Multi-Scale Ionospheric Anomalies Monitoring and Spatio-Temporal Analysis during Intense Storm

Abstract

The ionosphere is a significant component of the geospace environment. Storm-induced ionospheric anomalies severely affect the performance of Global Navigation Satellite System (GNSS) Positioning, Navigation, and Timing (PNT) and human space activities, e.g., the Earth observation, deep space exploration, and space weather monitoring and prediction. In this study, we present and discuss the multi-scale ionospheric anomalies monitoring over China using the GNSS observations from the Crustal Movement Observation Network of China (CMONOC) during the 2015 St. Patrick’s Day storm. Total Electron Content (TEC), Ionospheric Electron Density (IED), and the ionospheric disturbance index are used to monitor the storm-induced ionospheric anomalies. This study finally reveals the occurrence of the large-scale ionospheric storms and small-scale ionospheric scintillation during the storm. The results show that this magnetic storm was accompanied by a positive phase and a negative phase ionospheric storm. At the beginning of the main phase of the magnetic storm, both TEC and IED were significantly enhanced. There was long-duration depletion in the topside ionospheric TEC during the recovery phase of the storm. This study also reveals the response and variations in regional ionosphere scintillation. The Rate of the TEC Index (ROTI) was exploited to investigate the ionospheric scintillation and compared with the temporal dynamics of vertical TEC. The analysis of the ROTI proved these storm-induced TEC depletions, which suppressed the occurrence of the ionospheric scintillation. To improve the spatial resolution for ionospheric anomalies monitoring, the regional Three-Dimensional (3D) ionospheric model is reconstructed by the Computerized Ionospheric Tomography (CIT) technique. The spatial-temporal dynamics of ionospheric anomalies during the severe geomagnetic storm was reflected in detail. The IED varied with latitude and altitude dramatically; the maximum IED decreased, and the area where IEDs were maximum moved southward.

Eyjafjallajökull Volcanic Ash 2010 Effects on GPS Positioning Performance in the Adriatic Sea Region

“…This is consistent with the vertical ionospheric delay characterisation during quiet ionospheric conditions, when southern reference stations encountered higher values of both vertical ionospheric delays compared to the northern stations. This may be explained by the difference in the energy received both directly from the Sun and from the processes of free electrons transfer from subequatorial region [16,33]. However, the evidence for increased vertical ionospheric delay in days 110-115 suggests another, slightly less dominant ionospheric process that caused the increase in the maximum vertical ionospheric values.…”

“…The broadcast model (i.e., Klobuchar) was applied for ionosphere correction and broadcast data and the utilisation of broadcast ionospheric (Klobuchar) and Saastamoinen model for tropospheric correction, as depicted in Figure 2. This may be considered a common practice for an ordinary, single-frequency GPS receiver [32,33]. The RTKLIB GPS receiver returned position estimates, as well as the position estimation errors calculated using the known position of the reference station in a tabular data format suitable for further processing [30].…”

“…Time series of VTEC values (equivalent to GPS ionospheric delay) were further processed using our own R-based software. Time series of VTEC values observed during the European volcanic ash 2010 crisis were compared with the normal VTEC values observed at the same station sites in quiet-space weather and ionospheric conditions, in order to assess the contribution of volcanic ash to the overall GPS ionospheric delay [7,33]. In addition, a due consideration was given to the global status of the geomagnetic and ionospheric conditions, using the reference data from [37], in order to distinguish volcanic ash affects from potential effects of global geomagnetic and ionospheric storms.…”

Study of Ionospheric Bending Angle and Scintillation Profiles Derived by GNSS Radio-Occultation with MetOp-A Satellite

“…Another metric commonly used to analyze the ionospheric scintillations is the rate of change of TEC (ROT) [45]. It can be used to describe the phase fluctuations and is obtained based on the following equation:…”