A STUDY OF ELECTRIC FIELDS IN THE HIGH-LATITUTE IONOSPHERE BY USING AURORAL RADAR SYSTEM STARE——PHYSICAL DISCUSSIONS

Some features of STARE observed convection pattern both at relatively quiet days (1≤K_p≤3) and disturbed days (∑K_p>27) are discussed with simple model method.The electric field variations at quiet days are found to be reasonably in agreement with one of Vasyliunas' models.The observed deviation from the dawn-dusk symmetric pattern can be partly explained by the day-to-night gradient of the ionospheric conductivity.It also implies the existence of asymmetric factors within the magnetosphere.Two simple models are suggested to interpret the westward rotation of the convection pattern during disturbed days.The feature is referred to the effect of the relative intensity of the two field-aligned current regions in one of the models and attributed to the modulation of the ratio between the Hall and Pederson conductivities in another.The comparison between the two is made and it is shown that in order to make clear that which factor is more important the futher understanding of the magnetosphere and the simultaneous observations of E-field,field-aligned current are both necessary.