Auroral Disturbance Driving of Large-Scale Traveling Ionospheric disturbances (LSTIDs)

Abstract:

Forcing from the auroral oval has dramatic effects on the ionosphere and thermosphere. One means by which this forcing affects the ionosphere and thermosphere globally is via atmospheric gravity waves that result from auroral energy and momentum input. The waves are manifested in the ionospheric as large-scale traveling ionospheric disturbances (LSTIDs). The question then arises as to what specific characteristics of auroral forcing lead to LSTIDs. We have previously shown that meso-scale flow channels that lead to auroral streamers are a major source of LSTIDs, including those associated with substorms. Initial evidence suggests that the strength of ground magnetic perturbance is critical to determining whether or not a particular flow channels leads to a LSTID detectable with total electron content measurements. We will show evidence that other disturbances such as dawnside auroral polarization streams (DAPS) and solar wind shock impacts can lead to LSTIDs, detectability being also dependent on whether or not they lead to a substantial ground magnetic disturbance. The area covered by a disturbance, precipitating energy fluxes, and duration of a particular disturbance will also be considered.