FIELD-ALIGNED CURRENTS OBTAINED FROM THE INTERKOSMOS- BULGARIA-1300 SATELLITE DATA.

Single satellite observations allow the correct calculation of the value of field-aligned currents (FAC) only when the scale of field-aligned current band in the latitudinal direction is much smaller then such scale in the longitudinal direction. The analysis shows that the change of the measured on satellite tangential component of the magnetic field in the case of finite current sheet is less than such change when the sheet is infinite (with same current density). This effect leads to underestimation of the value of field-aligned currents. The appeared systematic error of the calculation of field-aligned currents is evaluated. The magnetic field measurements aboard satellite Intercosmos-Bulgaria-1300 in the period August - December 1981 are used. The statistical pictures of the distribution of density and scales of field-aligned current bands are obtained.