Small-scale anomalies in total electron content(TEC)gradients can significantly affect the accuracy of regional ionospheric models and ground-based augmentation systems(GBAS).Therefore,to improve the accuracy of regional ionospheric modeling and GBAS navigation and po-sitioning,further study on small-scale TEC spatial gradients is crucial.To investigate these gradi-ents,data from the BeiDou geostationary Earth orbit(GEO)satellites collected by global naviga-tion satellite system(GNSS)receivers in the Guilin area from 2019 to 2022 are used for the analy-sis,focusing on the TEC spatial gradients of the low-latitude region of China(23°N 107.9°～113.1°E).Based on the TEC observations from three adjacent BeiDou GEO satellite puncture points on the ground(numbered sequentially from west to east as C02,C03,and C01),two TEC spatial gradient observation areas of about 300 km in scale(107.9°～110.3°E and 110.3°～113.1°E)are established for C02-C03 and C03-C01.Statistical results show that the spatial gradient in the C02-C03 area is predominantly west-ward;whereas in the C03-C01 area,the spatial gradient is eastward from January to April and from September to December,and westward from May to August.This indicates that there are seasonal variations in the spatial gradients between adjacent areas,revealing a significant local effect on me-dium-and small-scale spatial gradients.Furthermore,local time differences are not the main cause of spatial gradients.In years of high solar activity,when the background TEC is higher,spatial gradient events are more likely to occur.The biannual variation in the occurrence rate of gradient events reflects the biannual anomaly of the TEC.The frequency rate of spatial gradient events is similar under different geomagnetic conditions.
Partial effectCarrier phase smoothing pseudorangeTotal electron content(TEC)Spatial gradient
NETL
NSTL
万方数据
