); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (XL.) Zhaohua Shi  
1 National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; huangluxu@[EMAIL_ADDRESS] (L-H.); [EMAIL_ADDRESS] (S.S.); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (XL.) Zhaohua Shi  
1 National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; huangluxu@[EMAIL_ADDRESS] (L-H.); [EMAIL_ADDRESS] (S.S.); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (XL.) Zhaohua Shi  
1 National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; [EMAIL_ADDRESS] (L-H.); [EMAIL_ADDRESS] (S.S.); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (XL.) Zhaohua Shi  
1 National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; huangluxu@[EMAIL_ADDRESS] (L-H.); [EMAIL_ADDRESS] (S.S.); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (XL.) Zhaohua Shi  
1 National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; huangluxu@[EMAIL_ADDRESS] (L-H.); [EMAIL_ADDRESS] (S.S.); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (XL.) Zhaohua Shi  
1 National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; huangluxu@[EMAIL_ADDRESS] (L-H.); [EMAIL_ADDRESS] (S.S.); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (XL.) Zhaohua Shi  
1 National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; huangluxu@[EMAIL_ADDRESS] (L-H.); [EMAIL_ADDRESS] (S.S.); cym@ntsc.ac.cnand high-frequency signals [2]. Although the impact on the ionosphere in low-latitude regions is relatively less pronounced, it still results in fluctuations that affect global positioning systems (GPS) and satellite communication. [PERSON] et al. (2011) noted that ionospheric disturbances in low-latitude regions, primarily manifested as changes in Total Electron Content (TEC), can cause short-term disruptions to satellite communications [3]. Additionally, [PERSON] and [PERSON] (2018) pointed out that ionospheric variations in low-latitude areas can significantly degrade signal quality for high-precision navigation systems, such as GPS, during solar storms [4]. The transmitting station (Shangqiu) and receiving station (Xi'an) in this study are both located in the middle-latitude region. Moreover, the receiving station, in comparison to the transmitting station, is situated in the Earth-ionosphere waveguide separation zone, where low-frequency signals are more susceptible to electromagnetic layer disturbances. The central frequency of low-frequency time-code signals primarily ranges between 40 kHz and 80 kHz, which are radio signals with strong long-range propagation capabilities. Their propagation path includes both ground waves and sky waves. Ground waves propagate along the Earth's surface, while sky waves rely on reflection between the Earth's surface and the ionosphere. As a result, these signals are highly sensitive to changes in the ionospheric electron density and refractive index. When the ionosphere is disturbed, such as by an increase or decrease in electron density, significant changes occur in the propagation path, attenuation characteristics, and signal strength of low-frequency signals. Therefore, low-frequency signals are not only an important means of communication but also provide highly sensitive data support for studying ionospheric disturbances. The propagation of low-frequency time-code signals is highly dependent on the reflective properties of the ionosphere, and disturbances caused by solar flares often result in signal offset, delay, and attenuation, thereby affecting their reliability and accuracy.