Some features of the variability associated with solar and lunar daily variations

Long-term variability in solar and lunar daily variations, and its association with solar and magnetic activity, in the three geomagnetic elements, H, D and Z, at Alibag is studied by an analysis of the data for each year separately during the period 1932-72. From year to year, considerable change in amplitude, with very small change in phase, is noticed in the case of solar daily variation, whereas, for lunar daily variation, changes in both amplitude and phase are found to be large. Solar cycle influence on the solar daily variation is observed to be prominent, and a distinct influence on the lunar daily variations is also seen; the observed influence of magnetic activity on these variations appears to be merely a reflection of the strong association between solar and magnetic activities