Landmark values of the equatorial electrojet: the minimum intensity Jm A.km-1, its distance xm km and ratio to maximum intensity Jm/Jo; the magnetic field constant K nT; the maximum northward magnetic field Xo nT, and the distance of zero northward magnetic field wx km; the minimum northward magnetic field Xm nT, its distance um km and ratio to maximum northward field Xm/Xo; the vertical magnetic field Zo nT at the dip equator and the distance of zero vertical field wz km; the maximum vertical magnetic field ZM nT, its distance uM km and ratio to maximum northward field Zm/Xo; have all been derived from September equinox satellite data and they compare favourably with their values from ground-based data. Our Jm/Jo agrees excellently with MUSMANN and SEILER (1978) and ANANDARAO and RAGHAVARAO (1979); while our xm agrees excellently with the location of CAHILL's (1959) westward current, and the findings of MUSMANN and SEILER (1978). The landmark distances xm, wx, um, uM, wz and the ratios Jm/Jo, Xm/Xo and ZM/ Xo do not vary with longitude but the intensity Jm and magnetic fields, K, Xo, Xm, Zo and

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From the correlations of seven landmark distances, s, of the equatorial electrojet with its peak eastward current intensity Jo and its space gradient dJo/ ds, we find that the entire electrojet current system, with its magnetic field, tends to contract; consequently, the current and magnetic field foci, as well as contours of equal current intensity or of equal magnetic field, move towards the magnetic dip equator as the electrojet intensity increases. Furthermore, for a given increase in intensity, the greater the landmark distance the greater its contraction; and for movement of unit distance, the nearer the position to the dip equator the greater the increase in intensity required. Three causes which possibly contribute to the contraction are briefly discussed.

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