Geomagnetic Activity at Lampedusa Island: Characterization and Comparison with the Other Italian Observatories, Also in Response to Space Weather Events

Abstract

Regular automatic recordings of the time series of the magnetic field, together with routine manual absolute measurements for establishing dynamic baselines at Lampedusa Island—south of Sicily—Italy (geographic coordinates 35°31′N; 12°32′E, altitude 33 m a.s.l.), show a signature of very low electromagnetic noise. The observatory (provisional IAGA code: LMP) lays inside a restricted and remote wildlife reserve, far away from the built-up and active areas of the island, which at present is the southernmost location of the European territory for such observations. The availability of high-quality data from such site, whose survey started in 2005, is valuable for filling the spatial gap due to the lack of observatories in the whole south Mediterranean and North African sectors. We compare observations at Lampedusa, in both time and frequency domains, with those at the other Italian observatories (Castello Tesino and Duronia-L’Aquila), operating since the 1960s of last century, allowing us to report even the secular variation. Using data recorded in the last few years, we investigate higher frequency variations (from diurnal to Pc3-4 pulsations) in order to magnetically characterize the Italian territory and the local response to external forcing. In particular, we present a characterization in terms of diurnal variation and its seasonal dependence for the three observatories. This latter feature is in good agreement with a geomagnetic Sq-model, leading us to speculate about the position of the north Sq-current system vortex and its seasonal displacement with respect to the geographic positions of the observatories. We also study the geomagnetic individual response to intense space weather events by performing Superposed Epoch Analysis (SEA), with an ad-hoc significance test. Magnetic responses in the Ultra Low Frequency range (ULF) from spectral, local Signal-to-Noise Ratio (SNR) analyses under different local time, and polarization rates are computed. These latter studies lead us to search for possible signatures of magnetic field line resonances during intense space weather events, using cross-phase multi-observatory analysis, revealing the promising detection capability of such technique even at low latitudes. The geomagnetic observatories prove to be important points of observation for space weather events occurring at different spatial and time scales, originating in both upstream and ionospheric regions, here analyzed by several well-established methodologies and techniques. The quiet environmental site of LMP, providing high-quality geomagnetic data, allows us such investigations even at inner Earth’s magnetospheric shell.

Evaluating the Effect of Noise from Traffic on HYB Magnetic Observatory Data during COVID-19 Lockdown

“…Ref. [13] identified the noise in the Duronia (DUR) Observatory data during 2018 by computing the signal-to-noise ratio (SNR) on hourly averaged power spectra of both horizontal components (H and D). The observed noise peak at DUR during morning hours was ascribed to the contribution of Pc3-Pc4, as well the contribution of higher levels of local noise in the data.…”

Wavelet Model of Geomagnetic Field Variations and Its Application to Detect Short-Period Geomagnetic Anomalies

“…The collected sets of geomagnetic data allow one to investigate space-time features, study the dynamics of the processes in the Earth magnetosphere, and look for nonstationary manifestations of space weather. Thus, they are valuable satellite data support [2][3][4][5][6]. Investigation of geomagnetic data is of interest in different spheres of human activities, for example, research of atmosphere and hydrosphere [7], the study of the Earth deep structure (magnetotelluric sounding) [8,9], space weather forecast [2][3][4][5][6]10,11], seismic activity monitoring [12], and so on.…”

“…Thus, they are valuable satellite data support [2][3][4][5][6]. Investigation of geomagnetic data is of interest in different spheres of human activities, for example, research of atmosphere and hydrosphere [7], the study of the Earth deep structure (magnetotelluric sounding) [8,9], space weather forecast [2][3][4][5][6]10,11], seismic activity monitoring [12], and so on. The negative impact of geomagnetic disturbances on technical objects and on human health [13][14][15][16][17][18][19] determines the important applied significance of the research.…”

“…They occur in the polar region and propagate to the region of mid-and low-latitudes as geomagnetic activity grows. Thus, the task of the current diagnostics of such events is quite topical and is has been solved for several decades by different scientists and research groups [2][3][4][5][6]12,[20][21][22][23][24].…”

“…Traditional methods for time series modeling (smoothing, spectral methods etc.) allow us to investigate long-term variations and regular diurnal changes of the magnetic field [2]. However, they are not effective enough to analyze sudden short-period features occurring during increased solar activity and magnetic storms [5,22,[24][25][26].…”