The relation between dayside local Poynting flux enhancement and cusp reconnection

We use the Open Geospace General Circulation Model (OpenGGCM) coupled magnetosphere-ionosphere-thermosphere code to study several events where, under such conditions, unusually large earthward Poynting flux has been observed.

We find that the Joule heating rate in the model agrees well with the observed Poynting flux. Analysis of the model results shows that the strong Poynting flux hot spots are physically linked with magnetic reconnection at the high-latitude cusps. The solar wind mechanical force and the J × B force act on the newly opened field lines created by cusp reconnection to produce a Pedersen current, which consequently generates an intense Joule heating region, and a pair of adjacent and opposite field-aligned currents (FACs) connecting to the magnetopause currents forming a closed circuit.