Publication Date:
2017-12-22
Description:
Ionospheric storm effects at midlatitudes were analyzed using different ground-based
instruments distributed in Italy during the 13–15 November 2012 geomagnetic storm. These included an
all-sky imager (ASI) in Asiago (45.8°N, 11.5°E), a network of dual-frequeny Global Navigation Satellite Systems
receivers (Rete Integrata Nazionale GPS network), and ionosondes in Rome (41.8°N, 12.5°E) and San Vito
(40.6°N, 17.8°E). GPS measurements showed an unusual enhancement of total electron content (TEC) in
southern Italy, during the nights of 14 and 15 November. The ASI observed colocated enhancements of
630 nm airglow at the same time, as did variations in NmF2 measured by the ionosondes. Moreover, wave-like
perturbations were identified propagating from the north. The Ensemble Empirical Mode Decomposition,
applied to TEC values revealed the presence of traveling ionospheric disturbances (TIDs) propagating
southward between 01:30 UT and 03:00 UT on 15 November. These TIDs were characterized by weak TEC
oscillations (~ ±0.5 TEC unit), period of 45 min, and velocity of 500 m/s typical of large-scale TIDs. Optical
images showed enhanced airglow entering the field of view of the ASI from the N-NE at 02:00 UT and
propagating to the S-SW, reaching the region covered by the GPS stations after 03:00 UT, when TEC
fluctuations are very small (~ ±0.2 TEC unit). The enhancement of TEC and airglow observed in southern Italy
could be a consequence of a poleward expansion of the northern crest of the equatorial ionization anomaly.
The enhanced airglow propagating from the north and the TEC waves resulted from energy injected at
auroral latitudes as confirmed by magnetometer observations in Scandinavia.
Description:
Published
Description:
11794–11806
Description:
2A. Fisica dell'alta atmosfera
Description:
1IT. Reti di monitoraggio
Description:
5IT. Osservatori
Description:
JCR Journal
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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