The Dungey cycle is considered from the formation of a magnetic barrier and
necessary for dayside reconnection conditions till the electric field generation
around the Birkeland current loop and magnetic flux circulation balance. Data based modeling of the magnetosheath magnetic field makes it possible to
quantitatively assess the main factors that control formation and destruction
of the magnetospheric magnetic barrier, such as the field line draping and
the field intensity increase from the bow shock to the magnetopause, as well
as their dependence on the orientation of the interplanetary magnetic field
(IMF). The Dungey cycle has been revised to take into account the essentially
time-dependent effects of magnetic reconnection. It is shown by means of
the Stokes’ theorem that a powerful electric field with an effective potential
difference of several tens of kV is generated around the developing substorm
current system. The emerging Birkeland current loop is an important particle
acceleration element in the magnetosphere, contributing to the energization
of ring current protons and electrons. The electric field that arises in the
dipolarization zone magnifies the already existing ring current, and the closure
of its amplified part through the ionosphere generates the Region 2 fieldaligned
currents. The motion of the expanding partial ring current around the magnetosphere, combined with the particle drift, transfers the magnetic flux from the night side of the magnetosphere to the dayside. At the dayside magnetopause, the reconnection is also responsible for the creation of the
Birkeland loop, but now the electric field in the loop area decelerates the ring
current particles, and regions of weakened ring current are formed. Closure of
these weakened loop currents results in a transfer of the magnetic flux from the
dayside to the night side, thus ensuring its overall balance and completing the
Dungey cycle.