# A Multiscale Approach to Geomagnetic Storm Morphology Analysis Based on DMA Activity Measures
## 3 Results and Discussion
### Discussion  
The 32.71 nT \(B_{z}\) peak at 05:48 UT, 15 May 2005, during the Storm 1 (Figure 6a) is characterized by a positive zone (Figure 6b) on the energy activity measure plot (starting from \(p=10\)) and on the length activity measure plot; its consequent abrupt decrease is displayed as a wider zone along all the \(p\) values. The corresponding time moment is marked with an arrow. At the same time, the \(B_{y}\) was also subject to disturbances related to  
Figure 5: The geomagnetic data and solar wind parameters during a geomagnetic storm of August 2018: HCN observatory \(X\) component (**a**), IMF \(B_{y}\) (**b**) and \(B_{z}\) (**c**) components, solar wind flux speed (**d**) and proton density (**e**). the shockwave arrival to the magnetosphere frontal part that were quite simultaneous with the \(B_{z}\) characteristic disturbances. However, the decreases on it--the first one from 10:08 and the second on, more intensely, from 14:28 to 19:47 UT--generally do not correlate with the \(B_{z}\) behavior (as seen in Figure 2), as the \(B_{z}\) remained positive and slightly decreasing during 15 May 2005 and then was close to zero during the whole recovery phase, except for an abrupt decrease on 16 May 2005 before noon (also marked with an arrow in Figure 6a). Two mentioned \(B_{y}\) decreases correspond to zones of positive sign on the activity measure plots. The first decrease is revealed by a relatively large zone at low \(p\) values (from 0 to 10) continuing as a thin zone at higher \(p\) values up to \(p=45\). The second decrease is revealed as a wider zone on all \(p\) values from 0 to 50, with its widest part at the lowest \(p\) values. The SSC signal (seen on the \(X\) component in Figure 6c) corresponds to a positive zone on the activity measure plot (Figure 6d) at the moment of the shockwave impact on the magnetosphere front. Similar features of the plasma speed and density data are characterized by similar positive zones on the activity measure plots. The proton density data show the density increase (from 6 to 33 n/cc) at the SSC moment, also matching the flux speed increase from 400 to 800 km/s (and then it gradually increased even to 1029 km/s). The increases in the flux speed are also shown as local positive zones. Slight increases and decreases in the proton density during the main storm phase are also shown as positive and negative  
Figure 6: The \(B_{z}\) IMF component (**a**) and the \(X\) magnetic field component from the HON observatory (**c**) during a geomagnetic storm of May 2005. Below each component is the plot of its activity measure (**b**,**d**) based on the “Energy” indicator. short-time zones, respectively. These plots are not shown in this figure, but we will provide the corresponding plots for other storms to display the activity measure behavior for the plasma speed and proton density data). The energy activity measure plots for the time series corresponding to Storm 2 (Figure 7a,c) show an agreement for the fragments corresponding to the SSC, the main storm phase and the beginning of the recovery phase. Similar sequences of segments indicating extreme dynamics are seen for \(B_{z}\) (Figure 7b), \(B_{y}\) and proton density plots for these periods. The solar wind speed time series (Figure 7c) displays some differences after the SSC; however, generally the activity measure plot for this time series (Figure 7d) repeats the basic features corresponding to the main phase of the storm and several local disturbances on the recovery phase (15-16 December 2006), marked with arrows, as in the previous case. During Storm 3 (22-29 June 2015), the IMF components alternated within the range of tens of nano-Teslas, but the crucial moments of the storm evolution (the beginning and the end of the main storm phase) are again marked for both \(B_{z}\) and \(B_{y}\) activity measure plots and agree well with the corresponding \(X\) data plotted in Figure 4a.