## 2 Data and Analysis  
The _fo_F2 and virtual height of F-region (\(h^{\prime}F\)) data recorded by ionosonde during 2012 were obtained from World Data Centre, Bureau of Meteorology, Australia (online at [[http://www.sws.bom.gov.au/World_Data_Centre](http://www.sws.bom.gov.au/World_Data_Centre)]([http://www.sws.bom.gov.au/World_Data_Centre](http://www.sws.bom.gov.au/World_Data_Centre)), accessed on 22 December 2021). The values of _fo_F2 available online are with scaling up by a factor of 10, and the same values were used in our plots (Figures 1-6). The disturbance storm time (_Dst_) index and _AE_ index data were obtained from World Data Centre, Kyoto University, Kyoto, Japan (online at [[http://www.ssde.u-kigi-kyoto-ac.jp](http://www.ssde.u-kigi-kyoto-ac.jp)]([http://www.ssde.u-kigi-kyoto-ac.jp](http://www.ssde.u-kigi-kyoto-ac.jp)), accessed on 22 December 2021). The southward IMF \(B_{Z}\) values during the main phase of the storms were obtained from OMNI world data center [[https://omniweb.gsfc.nasa.gov/](https://omniweb.gsfc.nasa.gov/)]([https://omniweb.gsfc.nasa.gov/](https://omniweb.gsfc.nasa.gov/)) (accessed on 22 December 2021). Figure 1: Variations of (**a**) _Dst_ index _fo_r the geomagnetic storm, (**b**) hourly values of critical frequency of F\({}_{2}\) layer (_fo_F2) (MHz \(\times\) 10\({}^{-1}\)), (**c**) _\(\Delta\)fo_F2%, and (**d**) virtual height of F layer (\(h^{\prime}F\)) during 30 September–3 October 2012 at Darwin station. The median values of _fo_F2 and \(h^{\prime}F\) parameters are shown by solid black curves in panels (**b**,**d**). Dashed curves in panel (**b**) show the variation of _fo_F2 by \(\pm\) 1 \(\sigma\) (standard deviation). Figure 2: Variations of **(a)**_Dst_ index _for_ the geomagnetic storm, **(b)** hourly values of critical frequency of F\({}_{2}\) layer (\(\theta\)F2) (MHz \(\times\) 10\({}^{-1}\)), **(c)**\(\Delta\)_fo_F2%, and **(d)** virtual height of F layer (\(\mathit{h}^{\prime}F\)) during 30 September–3 October 2012 at Townsville station. The median values of _fo_F2 and \(\mathit{h}^{\prime}F\) parameters are shown by solid black curves in panels **(b,d)**. Dashed curves in panel **(b)** show the variation of _fo_F2 by \(\pm\) 1 \(\sigma\). Figure 3: Variations of (**a**) _Dst_ index _for_ the geomagnetic storm, (**b**) hourly values of critical frequency of F\({}_{2}\) layer (_f_oF2) (MHz \(\times\) 10\({}^{-1}\)), (**c**) \(\Delta\)_f_oF2%, and (**d**) virtual height of F layer (_h_’F_) during 30 September–3 October 2012 at Canberra station. The median values of _f_oF2 and _h_’F parameters are shown by solid black curves in panels (**b**,**d**). Dashed curves in panel (**b**) show the variation of _f_oF2 by \(\pm\) 1 \(\sigma\). Figure 4: Variations of (**a**) _Dst_ index _for_ the geomagnetic storm, (**b**) hourly values of critical frequency of F\({}_{2}\) layer (_f_oF2) (MHz \(\times\) 10\({}^{-1}\)), (**c**) \(\Delta\)_f_oF2%, and (**d**) virtual height of F layer (_l_’_’_F_) during 7–10 October 2012 at Darwin station. The median values of _f_oF2 and _h_’_F_ parameters are shown by solid black curves in panels (**b**,**d**). Dashed curves in panel (**b**) show the variation of _f_oF2 by \(\pm\) 1 \(\sigma\). Figure 5: Variations of (**a**) \(D\)_st_ index _f_or the geomagnetic storm, (**b**) hourly values of critical frequency of F\({}_{2}\) layer (_f_oF2) (MHz \(\times\) 10\({}^{-1}\)), (**c**) \(\Delta\)_f_oF2%, and (**d**) virtual height of F layer (_l_’_f_) during 7–10 October 2012 at Townsville station. The median values of _f_oF2 and _h_’_F_ parameters are shown by solid black curves in panels (**b**,**d**). Dashed curves in panel (**b**) show the variation of _f_oF2 by \(\pm\) 1 \(\sigma\).