## 1 Introduction  
In recent years, the widespread use of GNSS PNT services [1] has made it increasingly important to enhance the security and reliability of global satellite navigation systems. The ionosphere serves as a crucial pathway for the transmission of satellite carrier signals, forming a link between the near-Earth atmosphere and outer space. The potential threat it poses to the GNSS PNT service is widely recognized. Investigations into ionospheric scintillation hold vital importance in enhancing the reliability of GNSS PNT services. The ionosphere is an atmospheric layer located approximately 60-1000 km above the Earth's surface. The ionosphere is the most exceptional layer of the Earth as it is the most outer one towards outer space. Therefore, the ionosphere can contain important information. As it was discovered by [PERSON] around 1912 [2], the whole of the Earth's atmosphere has played a historical role in the discovery and in the progress of ubiquitous cosmic radiation. The ionosphere consists of atmospheric molecules that are made up of ions and electrons with non-uniformly varying densities, resulting in structural inhomogeneity. When the GNSS carrier signal travels through the irregular ionosphere structure [3], it experiences rapid fluctuations in its time delay, amplitude, and phase. This is known as scintillation [3], which is caused by various factors, including solar activity, magnetic storms, local electric fields, and wave interactions, among others factors [4, 5]. Scintillation can affect the amplitude and phase of the GNSS carrier signal to different extents. This can result in the deterioration of positioning accuracy and continuity performance. Ionospheric scintillation is broadly classified into two types: amplitude scintillation and phase scintillation. Amplitude scintillation results in the rapid disruption of the signal carrier-to-noise ratio, a reduction in the quality of the signal-to-noise ratio, and the halting of signal transmission via satellite [6]. Alternatively, phase scintillation can result in weekly fluctuations in the carrier phase, which could have detrimental effects such as signal loss in severe cases [7; 8]. Many vital civil and military installations are dependent on GNSS systems. Therefore, the creation of effective techniques for identifying ionospheric scintillation has become exceedingly crucial for ionospheric investigation and for improving the precision of GNSS devices. There are numerous factors that influence the intensity of ionospheric scintillation, and among them, geographical location is one of the critical factors. In the case of L-band satellite signals, ionospheric scintillation is notably most severe in the polar and equator regions [9; 10]. Data indicate that satellite communication near the polar and equator regions can be unreliable, with receivers often unable to capture the transmitted signal, resulting in interrupted navigation [11]. Additionally, there is a seasonal trend in the variation in ionospheric scintillation [12] throughout the year, with a higher frequency of occurrences during the spring and autumn equinoxes. The scintillation is particularly intense during the spring equinox. Current research into ionospheric scintillation detection relies heavily on ground-based ionospheric scintillation monitoring (ISM) stations [13; 14]. While these stations offer prolonged and continuous monitoring, their limited geographic coverage means they are unable to capture the diverse range of scintillation features present in different regions. Additionally, the cost of deploying a sufficient number of ground-based ISM stations globally is prohibitively expensive. GNSS radio occultation (RO) [15] is an objective remote sensing approach. It involves receiving electromagnetic wave signals emitted by high-orbiting GNSS satellites and measuring them in the L1 (1575.42 MHz) and L2 (1227.42 MHz) frequency bands via GNSS receivers installed on LEO satellites. When GNSS carrier signals pass through the ionosphere, the radio wave path bends.