Nonlinear connection between the auroral (Au, Al) and mid-latitude (SYM-H, ASY-H)) geomagnetic activity indices at the main phase of geomagnetic storm

Nonlinear connection between the magnetic disturbances in the auroral region and those at middle and low latitudes at the main phase of a geomagnetic storm has been analyzed. The method of artificial neural network was applied. The level of geomagnetic storminess in auroral region was estimated from indices of auroral electrojet intensities (AU, AL). At middle latitudes, it was estimated from indices of ring current intensities (SYM-H, ASY-H). The results showed the connection between the symmetric part of ring current and the eastward and westward electrojets, but it was more apparent for the eastward electrojet. Asymmetric ring current showed nonlinear interaction with the westward electrojet only. The eastward electrojet was found to develop before the westward one during geomagnetic storms. The characteristic times of advancing in development of mid-latitude magnetospheric processes relative to auroral ones were determined. These conclusions confirm the hypothesis of integrated ionosphere-magnetospheric current system including asymmetric ring current, eastward and westward electrojets. Nonlinear interaction between the symmetric part of ring current and the auroral electrojets is caused by the activation of these current systems by the same source. The possibility of satisfactory neural network restoration of indices of auroral electrojet intensity from the ring current indices is shown. The neural network classification of events under study determines the relationship of geomagnetic disturbance dynamics and duration with efficiency of neural network restoration of this event.