Morphology Ionospheric dynamo region

figure 1. streamlines of equivalent ionospheric sq current during equinox (1957 - 1969) @ 12 ut separated primary (a) , secondary (b) part. between 2 streamlines flow 20 ka >

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figure 1a shows current streamlines of equivalent sq current seen sun @ noon. current configuration fixed sun, while earth rotates beneath it. total current of 140 ka flows within 1 daytime vortex. rotating sq current , electrically conducting earth interior behave huge transformer dynamo region primary winding , earth secondary winding. since sq current varies basic period of 1 day, electric currents induced within earth s interior. magnetic field of secondary current superimposed on magnetic field of primary sq current. methods separate both components go gauss. amplitude of secondary current 1/3 of of primary current , shifted in phase. figure 1b shows secondary component. ratio between sheet current , magnetic component given above has value one.

the sq current depends on season. summer vortex intensified compared winter vortex , reaches winter hemisphere. longitudinal dependence of sq current exists related inclined dipole component of internal magnetic field, nonmigrating tidal waves below. in course of 11-year solar cycle, amplitude of sq increases factor of more 2 sunspot minimum sunspot maximum. 2 thirds of increase may result enhancement of electric conductivity solar activity. rest due increase of wind speed caused temperature increase increasing solar activity. during night, electron density of ionospheric e-layer diminishes more of f-layer. therefore, height center of dynamo region shifts upward.

the main driver of sq current external (1, -2) tidal wave mode. due constant phase altitude, efficient drive coherent winds @ dynamo layer height, while currents generated internal modes interfere destructively @ various heights. fourier analysis shows semidiurnal component amplitude of 1 /2 of of diurnal component, phase shifted 180°. appears result of nonlinear coupling between product of diurnally varying wind , diurnally varying conductivity . centers of daytime vortices show day day variability. can attributed internal tidal modes sensitive varying meteorological conditions in lower , in middle atmosphere, in part solar activity.

near dip equator (where geomagnetic field lines horizontal), strong band of eastward flowing currents can observed in range of 150 km equator . such enhancement of sq current factor of 4 due cowling conductivity. during solar flare, bursts of solar radiation environment of active sunspot reach higher atmosphere, @ e- , d- layer heights, lasting @ 1 hour. electric conductivity increases, , sq current enhances on daytime hemisphere. small increase occurs, called geomagnetic solar flare effect or crochet. during solar eclipse, electric conductivity decreases in shadow region, , sq current , sq variation diminishes few nt in area. called geomagnetic solar eclipse effect. both events can observed during quiet geomagnetic activity.

in aftermath of strong magnetospheric disturbances, current system develops quasi

anti-sq-current. generated joule heating in polar thermosphere. current system called ddyn.