Global disturbance currents in the ionosphere during storms

The thermospheric neutral wind and ionospheric layer conductance at latitudes higher than 45 degrees (provided from empirical models), as well as the conductivities caused by solar irradiation (deduced from model parameters: neutral temperature, concentration and electron density) are used to calculate the distribution of the electrostatic potential, current and electric field between geomagnetic latitude +/- 72 degrees and 0-24h MLT in terms of the ionospheric current continuity equation, on June- and December-solstices during strong storms. The driving electric field across the polar cap and the region 2 field-aligned current, caused by the magnetospheric coupling, are taken into account in the calculation. The results represent the complexities and varieties about the coupling between disturbances of the magnetosphere, the thermospheric wind and the distribution of ionospheric conductance. The penetration of disturbed currents from the auroral zone to midand low-latitude area is often asymmetrical between the southern and northern hemispheres. Both the intensification of the eastward equatorial electrojet on the day side at the beginning of a storm, and later, the appearance of the westward equatorjet after noon, can be found frequently during storm periods. In the moderate high latitude areas the existence of a eastward electric field in the midnight-dawn region is an expected mechanism, which can be used to explain phenomena found many times in our previous works, due to its E x B upper-ward drift effect. (c) 2005 Elsevier Ltd. All rights reserved.Geochemistry & GeophysicsMeteorology & Atmospheric SciencesSCI(E)EI1ARTICLE7793-8026