The Relation Between Ionospheric Poynting Flux Enhancement and Cusp Reconnection

During northward IMF periods the magnetosphere is usually quiet and little, if any, significant Poynting flux into the high latitude ionosphere is expected. However, DMSP frequently observes unusually high level of local Poynting flux at high latitude in the dayside when the IMF is northward, but also has a large By component. We use the OpenGGCM coupled magnetosphere-ionosphere-thermosphere code to study several events where under such conditions unusually large Poynting flux has been observed. We find that these events are well reproduced by the model. Analysis of the model results reveals that the Poynting flux hot spots are intricately linked with magnetic reconnection at the high-latitude cusps.