## 8 Conclusions  
We use the BDS-GEO satellites and ionosondes to investigate the disturbance responses of the low-latitude ionosphere in the eastern hemisphere during the geomagnetic storm in August 2018. The upper and lower bounds are calculated by GIM TEC to detect the positive or negative signatures from the BDS GEO TEC. The BDS GEO satellites can effectively detect the high-resolution variations of ionospheric TEC, compared with the GIM model during the long-term monitoring. During the main phase of the storm, the large positive disturbance signatures are detected on 26 August over all the selected stations at low-latitude regions, and the magnitude of disturbance signatures vary from 14.1 to 25.1 TECU. During the recovery phase of the storm, the local persistent positive signatures are observed on 27-28 August. The increment of \(f_{o}F_{2}\) and \(h_{m}F_{2}\) are also observed by using ionosondes. The in situ electron density Ne measured by the Swarm A and C satellites also verifies the presence of the uplift of the F2 layer observed from ionosonde stations during this geomagnetic storm. The thermospheric composition variation possibly has a direct impact on the disturbance responses of ionospheric TEC. The positive disturbance signatures at low latitudes during the recovery phases of the storm are mainly attributed to the enhancement of the O/N\({}_{2}\) ratio and the uplift of the F layer. [PERSON] and [PERSON] conceived and designed the experiments; [PERSON] and [PERSON] performed the experiments; [PERSON] and [PERSON] wrote the paper; [PERSON] and [PERSON] analyzed the data; [PERSON] and [PERSON] revised the paper. All authors have read and agreed to the published version of the manuscript. This research is supported by the National Key Research & Development Program (No. 2017 YFE0131400), the National Natural Science Foundation of China (No. 42074045), the Key Laboratory for Digital Land and Resources of Jiangxi Province, East China University of Technology (No. DLLJ202104), and the National Natural Science Foundation of China (No. 41761089). **Indexed Consent Statement:** Not applicable. **Data Availability Statement:** MGEX data are available from [[https://cddis.nasa.gov/archive/gnss/data/campaign/mpgex/](https://cddis.nasa.gov/archive/gnss/data/campaign/mpgex/)]([https://cddis.nasa.gov/archive/gnss/data/campaign/mpgex/](https://cddis.nasa.gov/archive/gnss/data/campaign/mpgex/)) (accessed on 12 August 2021). The ionosondes data are provided by GIRODidbase ([[https://ulcar.uml.edu/](https://ulcar.uml.edu/)]([https://ulcar.uml.edu/](https://ulcar.uml.edu/)) accessed on 12 August 2021). The SANYA ionosonde data are provided by the Beijing National Observatory of Space Environment, Institute of Geology and Geophysics Chinese Academy of Sciences through the Geophysics center, National Earth System Science Data Center ([[http://wdc.geophys.ac.cn/](http://wdc.geophys.ac.cn/)]([http://wdc.geophys.ac.cn/](http://wdc.geophys.ac.cn/)) accessed on 12 August 2021). The Swarm satellite data are obtained from the European Space Agency ([[https://swarm-diss.eo.esa.int/](https://swarm-diss.eo.esa.int/)]([https://swarm-diss.eo.esa.int/](https://swarm-diss.eo.esa.int/)) accessed on 12 August 2021). The O/N\({}_{2}\) ratio data from GUVI are provided by the website ([[http://guvitimed.jhuapl.edu/](http://guvitimed.jhuapl.edu/)]([http://guvitimed.jhuapl.edu/](http://guvitimed.jhuapl.edu/)) accessed on 12 August 2021). The OMNI data are obtained from the GSFC/SPDF OMNIWeb interface ([[http://omniweb.gsfc.nasa.gov/](http://omniweb.gsfc.nasa.gov/)]([http://omniweb.gsfc.nasa.gov/](http://omniweb.gsfc.nasa.gov/)) accessed on 12 August 2021). Figure 9: Variation of the interplanetary electric field during 24–28 August 2018. **Acknowledgments:** The authors acknowledge IGS for providing MGEX data, GIRODidbase for providing ionosonde data, the European Space Agency for providing Swarm satellite data, GUVI for providing O/N\({}_{2}\) ratio data, and OMNIWeb for providing OMNI data.