The ionospheric response to the Saint Patrick storm over South East Asia

ERICA, a project funded by the European Space Agency, aims at characterizing the ionospheric variability of the Equatorial Ionospheric Anomaly in the South East Asia. In particular, ERICA focuses on the variation of the plasma electron density in the southern and northern crests of the anomaly and over the dip equator identified by the Equatorial Ionospheric Trough. To achieve this goal, an ad hoc measurements campaign is on-going with ground-based instruments located in the footprints of the Equatorial Ionospheric Anomaly and of the Equatorial Ionospheric Trough in Vietnam and Indonesia. The campaign started on the 1st of March 2015, timing to monitor the Saint Patrick storm effects on the ionosphere by means of ionosondes, double frequency hardware and software defined radio GNSS receivers, ground based and spaceborne magnetometers and Langmuir probe. Such multi-instrumental and multi-parametric observations of the region enables an in-depth investigation of the ionospheric response to the largest geomagnetic storm of the current solar cycle. The observations record positive and negative ionospheric storms, sporadic E layer and spread F conditions, scintillations enhancement and inhibition, TEC gradients. The ancillary information on the local magnetic field allows to highlight the variety of ionospheric perturbations happened during the main and the long recovery phase of the storm. The paper presents the outcomes of the investigation evidencing the peculiarities of a region not yet extensively reported in the open literature.