A quantitative model is developed for computing currents and electric fields in the area covered by the poleward set of field-aligned currents (region 1 Birkeland currents). The high-latitude band considered carries most of the westward electrojet and lies just poleward of the region treated in the Rice University computer simulation (which covers the inner magnetosphere and corresponding ionosphere); the present high-latitude-current model supplements the inner-magnetosphere simulations to make them nearly global. Birkeland current and aurorally enchanced conductivity are assumed to be uniformly distributed across the band. The area poleward of the band is taken to be an insulator, while boundary conditions at the low-latitude edge of the band are derived from the results of the lower-latitude computer simulations of the substorm event that occurred on September 19, 1976. The time-dependent conductivity model used is based on electron fluxes and mean energies measured from the Air Force S3-2 satellite. Ionospheric electric fields and currents are calculated; ionosphere neutral winds are neglected. Model predictions of the locations of the electric-field reversal agree well with typical OGO 6 satellite observations. The model also agrees with S3--2 data from September 19, 1976, on an important feature, namely, the electric field reversal usually occurs poleward of the bulk of region 1 current. Joule heating of the upper atmosphere, as inferred from calculation of currents and electric fields in the high-latitude region considered here, was found to be about 2¿1011 W during the substorm period, somewhat less than the value estimated for the lower-latitude region (region 2 and below). Model values for the strength of the electrojet and the amount of Joule heating agree to within ~20% with resutls based on a simple Cowling conductivity band (with no latitudinal current flowing into the band).