## 4 Discussion and Conclusive Remarks
In particular, it has been suggested that positive disturbances with strong afternoon components tend to be critical features of the ionospheric response to the impact of CIR/HSSs in the ionospheric middle latitudes, while these dominate during the declining phase and solar minimum conditions [47]. At first approach, the differences in the ionospheric storm-time response may be attributed to the intensity of the storm events: as CIR/HSSs drive geomagnetic storms of weak to moderate intensity, one would expect the generated neutral composition disturbance zone to be confined to higher latitudes. In any case, it may also be expected that the relative contribution of the ionospheric storm background mechanisms may differ between CME- and CIR/HSSs-driven disturbances, as the result of the differences in the total energy deposition into the auroral atmosphere [55; 56; 57], and the way in which this energy is distributed [58; 15] during different storm scenarios. Of particular importance may be the role of the particle precipitation in the development of the ionospheric response during CIR/HSSs-driven disturbances [47]. The resulting heating may cause large-scale changes to the thermosphere composition, density and circulation (winds) in any case [21; 59], but the rate of the energy deposition may differ between CME and CIR/HSSs cases [60]. It has been reported that the main phase of CME-driven events is characterized by intense but short-lived particle precipitation excursions, while the non-CME cases are characterized by prolonged periods of particle precipitation [47], which in turn may result in the gradual development of the disturbances and the limited extent of the neutral composition disturbance zone. In any case, the clarification of how the upper atmosphere is affected by solar coronal holes still requires the attention of the research community. Present availability in global-scale observations, new models and new analysis methods may facilitate systematic studies. The results, in combination with the output of studies on the CMEs that dominate solar maximum, would complete our understanding of storm time ionospheric response throughout the solar cycle [61], and would significantly advance our prediction capabilities in case it is proven that different storm scenarios need to be addressed differently by ionospheric prediction models [47; 62; 63]. A final point for further consideration when discussing ionospheric storm effects, is that it is not yet fully clarified whether foF2/NmF2 and TEC storm time responses always share the same features, and therefore, results obtained from the analysis of data from different data sources should be considered cautiously. TEC is defined as the integral of the entire ionospheric electron density profile. Such an integral has its maximum contribution from the F2 layer, with approximately 2/3 of the TEC coming from regions above the altitude (hmF2) of peak density (NmF2) [64]. Therefore, if substantial effects occur in TEC, simple vertical redistributions of F layer plasma cannot be the main cause [22]. In addition, in case the electron concentration at heights of the layer maximum is more sensitive to changes in thermospheric processes, and the effects of electrodynamics influence strongly higher altitudes which contribute substantially to the TEC estimates, one may expect quantitatively and maybe qualitatively different responses between foF2/NmF2 and TEC. Indeed, such discrepancies have been reported in the literature, such as, for instance, the results from the analysis of [PERSON] et al. [65]. The authors conducted an epoch analysis of global ionosphere responses to recurrent geomagnetic activity during 79 corotating interaction region (CIR) events from 2004 to 2009 using GPS-derived TEC values, to find that in the high and middle latitudes, the TEC data showed a positive effect on the first storm day, while the negative response in the following days was only evident in the high latitudes.