Planetary magnetic signature of the storm wind disturbance dynamo currents: Ddyn

During magnetic storms, Joule heating and ion drag, in auroral zones, strongly influence the circulation of thermospheric neutral winds. Joule heating produces equatorward neutral winds at F ‐region heights with return flow at E ‐region altitudes around the equator, the so‐called Hadley cell. The modified thermospheric circulation produces upwelling of molecule‐enriched air at high latitudes and global changes in the atmospheric composition. The equatorward neutral winds extending from the auroral zone to mid and low latitudes through the Coriolis force create westward storm wind which drives an equatorward dynamo current. In this paper, we detect for the first time, in the three longitude sectors, the planetary magnetic signature ( D dyn ) of ionospheric disturbance dynamo with its main features: (1) the decrease of the equatorial electrojet due to a westward electric current flow opposite to the regular eastward current flow and (2) the equatorward ionospheric disturbance dynamo currents at midlatitudes.