Speaker
Description
Geomagnetic storms are phenomena that pose a hazard to electronic devices on the earth’s surface. Accurate knowledge of the disturbance conditions of the Earth’s magnetic field is crucial to mitigate potential adverse effects. Here we present a comparison of the Dst and SYM-H global geomagnetic indices with local disturbance data from six stations in southern Europe over the period 1981-2021. It is known that the longitudinal distribution of the stations used in the derivation of both indices and their normalization process can lead to some loss of information or/and deviations from the local data, so we wanted to study if these indices were good representations of the magnetic disturbance in these latitudes. It was found that, on average, both indices were positively deviating from the local data below +10nT for the whole period, with the deviation in calm being below +6nT but increasing up to ∼+30nT for medium intensity storms and up to ∼+50nT for the most intense storms, with this last value varying up to ∼+80nT for the highest latitude station. In this analysis, a positive deviation implies an overestimation of the disturbance by the index with respect to the local data. Overall, SYM-H provided a better quantification of the disturbance during moderate to intense storms than Dst. However, negative peaks in deviation were recorded much larger in magnitude in the 1-minute data (SYM-H) than in the 1-hour data (Dst), implying rapid variations in the local data not recorded by the global indices. Thus, not only Dst and SYM-H are positively deviated with respect to the local disturbance, they also fail to record rapid negative drop peaks. This indicates that the quantification of the severity of magnetic storms requires a more comprehensive analysis than the description given by the geomagnetic indices.
| Do you plan to attend in-person or online? | In-person |
|---|
