Revisiting the Variation of the Ionospheric Irregularities in the Low Latitude Region of China Based on Small Regional Geodetic GNSS Station Network

Abstract

The rate of total electron content index (ROTI) and loss of lock (LoL) from global navigation satellite system (GNSS) observations are an important data source for ionospheric scintillation study. However, there are certain limitations of these data in ionospheric scintillation study, and clearing these limitations is important to understand the results from these data. In this paper, the variation of the ionospheric scintillation is revisited based on LoL and ROTI from a spatial dense GNSS network in the low latitude region of China. Via a priori knowledge of scintillation morphology, the method to determine the baseline ROTI for discriminating quiet and disturbed conditions is provided, and the abnormal data of ROTI and LoL unrelated to ionosphere are found and eliminated. Results show that the data examination is necessary. Using the qualified ROTI and LoL, the morphological variations of ionospheric irregularities are revisited. The temporal variation of ROTI and LoL are generally consistent, but there are some discrepancies. The maximum LoL occurrence is at about 21:00 LT, it is between 20:00 and 23:00 LT for ROTI. For spatial distribution, both parameters reach maximum occurrence in the southwest direction, but LoL is more concentrated. The azimuth range of maximum occurrence is 180–190° for LoL and 210–220° for ROTI. Statistically, the correlation between LoL occurrence and ROTI value from observation of single GNSS station is relatively good when ROTI <5 TECU/min, but it becomes worse when ROTI >5 TECU/min. However, their correlation can be greatly improved when data are averaged among all the stations.