiple constellation measurements. With the Multi-GNSS Experiment (MGEX) observation data, ionosphere TEC responses to the geomagnetic storm on the 22 June 2015 were well studied. TEC perturbations were discovered, accompanied by ionosphere irregularities concentrating in high and middle latitudes. Through analysis of multi-GNSS observations, the Rate of TEC Index (ROTI) perturbations were proved to be generated by the geomagnetic storm, with simultaneous behaviors at different local times around the world, also indicating ionosphere scintillation. The ionosphere spatial gradient was also discussed with two short baseline MGEX sites; the maximum ionosphere gradient of 247.2 mm/km was found, due to ionosphere irregularity produced by the storm. This research has discussed ionosphere responses to geomagnetic storms with multi-GNSS data provided and has analyzed the availability of multi-GNSS observations to investigate ionosphere irregularity climatology. The proposed work is valuable for further investigation of GNSS performances under geomagnetic storms.

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One of the adverse impacts of scintillation on GNSS signals is the loss of lock status, which can lead to GNSS geometry and visibility reductions that compromise the accuracy and integrity of navigation performance. In this paper the loss of lock based on ionosphere scintillation in this solar maximum phase has been well investigated with respect to both temporal and spatial behaviors, based on GNSS observatory data collected at Weipa (Australia; geographic: 12.45° S, 130.95° E; geomagnetic: 21.79° S, 214.41° E) from 2011 to 2015. Experiments demonstrate that the percentage of occurrence of loss of lock events under ionosphere scintillation is closely related with solar activity and seasonal shifts. Loss of lock behaviors under ionosphere scintillation related to elevation and azimuth angles are statistically analyzed, with some distinct characteristics found. The influences of daytime scintillation and geomagnetic storms on loss of lock have also been discussed in details. The proposed work is valuable for a deeper understanding of theoretical mechanisms of—loss of lock under ionosphere scintillation in global regions, and provides a reference for GNSS applications in certain regions at Australian low latitudes.

The high-speed solar winds stream (HSSWS) generated by coronal hole can produce large interplanetary magnetic field magnitude oscillations, leading to high latitude geomagnetic disturbances, and ionospheric responses as well. This paper has analyzed the global ionospheric total electron content (TEC) and rate of TEC index (ROTI) responses during the high speed solar winds stream occurred from 23 to 29 August, 2010. Ground Global Navigation Satellite System (GNSS) network was mainly used to investigate ionosphere TEC and ROTI behaviors. It has revealed that high latitudes and middle latitudes ionosphere suffered most during this event, with hemisphere asymmetry characteristics. Both TEC variations and ionosphere irregularities were analyzed. The HSSWS event brings to strong ionosphere irregularities represented by large ROTI enhancements at high latitudes. The concentrated ionosphere irregularities were closely related to the intensity of Auroral Electrojet enhancement activities. The ROTI enhancements at high latitudes, including polar cap, aurora, and sub-aurora are also influenced by solar zenith angle; all the prominent ROTI increments are observed in the ranges between 70 • and 110 • solar zenith angles; while the ROTI enhancements at low latitudes and equator are mostly found in the ranges between 130 • and 170 • solar zenith angles. The ionosphere disturbance triggered by the HSSWS is also noticed by some remarkable changes of F2 layer peak height. The work is contributing to the understanding of the theoretical coupling mechanism between high speed solar winds stream and magneto-ionosphere responses and provides a reference for space weather analysis and forecasting under similar events.INDEX TERMS High speed solar winds stream, ionospheric TEC, ionosphere irregularity.