TID Observations and Source Analysis During the 2017 Memorial Day Weekend Geomagnetic Storm Over North America

Abstract

We investigate ionospheric perturbations associated with traveling ionospheric disturbance (TID) during the geomagnetic storm on Memorial Day weekend (28 May) 2017. Results show the presence of both equatorward propagating large-scale TIDs (LSTIDs) and poleward propagating medium-scale TIDs. Equatorward moving TIDs are connected with enhanced auroral activity owing to geomagnetic storm conditions, while poleward TIDs are believed to be induced by local atmospheric gravity wave sources originating from convection activities near the West Coast of North America. Measurements from magnetometers located in the west, central, and east regions of North America are used to evaluate energy inputs from the auroral belt, and these observations confirm that equatorward LSTIDs are due to geomagnetic disturbance. The observed LSTID waves were characterized by some uncommon features, such as horizontal wavefront stretching from coast to coast, aligned in the NW to SE direction, and propagating to the southwest (equatorward) direction during the storm main phase period. In contrast, during the recovery phase and on other experimental control days, the observed medium-scale TIDs were characterized with relatively smaller wavelengths aligned in the NW to SE direction and propagate primarily in the northeast (poleward) direction. Our results also reveal that LSTID waves appear to travel faster in the central continental region compared to LSTIDs in the western and eastern regions.