## 3 Results and Analyses  
In February 2014, four Earth-directed coronal mass ejections (CMEs) triggered a highly complex, multiphase geomagnetic storm. The first CME arrived on 15 February, and then the other three on 19, 20, and 23 February. During this period, there were detected 11 small halo CMEs starting from the Sun (website SOHO/LASCO HALO CME catalogue, [[https://cdaw.gsfc.nasa.gov/CME_list/halo/halo.html](https://cdaw.gsfc.nasa.gov/CME_list/halo/halo.html)]([https://cdaw.gsfc.nasa.gov/CME_list/halo/halo.html](https://cdaw.gsfc.nasa.gov/CME_list/halo/halo.html)), accessed date: 1 March 2021). Solar flares are classified according to their brightness intensity (I) in the X-ray wavelength range (1-8 A): X-class (\(>\)10\({}^{-4}\) W/m\({}^{2}\)), M-class (10\({}^{-5}\) \(>\) I \(>\) 10\({}^{-4}\) W/m\({}^{2}\)), C-class (10\({}^{-6}\) \(>\) I \(>\) 10\({}^{-5}\) W/m\({}^{2}\)), and B-class (\(<\)10\({}^{-4}\) W/m\({}^{2}\)) flares. Since the particles travel at velocities of approximately 400 km/s, a fast gust of solar wind can take 2 to 4 days to reach Earth after it leaves the Sun. For example, two M-class flares on 12 February occurred at 6 and 16 h UT (M3.7 and M2.1, respectively), which reached Earth's environment on 15 February, at approximately 13 h UT. On 19 February, a minor geomagnetic storm caused by the small impact on 15 February was still in progress, and the upcoming events reenergized the existing state, creating a complex multiphase storm. Usually, geomagnetic storms begin with a sudden impulse after the arrival of an interplanetary shock ([[http://www.obsebre.es/en/rapid](http://www.obsebre.es/en/rapid)]([http://www.obsebre.es/en/rapid](http://www.obsebre.es/en/rapid)), 23 January 2022), namely a sudden storm commencement (SSC). Figure 1 shows the SSC on 15 February, which is coincident with a period of increased plasma pressure followed by peaks of southward IMF. At this point, the combination of an increased solar wind speed with the oscillation of the IMF B\({}_{x}\) and solar wind velocity results in enhancements of E\({}_{y}\) and E\({}_{m}\). Subsequently, when there is solar wind pressure on the magnetosphere, variations in the geomagnetic SYM-H index result from density variations of the trapped magnetospheric particle population. In this figure, the solar wind proton density, plasma pressure, temperature, and the plasma Beta parameter, as well as the alpha/proton density ratios, are included. All these variables showed a clear variability after the SSC. Then, the SYM-H started to decrease on 19 February at 03:00 UT. This was the starting point of a storm derived from an M1.1 CME released from the Sun on 16 February. However, the resulting storm effects lacked classical SSC characteristics. Regardless of the weak detected shock and slow decrease in SYM-H, the high-speed solar wind (HSSW) entered the magnetosphere due to the southward IMF, creating strong magnetospheric convection, which is reflected with an enhancement of the Am index up to 92 nT (similar to the Kp index, the Am index can be used as a proxy to evaluate the severity magnetospheric convection). Then, the SYM-H dropped down to \(-112\) nT at 09:00 UT, and a rapid northward turning of the IMF resulted in a rapid recovery of SYM-H to \(-40\) nT in approximately 12 h.  
The third SSC occurred at approximately 04:00 UT on 20 February. This storm resulted from a solar filament eruption observed on 18 February ([[https://spaceweather.com/](https://spaceweather.com/)]([https://spaceweather.com/](https://spaceweather.com/)) accessed date: 2 February 2022) and produced a SYM-H drop from \(-40\) nT down to \(-86\) nT at 12:00 UT on 20 February. The SYM-H index recovered rapidly up to \(-40\) nT at 19:00 UT and then gradually increased to 4 nT until the onset of the fourth storm at 08:00 UT on 23 February, followed by a minimum of \(-56\) nT at 00:00 UT on 24 February. This slow-moving M3.0 CME was ejected from the Sun on 20 February.