Contributions from oceanic and ionospheric dynamos to the lunar daily variation at Alibag

The contributions from the oceanic and ionospheric dynamos, Lo and LI respectively, to the geomagnetic lunar daily variation, L, at Alibag, a coastal station in the Indian equatorial region, are calculated from the L harmonics derived from a 41-yr long series of observations. The analysis in the calendar months shows a steady and significant ocean dynamo contribution in the vertical component, Z, in all the months except April. Examination, by an analysis of the data year by year, of the association of Lo and LI with varying solar and magnetic activities reveals, surprisingly, a stable correlation between the magnetic activity index AP and the oceanic part in the horizontal and vertical components but not in declination, which probably indicates the influence of induced currents, along the latitudes, on Lo